Urinalysis Microscopic Techniques in Clinical Microscopy
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Questions and Answers

What is the main function of nephrons?

Removal of waste products and reabsorption of nutrients.

Where are cortical nephrons located?

  • In the medulla
  • In the cortex (correct)
  • Between medulla and cortex
  • None of the above

    • Proteins are allowed to pass through the glomerulus in healthy urine.

    False

    Urine should always be negative for _____ or protein.

    <p>albumin</p> Signup and view all the answers

    What is the formula for renal blood flow?

    <p>PAH Test measures the amount of blood flowing through the kidney.</p> Signup and view all the answers

    Low specific gravity in urine indicates dehydration. (True/False)

    <p>True</p> Signup and view all the answers

    Which substance is considered exogenous in the context of GFR testing?

    <p>Inulin</p> Signup and view all the answers

    Beta-2-Microglobulin dissociates from HLA at a constant rate and is rapidly removed by _____.

    <p>filtration</p> Signup and view all the answers

    Match the following substances with their characteristics:

    <p>PAH Test = Measures blood flow through the kidney Titratable Acidity = Detects inability to secrete hydrogen molecules Urinary Ammonia = Detects inability to produce ammonia Specific Gravity Testing = Determines kidney's ability to concentrate urine</p> Signup and view all the answers

    What pigments are responsible for the yellow color of normal urine?

    <p>urochrome, urobilin, and uroerythrin</p> Signup and view all the answers

    What is the primary test for routine urinalysis?

    <p>reagent strip test</p> Signup and view all the answers

    What is the primary principle of the refractometer in determining specific gravity?

    <p>Velocity and angle of light passing through a solution</p> Signup and view all the answers

    Bilirubin that produces foam when shaken indicates normal liver function.

    <p>False</p> Signup and view all the answers

    Orange urine may be due to the presence of ________.

    <p>pyridium</p> Signup and view all the answers

    What is the purpose of collecting a 24-hour (timed) urine specimen?

    <p>To provide quantitative results</p> Signup and view all the answers

    Suprapubic aspiration can be used to diagnose prostatic infection.

    <p>True</p> Signup and view all the answers

    What does a urine bag 'Wee Bag' collect samples from?

    <p>infants</p> Signup and view all the answers

    If a urine specimen is catheterized, it is collected from a catheter passed into the _________.

    <p>bladder</p> Signup and view all the answers

    Match the following common urine specimens with their descriptions:

    <p>Random = Can be collected anytime without specific instruction Clean-Catch = Requires cleansing of the genital area before sample collection Catheterized = Collected through a catheter passed into the bladder 24Hour (Timed) = Used to measure hcg titer</p> Signup and view all the answers

    What is the threshold for glucose in the proximal convoluted tubule (PCT) which may result in the presence of glucose in urine in cases of DM?

    <p>160-180 mg/dL</p> Signup and view all the answers

    What is the main function of the ascending loop of Henle?

    <p>Reabsorption of salt</p> Signup and view all the answers

    Glomerular filtration is selective and only allows substances with a molecular weight less than 70,000 kD to pass through.

    <p>False</p> Signup and view all the answers

    The gold standard test for assessing glomerular filtration rate (GFR) is the __________ clearance test.

    <p>inulin</p> Signup and view all the answers

    What is the main role of tubular secretion in the kidneys?

    <p>Eliminating substances that were not filtered by the glomerulus</p> Signup and view all the answers

    What causes the decrease in glucose in urine?

    <p>glycolysis and bacteria utilizing glucose as an energy source</p> Signup and view all the answers

    Why does the clarity of urine decrease?

    <p>due to the formation of crystals and increase in bacteria cells resulting in a hazy result</p> Signup and view all the answers

    Bilirubin is oxidized to urobilinogen in urine. True or False?

    <p>False</p> Signup and view all the answers

    What is responsible for the increase in pH and change in odor in urine?

    <p>Ammonia</p> Signup and view all the answers

    Increased bacteria in urine leads to an ______ in pH, nitrite, and specific gravity.

    <p>increase</p> Signup and view all the answers

    Which type of cast indicates glomerulonephritis?

    <p>RBC Casts</p> Signup and view all the answers

    What is the final degenerative form of casts called?

    <p>Waxy casts</p> Signup and view all the answers

    In patients suffering from pyelonephritis, what casts can be formed when white blood cells are enmeshed with the protein matrix?

    <p>Pus casts</p> Signup and view all the answers

    Tubular necrosis is often caused by bacterial infections.

    <p>False</p> Signup and view all the answers

    Isosthenuria is characterized by a specific gravity of ________.

    <p>1.010</p> Signup and view all the answers

    Which of the following staining solutions is used to differentiate pus cells from other cells in urinary sediment?

    <p>Sternheimer-Malbin</p> Signup and view all the answers

    What does the sodium nitroprusside test indicate when examining urine sediment?

    <p>Melanin</p> Signup and view all the answers

    Which microscopy technique is specifically used to aid in identifying motility of spirochetes like Treponema pallidum?

    <p>Dark-field Microscopy</p> Signup and view all the answers

    What is the primary function of Phase-Contrast Microscopy in clinical microscopy?

    <p>Visualization of elements with low refractive indices</p> Signup and view all the answers

    Where do casts form or develop in the nephrons?

    <p>Distal convoluted tubule and collecting ducts</p> Signup and view all the answers

    What are oval fat bodies?

    <p>Renal tubular epithelial cells that have absorbed lipids</p> Signup and view all the answers

    What are yeast cells characterized by?

    <p>Oval structures with buds or mycelia</p> Signup and view all the answers

    Which staining methods can confirm the presence of oval fat bodies?

    <p>All of the above</p> Signup and view all the answers

    Abnormal crystals in urine are found in alkaline conditions.

    <p>False</p> Signup and view all the answers

    Uric Acid Crystals have a __ appearance with many shapes and forms including flat-sided rhombic plates, wedges, and rosettes.

    <p>pleomorphic</p> Signup and view all the answers

    What is the main indication for testing for glucose in urine?

    <p>detection of unsuspected diabetes mellitus or follow-up of known diabetic patients</p> Signup and view all the answers

    What is microalbuminuria defined as?

    <p>Urinary excretion of 30 to 300 mg of albumin in 24 hours</p> Signup and view all the answers

    Microalbuminuria is considered as the earliest sign of renal damage in diabetes mellitus.

    <p>True</p> Signup and view all the answers

    Microalbuminuria precedes the development of diabetic nephropathy by a few ____.

    <p>years</p> Signup and view all the answers

    What is the purpose of the test described in the content as being more sensitive than Benedict’s qualitative test, and specific only for glucose?

    <p>To test for glucose in urine</p> Signup and view all the answers

    Which test is used to detect ketone bodies in urine and reacts with acetoacetic acid and acetone but not β-hydroxybutyric acid?

    <p>Rothera’s test</p> Signup and view all the answers

    True or False: Bilirubinuria indicates conjugated hyperbilirubinemia.

    <p>True</p> Signup and view all the answers

    The formation of _______________ from hemoglobin in the reticuloendothelial system leads to bilirubin circulate in blood.

    <p>bilirubin</p> Signup and view all the answers

    What is the purpose of Fouchet's test?

    <p>To test for the presence of bile salts by observing the behavior of sulfur particles in urine.</p> Signup and view all the answers

    Which salts combine with glycine or taurine to form complex salts or acids in the small intestine?

    <p>Bile salts</p> Signup and view all the answers

    Bile salts act as detergents to emulsify fat droplets by reducing the surface tension on fat droplets to aid in fat digestion by __________.

    <p>lipases</p> Signup and view all the answers

    Reduced intestinal bacterial flora can lead to an increase in the formation of urobilinogen in the gut.

    <p>True</p> Signup and view all the answers

    What is the term for the presence of free hemoglobin in urine?

    <p>hemoglobinuria</p> Signup and view all the answers

    Which of the following is a cause of hemoglobinuria?

    <p>Intravascular hemolysis</p> Signup and view all the answers

    Myoglobin is a protein present in smooth muscle.

    <p>False</p> Signup and view all the answers

    Myoglobinuria occurs due to injury to ________ muscle.

    <p>skeletal</p> Signup and view all the answers

    What is the term used to describe the presence of many white blood cells in urine?

    <p>Pyuria</p> Signup and view all the answers

    What is the characteristic feature of hyaline casts found in urine?

    <p>Homogenous, colorless, transparent, and refractile</p> Signup and view all the answers

    Casts in urine are primarily composed of red blood cells and white blood cells.

    <p>False</p> Signup and view all the answers

    What type of crystals are colorless, refractile, and envelope-shaped, sometimes dumbbell-shaped, and soluble in dilute hydrochloric acid?

    <p>Calcium oxalate crystals</p> Signup and view all the answers

    What crystals may be mistaken for cysteine crystals that also form in acid urine?

    <p>Calcium carbonate crystals</p> Signup and view all the answers

    Presence of renal tubular epithelial cells in urine is indicative of _____________.

    <p>significant finding</p> Signup and view all the answers

    Match the following urine elements with their descriptions:

    <p>White blood cells (pus cells) = Spherical cells, indicative of infections when present in large numbers Oval fat bodies = Degenerated renal tubular epithelial cells filled with lipid droplets Squamous epithelial cells = Large cells with rectangular shape typically indicating contamination with vaginal fluid Transitional epithelial cells = Cells lining renal pelvis, ureters, bladder, and upper urethra</p> Signup and view all the answers

    Tyrosine crystals are soluble in alkali.

    <p>True</p> Signup and view all the answers

    Leucine crystals are ___ in alkali.

    <p>soluble</p> Signup and view all the answers

    What is the main indication for testing for glucose in urine?

    <p>detection of unsuspected diabetes mellitus or follow-up of known diabetic patients</p> Signup and view all the answers

    Which parameter indicates glomerular disease when proteinuria exceeds a certain level?

    <p>Proteinuria &gt;3500 mg/24 hours</p> Signup and view all the answers

    Microalbuminuria is defined as urinary excretion of _____ mg/24 hours of albumin in urine.

    <p>30 to 300</p> Signup and view all the answers

    What is the purpose of Fouchet’s test?

    <p>To detect the presence of bile salts</p> Signup and view all the answers

    What is the composition of Fouchet’s reagent used in Fouchet's test?

    <p>All of the above</p> Signup and view all the answers

    Glucosuria occurs when the filtered glucose load exceeds the capacity of renal tubular reabsorption.

    <p>True</p> Signup and view all the answers

    True or False: The main function of bile salts is to emulsify fat in the small intestine.

    <p>True</p> Signup and view all the answers

    Bile salts combine with ________ or taurine to form complex salts or acids.

    <p>glycine</p> Signup and view all the answers

    What is the enzyme involved in the oxidation of chromogen in the reagent strip test for glucose in urine?

    <p>Peroxidase</p> Signup and view all the answers

    Which ketone bodies are detected by Rothera's nitroprusside method?

    <p>Acetoacetic acid</p> Signup and view all the answers

    The sensitivity of Rothera's test is 1-5 mg/dl of ________ and 10-25 mg/dl of acetone.

    <p>acetoacetate</p> Signup and view all the answers

    Bilirubin appears in urine before clinical jaundice in acute viral hepatitis. Is this statement true or false?

    <p>True</p> Signup and view all the answers

    Match the following tests for bilirubin detection with their descriptions:

    <p>Foam test = Shake urine in a test tube and observe for yellowish foam Gmelin's test = Mix concentrated nitric acid and urine to observe colors Lugol iodine test = Add Lugol iodine solution and observe for green color development Fouchet's test = Surface tension test for bile salts and conjugated bilirubin</p> Signup and view all the answers

    What is the presence of free hemoglobin in urine called?

    <p>hemoglobinuria</p> Signup and view all the answers

    Which of the following is a cause of Hemoglobinuria?

    <p>Intravascular hemolysis</p> Signup and view all the answers

    What protein is present in striated muscle and binds oxygen?

    <p>Myoglobin</p> Signup and view all the answers

    True/False: Myoglobinuria can be caused by injuries to skeletal or cardiac muscle.

    <p>True</p> Signup and view all the answers

    ______ test detects the esterase enzyme released in urine from granules of leucocytes.

    <p>Leucocyte esterase</p> Signup and view all the answers

    What is the significance of red cell casts in urine analysis?

    <p>They help to differentiate hematuria due to glomerular disease from hematuria due to other causes.</p> Signup and view all the answers

    Which crystals are colorless, refractile, flat rectangular plates with notched corners?

    <p>Cholesterol crystals</p> Signup and view all the answers

    Amorphous phosphates are seen in normal urinary sediment.

    <p>False</p> Signup and view all the answers

    Leucine crystals are soluble in _______.

    <p>alkali</p> Signup and view all the answers

    What is the term for spherical white blood cells found in urine?

    <p>pus cells</p> Signup and view all the answers

    Which term is used for the presence of many white cells in urine?

    <p>Pyuria</p> Signup and view all the answers

    Eosinophils are a characteristic feature of acute interstitial nephritis.

    <p>True</p> Signup and view all the answers

    ______ is a significant finding and indicates conditions causing tubular damage like acute tubular necrosis.

    <p>Renal tubular epithelial cells</p> Signup and view all the answers

    Match the urinary cast with its description:

    <p>Hyaline cast = Most common type of cast, colorless and transparent Waxy cast = Easily recognized, forms in prolonged stasis Granular cast = Cylindrical structures with degenerated cellular debris</p> Signup and view all the answers

    Study Notes

    Renal Physiology

    • Kidneys are the major organ of the excretory system, responsible for disposing waste products of metabolism and regulating plasma-water volume.
    • Each kidney has around 1-1.5 million nephrons, capable of urine formation, with cortical and juxtamedullary nephrons.
    • The main function of cortical nephrons is to remove waste products and reabsorb nutrients.
    • Juxtamedullary nephrons extend into the medulla and concentrate in the urine.

    Urine Formation

    • Urine formation involves three steps: glomerular filtration, tubular reabsorption, and tubular secretion.
    • Renal blood flow is approximately 1200 mL/min, with half of it being plasma.
    • Normal plasma flow is around 600-700 mL/min.
    • The glomerular tuft is the filtering apparatus, featuring eight (8) lobes of capillaries responsible for filtration.
    • Glomerular filtration is non-selective, allowing substances with a molecular weight less than 70,000 kD to pass through.

    Glomerular Filtration

    • Glomerular filtration rate (GFR) is approximately 120 mL/min.
    • The product of filtration is ultrafiltrate, with a specific gravity of 1.010.
    • Non-selective filtration of plasma substances with MWs less than 70,000 kD occurs.
    • Albumin is not allowed to pass through despite its MW being less than 70,000 kD due to its net electric charge and the membrane's electric charge.

    Tubular Reabsorption

    • Occurs mostly in the proximal tubule (PCT), transporting essential substances out of the tubular fluid back into the blood.
    • Reabsorption of glucose, amino acids, electrolytes, and water occurs in the PCT.
    • Substances reabsorbed in the PCT include 100% of glucose, 80-85% of nephrons, and essential nutrients.

    Renal Function Tests

    • Urinalysis is the first step/initial test to assess kidney function.
    • Glomerular filtration rate (GFR) can be measured using creatinine clearance test (usually 24 hours).
    • Sex-specific creatinine values differ between males and females.
    • Urea test is the first glomerular filtration test, but not commonly used due to its flaws.

    Urine Characteristics

    • Urine volume is around 180 L every 24 hours.
    • Urine composition is close to tissue fluid, with a specific gravity of 1.010.
    • Healthy urine is negative for protein and glucose.
    • Urine should always be negative for albumin or protein.### Renal Function Test
    • 65% of filtrate is reabsorbed in the renal tubules, including reabsorption of sodium and potassium
    • Urea is reabsorbed by the body, making it unreliable for determining GFR; creatinine is not reabsorbed and is a better marker
    • Inulin clearance test is the gold standard for GFR, but it is not practical for everyday use
    • Cystatin C is a marker for GFR that is produced by all nucleated cells at a constant rate

    Tubular Reabsorption and Secretion

    • Tubular reabsorption occurs in the ascending and descending loops of Henle and involves the reabsorption of sodium, potassium, and urea
    • Tubular secretion occurs in the peritubular capillaries and involves the removal of non-filtered waste products from the blood to the filtrate
    • Substances such as medication are bound to plasma carrier proteins and are too large to be filtered, but they can dissociate from the carrier proteins and be secreted into the filtrate
    • Small hydrogen molecules are easily filtered and must be returned to the blood, where they combine with phosphate ions or ammonia secreted by the renal tubular cells

    Regulation of Blood Pressure

    • Renin is secreted in response to low blood pressure, which activates angiotensinogen to angiotensin 1
    • Angiotensin 1 is converted to angiotensin 2 in the lungs, which causes vasodilation of afferent arterioles and constriction of efferent arterioles, increasing blood pressure
    • Aldosterone promotes reabsorption of salt, specifically sodium, making blood pressure high

    Urinalysis

    • Routine urinalysis includes physical examination, chemical examination, and microscopic examination
    • It is important for diagnosis of disease, monitoring progress of disease, and effectiveness of therapy
    • It can screen for asymptomatic patients and detect undetected disorders

    Types of Urine Specimens

    • Random: collected at any time of day without specific instruction

    • First Morning: collected immediately on arising

    • Clean-Catch: requires patient to cleanse the genital area, void first into the toilet, then collect specimen

    • Catheterized: collected via catheterization

    • 24-Hour (Timed): collects all urine during a designated period, often used to measure hCG titer

    • Drug Screening: requires strict chain-of-custody form requirements, and the sample must be safe and secured from collection to testing### Urine Collection Methods

    • Voiding into the toilet: a process where the patient is asked to clean their genitalia with soap and water, and then urinate into a toilet

    • 3-Glass Collection: a method used to diagnose prostatic infection and differentiate it from genitourinary tract infection

      • 1st vial: collects the first fraction of urine
      • 2nd vial: collects the midstream part of urine
      • 3rd vial: collects prostatic fluid with remaining urine volume (after digital prostate massage)

    • Catheterized: collected from a catheter passed into the bladder

    • SPA (Suprapubic Aspiration): direct puncturing of the bladder for urine collection

    • Pediatric Sample: collected using a urine bag (“Wee Bag”) or pediatric bag attached to the infant's genitalia

    Urine Preservation and Changes

    • Preservatives: used to prevent bacterial growth and preserve the specimen
      • Chemical preservatives: e.g., thymol, boric acid, formalin, and sodium fluoride
      • Refrigeration: preserves the specimen for 2 hours
    • Changes in Unpreserved Urine:
      • False increase: specific gravity, pH, urobilin, nitrite, bacteria, and odor
      • False decrease: glucose, clarity, urobilinogen, bilirubin, ketone bodies, and casts

    Physical Examination of Urine

    • Urine Volume:
      • Normal: 600-2000 mL/day
      • Oliguria: decreased output, less than 400 mL/day
      • Anuria: no urine output
    • Nocturia: increased urine output at night (exceeding 500mL/night)
    • Polyuria: increased urine output greater than 2.5L/day

    Abnormalities and Conditions

    • Diabetes Mellitus:
      • Polydipsia (excessive thirst)
      • Polyuria (excessive urination)
      • Polyphagia (excessive eating)
      • Low insulin/No insulin
      • Hyperglycemia
      • Glucosuria
    • Diabetes Insipidus:
      • Polydipsia
      • Polyuria
      • Low sp. Gravity (as low as 1.003)
      • Decreased/absent ADH
      • No hyperglycemia
      • No glucosuria

    Examination of Urine

    • Urinalysis is a commonly performed laboratory test in clinical practice.
    • Composition of normal urine is:
    • Volume: 600-2000 ml
    • Specific gravity: 1.003-1.030
    • Osmolality: 300-900 mOsm/kg
    • pH: 4.6-8.0

    Indications for Urinalysis

    • Suspected renal diseases (e.g. glomerulonephritis, nephrotic syndrome, pyelonephritis, renal failure)
    • Detection of urinary tract infection
    • Detection and management of metabolic disorders (e.g. diabetes mellitus)
    • Differential diagnosis of jaundice
    • Detection and management of plasma cell dyscrasias
    • Diagnosis of pregnancy

    Collection of Urine

    • Methods of collection: single specimen, random specimen, post-prandial specimen
    • First morning voided specimen is preferred for routine examination

    Proteinuria

    • Detection of microalbuminuria or early diabetic nephropathy
    • Grading of albuminuria:
      • Normal: <30 mg/24 hours
      • Microalbuminuria: 30-300 mg/24 hours
      • Macroalbuminuria: >300 mg/24 hours
    • Methods of quantitation:
      • Estimation of proteins in a 24-hour urine sample
      • Estimation of protein/creatinine ratio in a random urine sample

    Microalbuminuria

    • Significance:
      • Earliest sign of renal damage in diabetes mellitus (diabetic nephropathy)
      • Independent risk factor for cardiovascular disease in diabetes mellitus
    • Methods of detection:
      • Quantitative estimation of proteins in a 24-hour urine sample
      • Estimation of protein/creatinine ratio in a random urine sample
      • Test strips for microalbuminuria

    Bence Jones Proteinuria

    • Definition: urinary excretion of monoclonal immunoglobulin light chains (κ or λ)
    • Causes: plasma cell dyscrasias (e.g. multiple myeloma, primary amyloidosis)
    • Characteristics: thermal instability, precipitation at 40-60°C, re-dissolution at 85-100°C

    Glucosuria

    • Definition: excretion of glucose in urine
    • Causes:
      • Diabetes mellitus
      • Endocrine diseases (e.g. acromegaly, Cushing's syndrome, hyperthyroidism)
      • Non-endocrine diseases (e.g. central nervous system diseases, liver disorders)
      • Drugs (e.g. adrenocorticotrophic hormone, corticosteroids, thiazides)
      • Alimentary glycosuria (Lag-storage glycosuria)
    • Tests:
      • Benedict's qualitative test
      • Clinitest tablet method
      • Reagent strip method

    Ketones

    • Definition: breakdown products of fatty acids
    • Causes:
      • Decreased utilization of carbohydrates
      • Increased metabolic needs
      • Decreased availability of carbohydrates in the diet
    • Tests:
      • Rothera's test
      • Acetest tablet method
      • Ferric chloride test
      • Reagent strip test

    Bilirubin

    • Definition: yellow pigment produced during hemoglobin breakdown
    • Urine test for bilirubin:
      • Present in obstructive and hepatocellular jaundice
      • Absent in hemolytic jaundice
    • Table 1.6: Urine bilirubin and urobilinogen in jaundice### Bilirubin Tests
    • Bilirubin is a breakdown product of hemoglobin and is present in two forms: conjugated and unconjugated
    • Unconjugated bilirubin is bound to albumin, is not water-soluble, and cannot pass through glomeruli, therefore it does not appear in urine
    • Conjugated bilirubin is water-soluble, is filtered by glomeruli, and appears in urine
    • Detection of bilirubin in urine is helpful in the differential diagnosis of jaundice

    Ferric Chloride Test (Gerhardt's)

    • Addition of 10% ferric chloride solution to urine causes a reddish or purplish color if acetoacetic acid is present
    • The test is not specific and certain drugs can give a similar reaction
    • Sensitivity of the test is 25-50 mg/dl

    Reagent Strip Test

    • Modifications of nitroprusside test
    • Sensitivity is 5-10 mg/dl of acetoacetate
    • Reagent strips are vulnerable to improper storage and can give false-negative results

    Bilirubin Tests in Urine

    • Foam test: development of yellowish foam indicates presence of bilirubin
    • Gmelin's test: play of colors indicates positive test
    • Lugol iodine test: development of green color indicates positive test
    • Fouchet's test: development of blue-green color around the drop indicates presence of bilirubin

    Bile Salts

    • Salts of four different types of bile acids: cholic, deoxycholic, chenodeoxycholic, and lithocholic
    • Bile salts enter the small intestine through bile and act as detergents to emulsify fat and reduce surface tension
    • In the terminal ileum, bile salts are absorbed and enter the blood stream, then taken up by the liver and re-excreted in bile (enterohepatic circulation)

    Urobilinogen

    • Formed in the intestine through bacterial action on bilirubin
    • A portion of urobilinogen is absorbed in blood, undergoes recycling (enterohepatic circulation), and a small amount is excreted in urine
    • Normally about 0.5-4 mg of urobilinogen is excreted in urine in 24 hours
    • Urinary excretion of urobilinogen shows diurnal variation with highest levels in the afternoon

    Tests for Urobilinogen

    • Ehrlich's aldehyde test: reaction with urobilinogen produces a pink color
    • Reagent strip method: specific for urobilinogen
    • Watson-Schwartz test: used to distinguish between urobilinogen and porphobilinogen

    Hematuria

    • Presence of abnormal number of intact red blood cells in urine
    • Implies presence of a bleeding lesion in the urinary tract
    • Causes: diseases of urinary tract, hematological conditions, and hemoglobinuria

    Tests for Blood in Urine

    • Microscopic examination of urinary sediment
    • Chemical tests: benzidine test, orthotoluidine test, and reagent strip test
    • Reagent strip test: detects both intracellular and extracellular hemoglobin

    Hemosiderin

    • Presence of free hemoglobin in plasma

    • Appears as blue granules when urine sediment is stained with Prussian blue stain

    • Indicates intravascular hemolysis or hemoglobinuria### Screening Tests for Myoglobinuria

    • Myoglobin is soluble in 80% saturated solution of ammonium sulfate, while hemoglobin is insoluble and precipitates.

    • A positive chemical test for blood done on supernatant indicates myoglobinuria.

    Chemical Tests for Significant Bacteriuria

    • Leucocyte esterase test detects esterase enzyme released in urine from granules of leucocytes.
    • A positive test indicates pyuria, and urine culture should be done.

    Microscopic Examination of Urine

    • Microscopic examination of urine is also known as the "liquid biopsy of the urinary tract".
    • Urine consists of various microscopic, insoluble, solid elements in suspension.
    • These elements are classified as organized and unorganized substances.

    Urinary Sediments

    • Organized substances include red blood cells, white blood cells, epithelial cells, casts, bacteria, and parasites.
    • Unorganized substances are crystalline and amorphous materials.
    • Examination of urinary deposit is helpful in diagnosis of urinary tract diseases.

    Differentiation between Hematuria, Hemoglobinuria, and Myoglobinuria

    • Distinction between hematuria, hemoglobinuria, and myoglobinuria is based on urine color, plasma color, urine test, urine microscopy, serum haptoglobin, and serum creatine kinase.

    Microscopic Examination of Urine Sediment

    • Specimen: A mid-stream, freshly voided, first morning specimen is preferred.
    • Method: A well-mixed sample of urine is centrifuged, and the supernatant is poured off.
    • The tube is tapped at the bottom to resuspend the sediment, and a drop is placed on a glass slide and covered with a cover slip.

    Urinary Findings in Renal Diseases

    • Different conditions such as acute glomerulonephritis, nephrotic syndrome, and acute pyelonephritis have distinct urinary findings.

    Red Blood Cells

    • Normally, there are no or an occasional red blood cell in urine.
    • Red cells appear as small, smooth, yellowish, anucleate biconcave disks about 7 μ in diameter.
    • In glomerulonephritis, red cells are typically described as being dysmorphic.

    White Blood Cells (Pus Cells)

    • White blood cells are spherical, 10-15 μ in size, granular in appearance, with a visible nucleus.
    • Presence of many white cells in urine is called pyuria.
    • Clumps of pus cells or pus cells >10/HPF are suggestive of urinary tract infection.

    Casts

    • Urinary casts are cylindrical, cigar-shaped microscopic structures that form in distal renal tubules and collecting ducts.
    • Casts are composed of a precipitate of a protein that is secreted by tubules (Tamm-Horsfall protein).
    • Different types of casts include hyaline, granular, waxy, and fatty casts.
    • Presence of casts is indicative of disease of the renal parenchyma.

    Bacteria

    • Bacteria in urine can be detected by microscopic examination, reagent strip tests, and culture.
    • Significant bacteriuria exists when there are >105 bacterial colony forming units/ml of urine in a clean-catch midstream sample.

    Examination of Urine

    • Urinalysis is a commonly performed laboratory test in clinical practice.
    • Composition of normal urine is:
    • Volume: 600-2000 ml
    • Specific gravity: 1.003-1.030
    • Osmolality: 300-900 mOsm/kg
    • pH: 4.6-8.0

    Indications for Urinalysis

    • Suspected renal diseases (e.g. glomerulonephritis, nephrotic syndrome, pyelonephritis, renal failure)
    • Detection of urinary tract infection
    • Detection and management of metabolic disorders (e.g. diabetes mellitus)
    • Differential diagnosis of jaundice
    • Detection and management of plasma cell dyscrasias
    • Diagnosis of pregnancy

    Collection of Urine

    • Methods of collection: single specimen, random specimen, post-prandial specimen
    • First morning voided specimen is preferred for routine examination

    Proteinuria

    • Detection of microalbuminuria or early diabetic nephropathy
    • Grading of albuminuria:
      • Normal: <30 mg/24 hours
      • Microalbuminuria: 30-300 mg/24 hours
      • Macroalbuminuria: >300 mg/24 hours
    • Methods of quantitation:
      • Estimation of proteins in a 24-hour urine sample
      • Estimation of protein/creatinine ratio in a random urine sample

    Microalbuminuria

    • Significance:
      • Earliest sign of renal damage in diabetes mellitus (diabetic nephropathy)
      • Independent risk factor for cardiovascular disease in diabetes mellitus
    • Methods of detection:
      • Quantitative estimation of proteins in a 24-hour urine sample
      • Estimation of protein/creatinine ratio in a random urine sample
      • Test strips for microalbuminuria

    Bence Jones Proteinuria

    • Definition: urinary excretion of monoclonal immunoglobulin light chains (κ or λ)
    • Causes: plasma cell dyscrasias (e.g. multiple myeloma, primary amyloidosis)
    • Characteristics: thermal instability, precipitation at 40-60°C, re-dissolution at 85-100°C

    Glucosuria

    • Definition: excretion of glucose in urine
    • Causes:
      • Diabetes mellitus
      • Endocrine diseases (e.g. acromegaly, Cushing's syndrome, hyperthyroidism)
      • Non-endocrine diseases (e.g. central nervous system diseases, liver disorders)
      • Drugs (e.g. adrenocorticotrophic hormone, corticosteroids, thiazides)
      • Alimentary glycosuria (Lag-storage glycosuria)
    • Tests:
      • Benedict's qualitative test
      • Clinitest tablet method
      • Reagent strip method

    Ketones

    • Definition: breakdown products of fatty acids
    • Causes:
      • Decreased utilization of carbohydrates
      • Increased metabolic needs
      • Decreased availability of carbohydrates in the diet
    • Tests:
      • Rothera's test
      • Acetest tablet method
      • Ferric chloride test
      • Reagent strip test

    Bilirubin

    • Definition: yellow pigment produced during hemoglobin breakdown
    • Urine test for bilirubin:
      • Present in obstructive and hepatocellular jaundice
      • Absent in hemolytic jaundice
    • Table 1.6: Urine bilirubin and urobilinogen in jaundice### Bilirubin Tests
    • Bilirubin is a breakdown product of hemoglobin and is present in two forms: conjugated and unconjugated
    • Unconjugated bilirubin is bound to albumin, is not water-soluble, and cannot pass through glomeruli, therefore it does not appear in urine
    • Conjugated bilirubin is water-soluble, is filtered by glomeruli, and appears in urine
    • Detection of bilirubin in urine is helpful in the differential diagnosis of jaundice

    Ferric Chloride Test (Gerhardt's)

    • Addition of 10% ferric chloride solution to urine causes a reddish or purplish color if acetoacetic acid is present
    • The test is not specific and certain drugs can give a similar reaction
    • Sensitivity of the test is 25-50 mg/dl

    Reagent Strip Test

    • Modifications of nitroprusside test
    • Sensitivity is 5-10 mg/dl of acetoacetate
    • Reagent strips are vulnerable to improper storage and can give false-negative results

    Bilirubin Tests in Urine

    • Foam test: development of yellowish foam indicates presence of bilirubin
    • Gmelin's test: play of colors indicates positive test
    • Lugol iodine test: development of green color indicates positive test
    • Fouchet's test: development of blue-green color around the drop indicates presence of bilirubin

    Bile Salts

    • Salts of four different types of bile acids: cholic, deoxycholic, chenodeoxycholic, and lithocholic
    • Bile salts enter the small intestine through bile and act as detergents to emulsify fat and reduce surface tension
    • In the terminal ileum, bile salts are absorbed and enter the blood stream, then taken up by the liver and re-excreted in bile (enterohepatic circulation)

    Urobilinogen

    • Formed in the intestine through bacterial action on bilirubin
    • A portion of urobilinogen is absorbed in blood, undergoes recycling (enterohepatic circulation), and a small amount is excreted in urine
    • Normally about 0.5-4 mg of urobilinogen is excreted in urine in 24 hours
    • Urinary excretion of urobilinogen shows diurnal variation with highest levels in the afternoon

    Tests for Urobilinogen

    • Ehrlich's aldehyde test: reaction with urobilinogen produces a pink color
    • Reagent strip method: specific for urobilinogen
    • Watson-Schwartz test: used to distinguish between urobilinogen and porphobilinogen

    Hematuria

    • Presence of abnormal number of intact red blood cells in urine
    • Implies presence of a bleeding lesion in the urinary tract
    • Causes: diseases of urinary tract, hematological conditions, and hemoglobinuria

    Tests for Blood in Urine

    • Microscopic examination of urinary sediment
    • Chemical tests: benzidine test, orthotoluidine test, and reagent strip test
    • Reagent strip test: detects both intracellular and extracellular hemoglobin

    Hemosiderin

    • Presence of free hemoglobin in plasma

    • Appears as blue granules when urine sediment is stained with Prussian blue stain

    • Indicates intravascular hemolysis or hemoglobinuria### Screening Tests for Myoglobinuria

    • Myoglobin is soluble in 80% saturated solution of ammonium sulfate, while hemoglobin is insoluble and precipitates.

    • A positive chemical test for blood done on supernatant indicates myoglobinuria.

    Chemical Tests for Significant Bacteriuria

    • Leucocyte esterase test detects esterase enzyme released in urine from granules of leucocytes.
    • A positive test indicates pyuria, and urine culture should be done.

    Microscopic Examination of Urine

    • Microscopic examination of urine is also known as the "liquid biopsy of the urinary tract".
    • Urine consists of various microscopic, insoluble, solid elements in suspension.
    • These elements are classified as organized and unorganized substances.

    Urinary Sediments

    • Organized substances include red blood cells, white blood cells, epithelial cells, casts, bacteria, and parasites.
    • Unorganized substances are crystalline and amorphous materials.
    • Examination of urinary deposit is helpful in diagnosis of urinary tract diseases.

    Differentiation between Hematuria, Hemoglobinuria, and Myoglobinuria

    • Distinction between hematuria, hemoglobinuria, and myoglobinuria is based on urine color, plasma color, urine test, urine microscopy, serum haptoglobin, and serum creatine kinase.

    Microscopic Examination of Urine Sediment

    • Specimen: A mid-stream, freshly voided, first morning specimen is preferred.
    • Method: A well-mixed sample of urine is centrifuged, and the supernatant is poured off.
    • The tube is tapped at the bottom to resuspend the sediment, and a drop is placed on a glass slide and covered with a cover slip.

    Urinary Findings in Renal Diseases

    • Different conditions such as acute glomerulonephritis, nephrotic syndrome, and acute pyelonephritis have distinct urinary findings.

    Red Blood Cells

    • Normally, there are no or an occasional red blood cell in urine.
    • Red cells appear as small, smooth, yellowish, anucleate biconcave disks about 7 μ in diameter.
    • In glomerulonephritis, red cells are typically described as being dysmorphic.

    White Blood Cells (Pus Cells)

    • White blood cells are spherical, 10-15 μ in size, granular in appearance, with a visible nucleus.
    • Presence of many white cells in urine is called pyuria.
    • Clumps of pus cells or pus cells >10/HPF are suggestive of urinary tract infection.

    Casts

    • Urinary casts are cylindrical, cigar-shaped microscopic structures that form in distal renal tubules and collecting ducts.
    • Casts are composed of a precipitate of a protein that is secreted by tubules (Tamm-Horsfall protein).
    • Different types of casts include hyaline, granular, waxy, and fatty casts.
    • Presence of casts is indicative of disease of the renal parenchyma.

    Bacteria

    • Bacteria in urine can be detected by microscopic examination, reagent strip tests, and culture.
    • Significant bacteriuria exists when there are >105 bacterial colony forming units/ml of urine in a clean-catch midstream sample.

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    Description

    Test your knowledge of microscopic techniques used in urinalysis. This quiz covers the principles and methods of clinical microscopy in analyzing urine samples.

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