Lecture 2-Urine Analysis PDF

Examination of Urine Urinalysis Prof. Dr. Abdel-Raheim Meki Dr Ayat Sayed Dr. Eman Magdy Radwan Biochemistry Dept, Sphinx University  Urine is a liquid byproduct of the metabolism in humans. It is an ultrafiltrate of plasma. The kidneys are the organs responsi...

Examination of Urine Urinalysis Prof. Dr. Abdel-Raheim Meki Dr Ayat Sayed Dr. Eman Magdy Radwan Biochemistry Dept, Sphinx University  Urine is a liquid byproduct of the metabolism in humans. It is an ultrafiltrate of plasma. The kidneys are the organs responsible for excretion of urine. Kidneys filter a large volume of blood everyday, reabsorbing essential constituents such as water, sodium chloride, bicarbonate, phosphates, amino acids and glucose and secreting unwanted substances as those produced by metabolic pathways or substances introduced to the body through food or drugs.  Nephron Functional unit of the kidneys Urine is formed within the functional unit of the kidneys, nephron, which consists of glomeruli and tubules. Mechanisms of Urine Formation: 1. Glomerular Filtration: Formation of filtrate the glomerulus 2. Tubular Reabsorption: Substances (water, sodium chloride, bicarbonates, potassium, and calcium) pass from renal tubes of nephron to blood. 3. Tubular Secretion: Substances pass from blood to renal tubes of nephron (Secretion of waste products) ROUTINE URINALYSIS has two major components: A. Macroscopic analysis includes 1. Examining the urine for overall physical characteristics (Volume, Odour, Color, Aspect, pH, Specific gravity) 2. Examining the urine for chemical components (Nitrogenous constituents and Non-Nitrogenous constituents). (2) Microscopic analysis of urine involves examining the sample for formed elements. Clinical Significance of Urine Analysis The urine specimen is referred to as a liquid biopsy of the urinary tract. It yields great information about: 1. Diagnosis and management of renal or urinary tract disease. 2. Detection of metabolic or systemic diseases not directly related to the kidney.  I- Physical examination of urine 1- Volume: Normally: 800-2000 ml/day. Abnormally: (Polyuria, Oliguria and Anuria) 1. Polyuria: (more than 2000 ml/day) It is caused by: Physiological polyuria as in High fluid intake (water, tea) High protein diet (urea causes osmotic diuresis). Pathological polyuria as in Diabetes mellitus (glucose causes osmotic diuresis) Diabetes insipidus (due to lack of Antidiuretic hormone ADH) Hypertension (due to increased glomerular filtration) 2. Oliguria (less than 500 ml/day) Physiological oliguria as in low fluid intake and after excessive muscular exercises due to much sweating. Pathological oliguria as in Inflammatory kidney diseases (acute nephritis) Heart failure Severe oedema Fevers Vomiting and diarrhoea Obstruction in urine passages 3. Anuria (less than 125 ml/day) Acute tubular necrosis Bilateral renal stone 2- Specific gravity (SG) (urine relative mass density): Normally the relative mass density of urine collected over 24- hour ranges from 1015-1025. The higher SG, is the more the dissolved solids in urine e.g., urea, uric acid and glucose. The SG indicates the concentrating power of the kidney. It is one parameter of renal tubular function. Abnormally: SG is decreased in cases of diluted urine as in diabetes insipidus (urine volume↑ and SG ↓). and in chronic glomerulonephritis and renal failure where damage to kidney tubules affects their ability to reabsorb water. Increased in cases of concentrated urine as in: ✓ Diabetes mellitus (glucose-proteins-ketone bodies). ✓ Dehydration (urine volume↓ and SG↑) ✓ Nephrotic syndrome ✓ Heart failure 3- Odour: Fresh urine has an aromatic odour due to presence of volatile acids. On standing for any time, ammonia odour is due to decomposition of urea by bacteria Acetone odour is due to ketonuria Foul smell is due to infections of bacteria Some diet and medicine may change urine odour 4- Color: Normally: Pale or amber yellow. Dilute urine is very pale yellow while concentrated urine is deep orange The color of urine is due to 2 pigments, urochrome and urobilin Variation of urine color may result from many metabolic products, drugs and foods. Abnormally: Red or red brown color: Hematuria Brown color: Old blood or alkaptonuria Yellow-brown or green-brown: Jaundice 5- Urine pH Normally: Urine pH is acidic (about 5.5-6.5). Abnormally: Acidic urine (Low urine pH): Physiological causes: Severe exercise and protein rich diets. Pathological causes: Metabolic and respiratory acidosis, diabetic ketoacidosis and urinary tract infection UTI by E.coli. Alkaline urine (High urine pH): Physiological causes: Use of antacids and vegetarian diet (Ingestion of fruits (oranges, lemons), vegetables and legumes which contain salts of citric acids because they are metabolized into bicarbonates, and also they contain a high amount of alkaline minerals as potassium, calcium and magnesium. Pathological causes: Urinary tract infection caused by urea- splitting bacteria (Proteus and Pseudomonas split urea and produce ammonia) and Respiratory alkalosis 6- Aspect (appearance): Normally: Freshly voided urine is ordinarily clear and transparent. Abnormally: Turbid urine may be due to Pus (pyuria) Excess oxalic acid, calcium phosphate or urate crystals. Red cells (hematuria)  II- Chemical examination of urine Normal constituents of urine: Urine contains: (A) Organic constituents of urine: 1- Non-Protein Nitrogenous constituents (NPN): These include Urea, Uric acid, Ammonia, Creatinine, Creatine and Amino acids. 2- Non-nitrogenous organic constituents: These include carbohydrates (small undetected amounts ), lipids (small amount of short chain fatty acids) and organic acids as glucuronic acid, citric acid, lactic acid and oxalic acids in addition to vitamins ( water soluble vitamins ). (B) Inorganic constituents of urine: These include chlorides, phosphates, carbonates and sulfates. Examples on Normal Organic Nitrogenous constituents of urine: Urea: The main end product of protein metabolism. Normally, it ranges 20 - 40 gm/day. Uric acid: The end product of catabolism of purines in man either from diet or breakdown of tissue nucleoproteins. Ammonia: Normally, it is about 0.7 gm/day. Ammonia in urine is derived from deamination of amino acids mainly glutamine Glutaminase Glutamine  NH3 + Glutamic acid Creatinine: Its level in urine is about 1-1.8 gm/day in males and 0.7-1 gm/day in females. This difference is due to the muscle bulk of males. Creatinine: It is used in kidney function tests because it is: 1. Totally excreted in urine. 2. It is totally endogenously produced, and its level isn’t affected by type of food. Creatinine clearance test: Clinically, renal function can be assessed by measuring clearance rate of a creatinine from the blood to urine. Elevated blood creatinine levels - low creatinine clearance signifies impaired kidney function or kidney disease. U= Concentration of creatinine in urine in mol/L or mg/dL V= Volume of urine in ml per min P= Concentration of creatinine in serum in mol/L or mg/dL Examples on Normal Organic Non-Nitrogenous constituents of urine: Glucuronates: It is produced in liver. It combines with some toxic substances such as phenols and benzoic acid and detoxifies them (detoxification by conjugation). Oxalic acid (10 - 50 mg/day): It is a normal constituent of urine. It is mainly derived from the carbohydrate metabolism and from certain food. Citric acid (about 0.2 - 1.2 gm): It is also derived from the carbohydrate metabolism through Krebs' cycle. Lactic acid (about 50 - 200 mg): It is excreted daily. Its content in urine is increased in severe muscular exercises. Examples on Normal Organic Non-Nitrogenous constituents of urine: Chlorides: Its source is diet. The chloride content is diminished in fasting /starvation, in prostatic obstruction, nephritis, cardiac failure and in severe cases of vomiting, diarrhea, and burns. Sulphates: Its amount in urine depends mostly on protein diet. Its presence in urine is principally due to oxidation of sulphur amino acids (cystine, cysteine and methionine). Phosphates: Derived from the oxidation of phosphoproteins of diet (as casein of milk and vetillin of egg yolk), phospholipids and nucleoproteins. Urine pH generally depends on the ratio between acidic and basic phosphates. III- Microscopic examination of urine Deposits (sediments): Normally, urine contains no visible deposits. Abnormally: Upon centrifugation one or more of the following deposits may appear by using microscopical examination: Pus cells which are dead leucocytes (pyuria): It indicates UTI Red blood cells (hematuria): stones, tumors, or infections Epithelial cells Parasites and ova: e.g. belharzial ova. Crystals as urate, oxalate, phosphate crystals Casts: These are cylindrical structures formed basically from mucoprotein in the tubules. After formation, they become loose and go down the tubules into the urine.  Microscopic examination of urine Bilharzial ova RBCs  Abnormal constituents of urine: (Normally negative) 1. Proteins 2. Glucose 3. Bile pigments and bile salts 4. Blood 5. Ketone bodies 6. Indican 7. Pus 8. Stones 1. Protein: Normal urine protein (< 30 mg /L), includes (1) Albumin and globulin 30 % (2) Mucoprotein of renal origin called Tam Horsfall mucoprotein 70% Abnormal urine protein Microalbuminuria (30-200 mg/L)*: Indicates early affection of kidney as diabetes mellitus. Proteinuria (> 200 mg/L)**: In all acute and chronic kidney diseases. It may be albumin (albuminuria)which is the most common or globulin (globulinuria). Causes of Macro-albuminuria and Proteinuria Physiological causes: e.g., Severe muscular exercise, high protein diet and pregnancy. Pathological causes: Pre-renal: Hypertension, heart disease and liver disease. Renal: Nephrotic syndrome, glomerulonephritis and tumor of kidney. Post-renal: Inflammation of the lower urinary tract, bladder. Causes of Globulinuria (Bence Jones Proteins): Bence-Jones proteins are a part of antibodies called light chains. They are modified globulins of low M.W. These proteins are not normally in urine. It occurs in multiple myeloma. 2. Glucose: Glucosuria (glucose appear in urine) Normally level is 50-300mg/day not detectable. A normal renal threshold of glucose is about 180mg/dl of blood. It can be caused due to: Glucosuria with hyperglycaemia: Diabetes mellitus, hyperthyroidism, hyperpituitarism and Cushing’s syndrome Alimentary glucosuria after ingestion of carbohydrate rich diet Glycosuria without hyperglycaemia: e.g. renal glycosuria, nephrotoxic chemicals. Note: Presence of reducing sugar in urine is called glycosuria (Lactosuria, Galactosuria, Pentosuria) lactose appears in late stage of pregnancy and during lactation. 3. Bile pigments and Bile salts: Bile pigments appear in urine in amounts more than normal traces in hemolytic conditions, hepatic diseases and obstructive jaundice. Bile salts appear in urine more than normal traces in obstructive jaundice. 4. Blood and Blood pigments: Blood pigments may occur in urine as intact corpuscles (hematuria) or free hemoglobin in solution (hemoglobinuria). They are mainly present in bilharziasis, urinary tract stones and inflammation of kidney. Hematuria can be recognized by microscopic examination of the sediment obtained by centrifuging of the urine. 5. Ketone Bodies (acetone, acetoacetic acid and -hydroxyoutyric acid) Ketonuria may occur associated with impaired carbohydrate utilization. The excess ketone bodies in urine (ketonuria) is mainly associated with diabetes and it may provide the clue to early diagnosis of diabetic coma. Another condition associated with ketosis is starvation. 6. Indican: It arises from the bacterial putrefaction of tryptophan in the intestine and in abscess. Its excretion is a measure of the amount of putrefaction 7. Pus cells: Pus cells are dead WBCs and presence in urine is called pyuria. Pyuria indicates the presence of pathological conditions in the kidney. 8. Urinary stones (Calculi) Mainly classified into: Simple stone: consists of a single constituent Mixed stone: consists of more than one constituent Chemical composition: The most common substances enter in stone formation are Calcium oxalate, Calcium phosphate, Calcium carbonate and Magnesium ammonium phosphate Less commonly stones are formed of: Uric acid, cystine stone and xanthine stone.  Causes of urinary calculi: 1- Change in urine pH: as in UTI which makes the urine alkaline due to the action of bacteria on urea. Alkalinity causes PPTion of crystals and stone formation. 2- Disturbances in vitamins: Excess vitamin D: Leads to the absorption of excess calcium and causes calcium stone formation. Excess vitamin C: Ascorbic acid can be converted in human to oxalate which appears in urine. Massive overdose of vitamin C leads to the formation of calcium oxalate stones Def. of vitamin A: Leads to roughness of the lining epithelium of the urinary tract leading to precipitation of crystals and stone formation. 3-Disturbances in hormones: as in hyperparathyroidism and this leads to hypercalciuria and formation of calcium stones 4- Excess excretion of uric acid as in gout. This leads to formation of uric acid stones. 5- Excess excretion of cystine as in cystinuria. This leads to formation of cystine stones 6- Mucoproteins in urine: Mucoproteins act as the cement substance that binds the excreted salts to form stones Types of Urine Specimens: 1. Random (untimed) specimen. 2. Early morning urine (EMU): It is the most concentrated sample. It is the best sample type for routine urine analysis, and specific gravity assessment. 3. 24-hours sample: It is the sample of choice for quantitation of compounds in urine and for creatinine clearance tests. This sample should be collected through instructions for patient to start and end on empty bladder, collect urine in a clean container and the patient should be kept well hydrated during the day of collection. 4. Mid-stream urine: It is the sample used for culture and sensitivity test. It should be collected in a sterile container.  Urine sample must be collected in a clean, dry container, and should be examined within 30 minutes of voiding, and maximally within two hours of collection. Delay in analysis necessitates refrigeration or preservation. Common changes seen in urine as it decomposes are shown in the following table: Clinical Laboratory Testing - Urinalysis Urine Multistix – reading dipstick results manually; colors are matched to those on the bottle label; timing is critical for each pad. Questions  Multiple choice questions 1. Patient with diabetes mellitus have urine with: A. Decreased volume and decreased specific gravity B. Decreased volume and increased specific gravity C. Increased volume and decreased specific gravity D. Increased volume and increased specific gravity 2. Normal urine primarily consist of: A. Water, protein, and sodium B. Water, urea, and protein C. Water, urea, and sodium chloride D. Water, urea, and glucose 3. The volume of urine excreted in a 24-hour period by an adult patient was 500 ml. This condition would be termed: A. Anuria B. Oliguria C. Polyuria D. Dysuria 4. Antidiuretic hormone regulates the reabsorption of: A. Water B. Glucose C. Potassium D. Calcium 5. A woman in her ninth month of pregnancy has a urine sugar that is negative with the urine reagent strip but gives a positive reaction with the copper reduction method. The sugar most likely responsible for these results is: A. Maltose B. Galactose C. Glucose D. Lactose Oliguria is when volume of urine is equal to ………. mL/day: (A)800-2000 (B) 2500-3000 (C) 200-500 (D) 100-125 Anuria is when volume of urine is equal to ………. mL/day: (A)800-2000 (B) 2500-3000 (C) 200-500 (D) 100-125 Polyuria is when volume of urine is equal to ………. mL/day: (A)800-2000 (B) 2500-3000 (C) 200-500 (D) 600-800 Diabetes mellitus is associated with ………………. (A) Oliguria (B) Physiological polyuria (C) Pathological polyuria (D) Anuria Normal urine specific gravity collected over 24-hour ranges from: (A) 900-1000 (B) 1000 (C) 1000-1025 (D) 1040 Normally, urine pH is about (A) 2-3 (B) 4-5 (C) 5.5-6.5 (D) 7-8 Specific gravity is decreased in cases of diluted urine as in …………….. (A)Diabetes mellitus (B) Diabetes insipidus (C) Nephrotic syndrome (D) Dehydration Foul smell in urine is due to …………………….. (A)Ketonuria (B) Infections of bacteria (C) Diabetes mellitus (D) Diabetes insipidus Brown color of urine is due to ……………………. (A)Jaundice (B) Alkaptonuria (C) Diabetes mellitus (D) Hematuria Acidic urine is seen in all the following EXCEPT: (A)Metabolic acidosis (B) Respiratory alkalosis (C) Diabetic ketoacidosis (D) Severe exercise Non-Protein Nitrogenous constituents (NPN) include all the following EXCEPT: (A) Urea. (B) Ammonia (C) Creatinine (D) Glucose …………… is used in kidney function tests (A)Urea (B) Ammonia (C) Creatinine (D) Glucose Inorganic constituents of urine include all the following EXCEPT: (A)Urea (B) Chlorides (C) Phosphates (D) Carbonates Abnormal constituents of urine include all the following EXCEPT: (A) Glucose (B) Bile pigments (C) Blood (D) Sulphates Abnormal constituents of urine include: (A) Proteins (B) Urea (C) Ammonia (D) Creatinine Multiple myeloma is characterized by the presence of …… in urine: (A) Glucose (B) Albumin (C) Tam Horsfall mucoprotein (D) Bence-Jones proteins A normal renal threshold of glucose is about: (A) 180 mg/dl (B) 30 mg/dl (C) 120 mg/dl (D) 240 mg/dl Normal urine proteins include all the following EXCEPT: (A)Albumin in small amounts (B) Globulin in small amounts (C) Mucoproteins (D) Fibrinogen The excess ketone bodies in urine (ketonuria) is mainly associated with ……….. (A)Diabetes mellitus (B) Diabetes insipidus (C) Infections of bacteria (D) Jaundice Causes of urinary calculi include all the following EXCEPT: (A) Excess vitamin D (B) Excess vitamin C (C) Deficiency of vitamin A (D) Deficiency of vitamin C Causes of urinary calculi include the following: (A) Hyperparathyroidism (B) Hypoparathyroidism (C) Excess vitamin A (D) Deficiency of vitamin C  Complete: 1. The …………. is the organ responsible for excretion of urine. 2. Urine is formed within the functional unit of kidneys called ………. 3. Nephrons consist of …………… and ………………. 4. Mechanisms of urine formation include three steps which are: 1. ……………………………………………….. 2. ……………………………………………….. 3. ……………………………………………….. 5. Diabetes insipidus is due to lack of …………………. 6. The color of urine is due to 2 pigments ………….. and …………….. 7. Normally, the aspect (appearance) of freshly voided urine is …………