Medicine Marrow Pg No 735-744 (Nephrology)
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Medicine Marrow Pg No 735-744 (Nephrology)

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Questions and Answers

What is the most common urological cause of high colored urine?

  • Carcinoma bladder (correct)
  • Intravascular hemolysis
  • Nephrological disorders
  • Porphyria

    • Increased beetroot intake can result in a positive dipstick test for blood in urine.

    False

    What happens to the urine color if a myoglobin presence is indicated?

    The color fades.

    If the urine is ______, further investigation is needed.

    <p>high colored</p> Signup and view all the answers

    Match the following findings with their corresponding characteristics:

    <p>Glomerular Hematuria = ≥ 40% dysmorphic RBCs Rhabdomyolysis = Short half-life myoglobin Hemolysis = Persistent hemoglobin IgA nephropathy = Mesangial proliferation + matrix expansion</p> Signup and view all the answers

    What is the formula for calculating clearance?

    <p>Clearance = Urine concentration × Volume / Plasma concentration</p> Signup and view all the answers

    What is a factor that influences serum creatinine (S.Cr) levels?

    <p>Both B and C</p> Signup and view all the answers

    Cystatin C levels are not affected by diet or race.

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

    Serum creatinine levels begin to rise immediately after the onset of acute kidney injury (AKI).

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

    What happens to the single nephron GFR when the number of nephrons decreases?

    <p>Single nephron GFR increases to maintain GFR.</p> Signup and view all the answers

    What is the relationship between serum creatinine and glomerular filtration rate (GFR)?

    <p>Inverse relationship</p> Signup and view all the answers

    Cystatin C is a __________ molecule protein.

    <p>13 kDa</p> Signup and view all the answers

    Match the following factors with their effects on Cystatin C levels:

    <p>Inflammation = Non-specific elevation Taking steroids = Non-specific elevation Smokers = Non-specific elevation Normal conditions = No effect</p> Signup and view all the answers

    At a GFR of approximately 60 mL/min, the serum creatinine level is approximately _____ mg/dL.

    <p>2</p> Signup and view all the answers

    Match the following factors with their effect on serum creatinine levels:

    <p>Lower Muscle Mass = Decreases S.Cr levels Age over 40 = Increases S.Cr levels High Protein Diet = Increases S.Cr levels Obesity = No effect on S.Cr levels</p> Signup and view all the answers

    Which equation is considered obsolete for estimating GFR?

    <p>Cockroft &amp; Gault equation</p> Signup and view all the answers

    Pregnancy is the only condition where high creatinine values are significant independently.

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

    What is the primary usage of the KD-EPI equation?

    <p>To estimate GFR, especially when GFR is greater than 60.</p> Signup and view all the answers

    The ___ equation is used to estimate GFR in children.

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

    Match the following equations with their characteristics:

    <p>Cockroft &amp; Gault = Obsolete and overestimates GFR MDRD = Uses standard assays for estimation CKD-EPI = Best for GFR &gt; 60 Schwartz = Estimates GFR in children</p> Signup and view all the answers

    Which of the following urinary conditions signifies significant proteinuria?

    <p>500 mg/day</p> Signup and view all the answers

    The urine dipstick test can accurately detect proteinuria levels above 800 mg/day.

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

    What is the effect of increased afferent arteriolar dilation on glomerular filtration rate (GFR)?

    <p>Increases GFR</p> Signup and view all the answers

    Efferent arteriolar constriction results in an increased GFR.

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

    What condition is indicated by a urinary albumin level of 300 mg/day?

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

    What role do prostaglandins play in renal physiology?

    <p>They promote afferent arteriolar dilation.</p> Signup and view all the answers

    Elevated levels of urine protein can be caused by ______, inflammation, and tubular injury.

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

    Match the following tests with what they measure:

    <p>24-hour urine protein = Total protein excreted in 24 hours Spot urine PCR = Ratio of protein to creatinine Spot urine ACR = Ratio of albumin to creatinine Urine dipstick test = Qualitative test for high protein levels</p> Signup and view all the answers

    The use of ___________ inhibitors can lead to efferent arteriolar dilatation, increasing GFR.

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

    Match the conditions with their effects on GFR:

    <p>Increased Afferent = Increased GFR Decreased Afferent = Decreased GFR Increased Efferent = Decreased GFR Decreased Efferent = Increased GFR</p> Signup and view all the answers

    What is the effect of NSAIDs on glomerular filtration rate?

    <p>Decrease GFR by blocking prostaglandins</p> Signup and view all the answers

    The kidney benefits from a decreased efferent arteriole.

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

    What happens to renal blood flow when cardiac output increases?

    <p>Renal blood flow increases.</p> Signup and view all the answers

    Which of the following odors is associated with Tyrosinemia type 1?

    <p>Cabbage-like</p> Signup and view all the answers

    The normal urine pH is typically around 4-4.5.

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

    What is the urine specific gravity range considered normal?

    <p>1.020-1.040</p> Signup and view all the answers

    An acidic urine pH (> 5.5) for 3 days may indicate __________.

    <p>Type-1 Renal Tubular Acidosis (RTA)</p> Signup and view all the answers

    Match the following odors with their associated conditions:

    <p>Fish urine = Cystinuria Sulfurous = Beta Ketothiolase deficiency Acid smell = Trimethylaminuria Cat urine = Methyl malonic acidemia (MMA)</p> Signup and view all the answers

    What is the primary mechanism of renal autoregulation that responds to changes in blood pressure?

    <p>Tubuloglomerular feedback</p> Signup and view all the answers

    An increase in GFR leads to an increase in the reabsorption of sodium by the kidneys.

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

    What is the formula to calculate Filtration Fraction (FF)?

    <p>FF = GFR / Renal plasma flow (RPF)</p> Signup and view all the answers

    In the theory of pressure natriuresis, an increase in cardiac output leads to an increase in excretion of _____ and _____.

    <p>Na+, H2O</p> Signup and view all the answers

    Match the conditions to their effects on afferent arterioles:

    <p>Decreased GFR = Afferent arteriolar vasodilation Increased GFR = Afferent arteriolar vasoconstriction</p> Signup and view all the answers

    Which type of red blood cell is characterized as 'mickey mouse RBCs'?

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

    Urinary tract infections (UTIs) have high sensitivity and poor specificity in dipstick tests.

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

    Name one factor that can affect the leukocyte urine dipstick test.

    <p>Concentrated urine</p> Signup and view all the answers

    The presence of ______ in urine analysis may be indicative of extravascular hemolysis.

    <p>red blood cells</p> Signup and view all the answers

    Match the following dipstick tests with their respective parameters:

    <p>Leukocytes = Infection indication Nitrites = Bacterial infection detection Protein = Kidney damage assessment Glucose = Diabetes mellitus indication</p> Signup and view all the answers

    Which condition is associated with euglycemic glycosuria?

    <p>Proximal RTA</p> Signup and view all the answers

    SGLT 2 inhibitors are associated with euglycemic ketosis.

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

    What is the primary purpose of urine dipstick analysis?

    <p>To screen for various substances and indicators of health in urine.</p> Signup and view all the answers

    What is the recommended storage temperature for urine samples?

    <p>2-8°C</p> Signup and view all the answers

    A darkening of the urine after standing for a long time can be caused by triampterene.

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

    What type of urine sample is preferred for analysis?

    <p>First morning midstream urine sample</p> Signup and view all the answers

    The presence of a pungent odour in urine is often a sign of __________.

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

    Match the urine color with its associated condition:

    <p>Light yellow = Normal Pink = Increased water intake Green = Impemenem + cilastatin Brown = Triamterene</p> Signup and view all the answers

    What should be avoided prior to urine collection to ensure accurate results?

    <p>Strenuous physical activity</p> Signup and view all the answers

    Collecting urine from a urobag is an appropriate method for obtaining a sample.

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

    What odour is characteristic of Maple Syrup Urine Disease (MSUD)?

    <p>Curry or maple syrup</p> Signup and view all the answers

    Study Notes

    High Colored Urine

    • Most commonly caused by carcinoma bladder (90%)
    • Nephrological causes contribute 9%
    • Hematological causes are rare (1%)
    • Dipstick test is used to identify blood in the urine
    • If the dipstick test is negative, porphyria or increased beetroot intake may be considered
    • Urine centrifugation helps to differentiate between hemoglobin/myoglobin and RBC sedimentation
    • Persistent high urine color after 3-6 hours suggests hemoglobinuria (long half-life)
    • Fading urine color over 3-6 hours indicates myoglobinuria (short half-life)
    • Examination of urine sediment can help identify glomerular hematuria
    • Glomerular hematuria is characterized by a high percentage of dysmorphic RBCs, acanthocytes, and single RBC casts

    Disadvantages of Serum Creatinine

    • Serum creatinine levels rise 24-48 hours after the onset of acute kidney injury (AKI)
    • Muscle mass, race, age, and sex affect S.Cr levels due to their impact on muscle mass
    • Diet, including protein supplementation and malnutrition, can influence S.Cr levels
    • Obesity does not affect S.Cr
    • Certain medications like cimetidine and trimethoprim interfere with creatinine tubular secretion

    Creatinine and GFR Relationship

    • There is an inverse relationship between serum creatinine and glomerular filtration rate (GFR)
    • As serum creatinine levels increase, GFR decreases significantly

    Renal Physiology

    • GFR is determined by the single nephron GFR and the number of nephrons
    • If the number of nephrons decreases, SNGFR increases to maintain GFR, leading to hyperfiltration injury
    • If this compensation fails, intraglomerular hypertension, increased proteinuria, interstitial fibrosis, and reduced GFR occur

    Endogenous Creatinine Clearance

    • Clearance is calculated by multiplying urine concentration by urine volume in ml/min and dividing by plasma concentration

    Cystatin C

    • A 13 kDa protein that inhibits cysteine protease
    • Filtered but not secreted by the kidney
    • Reabsorbed by the proximal convoluted tubule (PCT)
    • Produced at a constant rate by all nucleated cells
    • Advantages: unaffected by race and diet
    • Disadvantages: non-specifically elevated in inflammation, steroid use, and smokers; cannot replace creatinine as a GFR marker

    Glomerular Hemodynamics

    • Increase cardiac output leads to increased renal blood flow, followed by decreased renal blood flow due to increased renal interstitial hydrostatic pressure and water reabsorption from the PCT
    • Afferent arteriolar constriction reduces GFR, whereas dilation increases GFR
    • Efferent arteriolar constriction increases GFR, while dilation reduces GFR
    • Prostaglandins induce afferent arteriolar dilatation
    • Angiotensin II constricts efferent arterioles
    • Reduced efferent arteriolar constriction leads to increased blood flow to the medulla, potentially causing medullary hypoxia
    • ACE inhibitors benefit nephrology patients by reducing angiotensin II, dilating efferent arterioles, and increasing GFR and blood flow
    • ACE inhibitors are contraindicated in patients with bilateral renal artery stenosis because the afferent arteriole is not functional
    • NSAIDs block prostaglandins, causing afferent arteriolar constriction and reduced GFR
    • ACE inhibitors in patients already on ACE-I can lead to efferent arteriolar constriction, potentially causing renal failure

    Creatinine

    • The best marker for estimating GFR
    • Produced in muscle from creatine
    • Lower creatinine levels in individuals with reduced muscle mass (e.g., amputation)
    • Pregnancy is the only condition where high creatinine values are significant.
    • 113 kDa molecule

    Equations to Calculate GFR

    • Cockroft-Gault equation: obsolete, overestimates GFR
    • MDRD equation: developed by the society for modification of diet and renal diseases
    • CKD-EPI equation: developed by the Chronic Kidney Disease Epidemiology Collaboration, preferred for GFR > 60.
    • Schwartz equation: used for estimating GFR in children

    Proteinuria

    • Condition characterized by protein detected in urine
    • Significant proteinuria is defined as > 500 mg/day
    • In pregnancy, significant proteinuria is > 300 mg/day
    • Albuminuria is defined as > 300 mg/day of urinary albumin
    • Elevated urine protein can be caused by tubular injury, inflammation, TGF-β, fibrosis, stress, anxiety, menses, and protein supplements

    Tests for Proteinuria

    • 24-hour urine protein: measures total protein excreted in 24 hours
    • Spot urine protein-creatinine ratio (PCR): measures the ratio of protein to creatinine in a urine sample
    • Spot urine albumin-creatinine ratio (ACR): measures the ratio of albumin to creatinine in a urine sample
    • Urine dipstick test: a quick, qualitative test that is only positive for high proteinuria (~800 mg) and detects only albumin

    Urine Analysis

    • Urine odor can indicate specific conditions: cabbage-like (tyrosinemia type 1), rancid butter (MCD), cat urine (MMA), acid smell (trimethylaminuria), fishy (cystinuria), sulfurous (Beta Ketothiolase deficiency), sweet (Hawkinsinuria), and swimming pool
    • Urine pH is typically 4-4.5 (acidic)
    • Urine specific gravity is 1.020-1.040
    • Urine osmolality is 800-900
    • Abnormal values suggest specific conditions: Urine pH > 5.5 for 3 days + normal RFT (type-1 RTA), urine specific gravity < 1.005 (diabetes insipidus), and urine osmolality < 600 (Diabetes insipidus)

    Regulation of Renal Function

    • Renal autoregulation maintains constant renal blood flow and GFR within a range of mean arterial pressure (MAP) of 80-180 mmHg
    • The mechanism involves the myogenic reflex (stretch reflex) and the tubuloglomerular feedback (adenosine-mediated)
    • Glomerulotubular balance compensates for changes in GFR by adjusting reabsorption
    • Filtration fraction (FF) is the ratio of GFR to renal plasma flow (RPF)
    • Elevated FF increases peritubular capillary oncotic pressure, contributing to fluid reabsorption from the interstitial space
    • The theory of pressure natriuresis explains that increased cardiac output leads to increased sodium and water excretion, potentially contributing to blood pressure control

    Urine Analysis

    • Urine collection should be done with a first morning midstream urine sample
    • Analyze the sample within 2-4 hours at room temperature
    • Preserve the sample with formaldehyde or glutaraldehyde
    • Store the sample at 2-8°C for up to 12 hours
    • Avoid strenuous physical activity 72 hours before urine collection
    • Avoid collecting urine during menstruation
    • Collect fresh urine from catheterized patients
    • Do not collect urine from a urobag

    Urine Appearance

    • Normal urine is light yellow
    • Pale or white urine suggests increased water intake
    • Darkening on long standing may be due to desferrioxamine or beetroot
    • Green urine can be caused by imipenem + cilastatin
    • Brown urine may be due to triamterene
    • Orange urine can be caused by nitrofurantoin, rifampicin, or entacapone.

    Urine Odor

    • Pungent odor: infection (due to ammonia production by bacteria)
    • Musty/mousy odor: phenylketonuria
    • Curry/maple syrup odor: maple syrup urine disease (MSUD)
    • Sweaty feet odor: isovaleric acidemia, glutaric aciduria type II

    Types of RBCs in Urine

    • Urological conditions: crenated, isomorphic, and dysmorphic red blood cells
    • Nephrological conditions: acanthocytes (mickey mouse RBCs)

    Dipstick Parameters

    • The document provides a visual representation of the color-coded results for various dipstick parameters, including leukocytes, nitrites, urobilinogen, protein, pH, blood, specific gravity, ketones, conjugated bilirubin, and glucose.

    Clinical Conditions

    • Urinary tract infections (UTIs): high specificity, poor sensitivity
    • Extravascular hemolysis
    • Proximal RTA: Euglycemic glycosuria
    • SGLT 2 inhibitors: Euglycemic Ketosis

    Factors Affecting Leucocyte Urine Dipstick Test

    • Concentrated urine
    • High relative density
    • Proteinuria
    • Glucosuria

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    Description

    Test your knowledge on the causes of high colored urine and the disadvantages of serum creatinine as a marker for kidney function. This quiz covers aspects such as bladder carcinoma, nephrological causes, and the effects of muscle mass on serum creatinine levels. Dive into the details of urine analysis and the interpretation of dipstick tests.

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