Podcast
Questions and Answers
What is the most common urological cause of high colored urine?
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.
Increased beetroot intake can result in a positive dipstick test for blood in urine.
False (B)
What happens to the urine color if a myoglobin presence is indicated?
What happens to the urine color if a myoglobin presence is indicated?
The color fades.
If the urine is ______, further investigation is needed.
If the urine is ______, further investigation is needed.
Match the following findings with their corresponding characteristics:
Match the following findings with their corresponding characteristics:
What is the formula for calculating clearance?
What is the formula for calculating clearance?
What is a factor that influences serum creatinine (S.Cr) levels?
What is a factor that influences serum creatinine (S.Cr) levels?
Cystatin C levels are not affected by diet or race.
Cystatin C levels are not affected by diet or race.
Serum creatinine levels begin to rise immediately after the onset of acute kidney injury (AKI).
Serum creatinine levels begin to rise immediately after the onset of acute kidney injury (AKI).
What happens to the single nephron GFR when the number of nephrons decreases?
What happens to the single nephron GFR when the number of nephrons decreases?
What is the relationship between serum creatinine and glomerular filtration rate (GFR)?
What is the relationship between serum creatinine and glomerular filtration rate (GFR)?
Cystatin C is a __________ molecule protein.
Cystatin C is a __________ molecule protein.
Match the following factors with their effects on Cystatin C levels:
Match the following factors with their effects on Cystatin C levels:
At a GFR of approximately 60 mL/min, the serum creatinine level is approximately _____ mg/dL.
At a GFR of approximately 60 mL/min, the serum creatinine level is approximately _____ mg/dL.
Match the following factors with their effect on serum creatinine levels:
Match the following factors with their effect on serum creatinine levels:
Which equation is considered obsolete for estimating GFR?
Which equation is considered obsolete for estimating GFR?
Pregnancy is the only condition where high creatinine values are significant independently.
Pregnancy is the only condition where high creatinine values are significant independently.
What is the primary usage of the KD-EPI equation?
What is the primary usage of the KD-EPI equation?
The ___ equation is used to estimate GFR in children.
The ___ equation is used to estimate GFR in children.
Match the following equations with their characteristics:
Match the following equations with their characteristics:
Which of the following urinary conditions signifies significant proteinuria?
Which of the following urinary conditions signifies significant proteinuria?
The urine dipstick test can accurately detect proteinuria levels above 800 mg/day.
The urine dipstick test can accurately detect proteinuria levels above 800 mg/day.
What is the effect of increased afferent arteriolar dilation on glomerular filtration rate (GFR)?
What is the effect of increased afferent arteriolar dilation on glomerular filtration rate (GFR)?
Efferent arteriolar constriction results in an increased GFR.
Efferent arteriolar constriction results in an increased GFR.
What condition is indicated by a urinary albumin level of 300 mg/day?
What condition is indicated by a urinary albumin level of 300 mg/day?
What role do prostaglandins play in renal physiology?
What role do prostaglandins play in renal physiology?
Elevated levels of urine protein can be caused by ______, inflammation, and tubular injury.
Elevated levels of urine protein can be caused by ______, inflammation, and tubular injury.
Match the following tests with what they measure:
Match the following tests with what they measure:
The use of ___________ inhibitors can lead to efferent arteriolar dilatation, increasing GFR.
The use of ___________ inhibitors can lead to efferent arteriolar dilatation, increasing GFR.
Match the conditions with their effects on GFR:
Match the conditions with their effects on GFR:
What is the effect of NSAIDs on glomerular filtration rate?
What is the effect of NSAIDs on glomerular filtration rate?
The kidney benefits from a decreased efferent arteriole.
The kidney benefits from a decreased efferent arteriole.
What happens to renal blood flow when cardiac output increases?
What happens to renal blood flow when cardiac output increases?
Which of the following odors is associated with Tyrosinemia type 1?
Which of the following odors is associated with Tyrosinemia type 1?
The normal urine pH is typically around 4-4.5.
The normal urine pH is typically around 4-4.5.
What is the urine specific gravity range considered normal?
What is the urine specific gravity range considered normal?
An acidic urine pH (> 5.5) for 3 days may indicate __________.
An acidic urine pH (> 5.5) for 3 days may indicate __________.
Match the following odors with their associated conditions:
Match the following odors with their associated conditions:
What is the primary mechanism of renal autoregulation that responds to changes in blood pressure?
What is the primary mechanism of renal autoregulation that responds to changes in blood pressure?
An increase in GFR leads to an increase in the reabsorption of sodium by the kidneys.
An increase in GFR leads to an increase in the reabsorption of sodium by the kidneys.
What is the formula to calculate Filtration Fraction (FF)?
What is the formula to calculate Filtration Fraction (FF)?
In the theory of pressure natriuresis, an increase in cardiac output leads to an increase in excretion of _____ and _____.
In the theory of pressure natriuresis, an increase in cardiac output leads to an increase in excretion of _____ and _____.
Match the conditions to their effects on afferent arterioles:
Match the conditions to their effects on afferent arterioles:
Which type of red blood cell is characterized as 'mickey mouse RBCs'?
Which type of red blood cell is characterized as 'mickey mouse RBCs'?
Urinary tract infections (UTIs) have high sensitivity and poor specificity in dipstick tests.
Urinary tract infections (UTIs) have high sensitivity and poor specificity in dipstick tests.
Name one factor that can affect the leukocyte urine dipstick test.
Name one factor that can affect the leukocyte urine dipstick test.
The presence of ______ in urine analysis may be indicative of extravascular hemolysis.
The presence of ______ in urine analysis may be indicative of extravascular hemolysis.
Match the following dipstick tests with their respective parameters:
Match the following dipstick tests with their respective parameters:
Which condition is associated with euglycemic glycosuria?
Which condition is associated with euglycemic glycosuria?
SGLT 2 inhibitors are associated with euglycemic ketosis.
SGLT 2 inhibitors are associated with euglycemic ketosis.
What is the primary purpose of urine dipstick analysis?
What is the primary purpose of urine dipstick analysis?
What is the recommended storage temperature for urine samples?
What is the recommended storage temperature for urine samples?
A darkening of the urine after standing for a long time can be caused by triampterene.
A darkening of the urine after standing for a long time can be caused by triampterene.
What type of urine sample is preferred for analysis?
What type of urine sample is preferred for analysis?
The presence of a pungent odour in urine is often a sign of __________.
The presence of a pungent odour in urine is often a sign of __________.
Match the urine color with its associated condition:
Match the urine color with its associated condition:
What should be avoided prior to urine collection to ensure accurate results?
What should be avoided prior to urine collection to ensure accurate results?
Collecting urine from a urobag is an appropriate method for obtaining a sample.
Collecting urine from a urobag is an appropriate method for obtaining a sample.
What odour is characteristic of Maple Syrup Urine Disease (MSUD)?
What odour is characteristic of Maple Syrup Urine Disease (MSUD)?
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.
