Flashcards in Urinalysis Deck (71)
What are 5 things that can cause urine to be turbid?
What are the 10 components on a dipstick?
2. Specific gravity
8. leukocyte esterase
What is a normal urine pH?
What happens to urine pH if it isn't properly stored/stored for too long?
becomes more alkaline
What are 3 causes of acidic urine?
- high protein diet
- metabolic acidosis
- respiratory acidosis
What are 5 causes of alkaline urine?
- vegetarian or high citrus diet
- metabolic alkalosis
- respiratory alkalosis
- renal tubular acidosis
- Urinary tract infection (from NH3 production)
What is the urine specific gravity a measure of?
density of the urine compared to distilled water
What is the normal range of USG?
1.003 (very dilute) to 1.035 (very concentrated)
What 3 things can cause a lower SG (<1.010)?
- increased fluid intake
- diuretic use
- diabetes insipidus
What 3 things can cause a high SG (>1.030)?
- decreased renal perfusion
What causes a fixed SG? (1.010)
severe renal disease leading to loss of concentrating/diluting ability
What does the dipstick test detect in terms of blood products? What confirmatory test do you need and why?
Detects peroxidase activity of RBCs
Myoglobin and hemoglobin will also give a + result so you need to confirm with microscopy
What can cause a false negative blood result on a dipstick?
high levels of vitamin C
What is a normal level of urinary protein excretion?
What is specifically being detected on the dipstick protein analysis?
Mostly is sensitive to albumin so mainly reflects glomerular proteinuria
- not sensitive to other proteins like tubular or Igs
How is proteinuria graded?
Trace to 4+ and is highly dependent on urine concentration
- dilute urine can underestimate proteinuria and vice versa
What cutoff of plamsa glucose is helpful in determining the cause of glucose in the urine?
- > = diabetes
- < = defect in reabsorption of glucose (Fanconi syndrome)
What 3 conditions can cause ketones to be present in the urine?
2. alcoholic ketoacidosis
Which ketone products is detected on dipstick?
Why would nitrite be present in the urine?
Nitrate converted to nitrite by bacterial nitrate reductase
= bacterial infection
What can cause a false positive nitrite in the urine?
- bacterial contamination of the sample
- delayed analysis
- improperly stored dipstick strips
What can cause a false negative nitrite?
- low nitrate diet
- insufficient urine dwell time in the bladder
- Abx use
- certain bacteria don't form nitrite (enterococci, streptococci, staph, pseudomonas)
What is leukocyte esterase?
enzyme found in neutrophils and macrophages
What does a positive LE test mean?
Presence of intact or lysed WBCs
What 3 things can cause a false negative LE test?
high urine protein, glucose, or vitamin C
When is urine microscopy ordered?
When you have atypical dipstick results or if the macroscopic exam of the urine looks abnormal
What is a normal RBC count on microscopy?
What causes crenation of RBCs?
hypertonic urine drawing water out and causing deformities
What should be suspected if you see dysmorphic RBCs on microscopy?