Urinalysis Flashcards
Normal urine pH
4.5 - 8.6
What is specific gravity and appropriate range
How concentrated the urine is
Ranges from 1.005-1.030 for humans
What is leukocyte esterase
detects an enzyme present in WBC’s and is used as a screen for infection
What is the nitrites test
nitrates in the urine are converted to nitrites by some common UTI pathogens like E. coli and Klebsiella. A positive test with a positive leukocyte esterase is suggestive of a UTI
Which type of bilirubin is normally in urine
conjugated bilirubin
What is urobilinogen
created by gut bacteria from excreted bilirubin breakdown products in the feces. Urobilinogen is colorless and will be increased with any bowel stasis or obstruction or bacterial overgrowth, and absent when there is a complete obstruction or inability to excrete bile into the lumen of the gut, as in congenital biliary atresia.
Significance of occult blood test results
looks for heme-containing proteins and will react with hemoglobin but ALSO with myoglobin, since myoglobin is a heme-containing protein
If there are no RBC’s, then students should be thinking about rhabdomyolysis or hemolysis as a cause for this combination of findings.
What are acanthocytes
(look like a numeral 8 due to membrane blebbing) are always attributed to being from an abnormality of the glomerulus, as the osmotic changes in the nephron cause the cells to assume bizarre shapes
What can cause WBCs in urine
Anything that causes inflammation of the kidney or the bladder can cause these, not just infection.
A special stain can be done to look for eosinophils; eosinophils in the urine are very suggestive of allergic tubulointerstitial nephritis
What are casts
Casts are tubular-shaped structures that form when Tamm-Horsfall protein the urine captures other types of sediment in the urine, forms a mold of an individual urinary tubule space, and then is shed into the urine. Casts can be seen in a variety of important disease states and help confirm glomerular or other intrinsic renal or systemic diseases.
Conditions favoring stone formation
Concentrated urine
Low urine volume
High rate of excretion of the metabolic product forming the stone
Changes in pH of the urine
Urinary stagnation due to obstruction to urinary outflow
Most common component of stone
Calcium
Which stones are not radioopaque
Uric acid stones
Type of stone that forms “staghorn” calculi that are very large and mold to the renal pelvis
Struvite stones
Associated with many conditions
Various cell types, advanced kidney disease
Anything that increases uric acid in the urine: urate nephropathy, uric acid stones, tumor lysis syndrome, gout
Calcium phosphate - very common
Seen in urease-producing UTI pathogens (Proteus, Klebsiella)
Staghorn calculi
Calcium Oxalate
Calcium oxalate monohydrate crystals can be seen as a clue in ethylene glycol poisoning.
Dihydrate commonly seen and not associated with specific disease
Cysteine
Diagnostic of cystinuria, associated with metabolic diseases
