SFP: urinalysis Flashcards
What are the 3 elements of urinalysis?
- Appearance (color and clarity)
- Chemical analysis on dipstick
- Microscopic exam of sediment
What is specific gravity?
Test of tubular function aka the ability to concentrate or dilute urine as needed
What things can cause proteinuria?
Glomerular disease, tumors, infection
What are pitfalls of analyzing protein in the urine?
Dipstick only measures albumin; other proteins may be missed. Very dilute urine may also cause a false negative.
How do we measure blood in the urine?
Measuring hemoglobin RBCs, and myoglobin (heme)
What is hematuria?
Red blood cells in the urine; often caused by glomerulonephritis or tumors
What is hemoglobinuria?
Hemoglobin in the urine that may be caused by intravascular hemolysis or can be from red cells lysing while sitting in the urine
At what glucose range will we start seeing it in the urine?
180-200
What can cause a false positive for glucose in the urine?
Hydrogen peroxide or hypochlorite
What can cause a false negative for glucose in the urine?
Ascorbic acid or salicylates
When do we see ketones in the urine?
Poorly controlled diabetes, starvation, prolonged vomiting, ketogenic diets
Why can ketone amounts be underestimated with dipstick?
Some dipsticks measure acetoacetates but not acetone or hydroxybutyric acid
What is normal urine pH?
5.0-6.0
What causes alkaline urine?
Right after meals, systemic alkalosis, proteus infection (urea splitting bacteria), renal tubular acidosis
What causes acidic urine?
Ketosis and systemic acidosis
What could increased bilirubin on dipstick indicate?
Liver dysfunction, biliary tract obstruction
What is urobilinogen?
A breakdown product of bilirubin produced by degradation via gut bacteria.
Does dipstick pick up decreased or elevated levels of urobilinogen?
Increased
When might we see increased urobilinogen?
Increased hemolysis, cirrhosis, or severe hepatitis
What would nitrite or leukocyte esterase tell us on dipstick?
Bacterial infection
How is urinary sediment obtained?
If there is 10 ccs or urine, we centrifuge it and pour off 9. The remaining 1 cc is agitated to suspend the sediment. A drop is then placed on a slide.
What can we see when examining urinary sediment?
RBCs, WBCs, bacteria, yeast, casts, crystals
Where are casts formed?
Renal tubular lumens
what kind of crystals are in alkaline urine
phosphate
what kind of crystals are in acidic urine
urates and cysteine
___ cells are sometimes shed from the urethra
squamous
what are hyaline casts
they’re “ghost-like” casts that may be seen in normal conditions or during proteinuria
What do red cell casts indicate?
Renal infarct, glomerulonephritis; injury coming from the tubule/glomerulus
What do white cell casts tell us?
there is some kind of infection coming from the kidney; can help distinguish pyelonephritis from cystitis
What do epithelial cell casts indicate?
Acute tubular injury occurred
What do granular casts indicate?
Degenerated epithelial or WBC casts
What do waxy casts indicate?
Chronic renal failure
what are fatty casts?
casts seen in nephrotic syndrome with a maltese-cross appearance
what are hemoglobin casts?
casts from massive internal hemolysis; ex is incompatible blood transfusion
when do we see triple phosphate crystals
infections such as proteus
what is this
cysteine crystal
what is this
leucine crystal associated with maple syrup/liver disease
what is this
crystals from sulfa drugs
what is this
uric acid crystal; seen in gout or sometimes normal urine
what is this
calcium oxalate crystal; normal people or ethylene glycol poisoning!!
what is this
ammonium biurate crystal from urine sitting for a while
