L5: Urinalysis Flashcards
how to get a clean “catch”
clean nonfoaming disenfectant, allow to dry
discard first voided portion as it may contain urethral contaminants, collect midstream speciman
Dark brown→ black urine
bile/bilirubin due to liver/bile disease
turbidity causes
Crystal precipitation of amorphous material, bacteria, yeast, WBCs, RBCs, mucus, squamous epithelial cells, sperm prostatic fluid, lipids
bile/bilirubin due to liver/bile diseases that can cause brown/black urine
alkaptonuria: lack of homogentisic acid oxidase
malignant melanoma: melanogen
ash tray smell to urine
cigarrete smokers
fruity smell to urine
ketone bodies
putrid, foul smelling urine
bacteria of UTI
Amino acid disorders that change urine smell
Phenylketonuria
Maple syrup urine disease
Normal pH
4.5-8
Urine pH reflects
serum pH
acidic urine pH
4.5-5.5
alkaline urine pH
6.-8.0
Specific gravity
Concentration/weight of dissolved solutes
Ability of kidney to concentrate and dilute urine
normal Specific gravity
1.003-1.035
Isosthenuria
Fixed at 1.010→ kidney disease
→ same SG as initial plasma
normal urine volume
500CC-2000CC/24 hours
oliguria
<500 CC/24 hours
anuria
<100 CC/24 hours
polyuria
Excessive amounts, dilute, SG=1.0-1.002
When does glucose appear in the urine
plasma glucose >150-180 mg/dL exceed renal threshold
false negatives for glucose
ascorbic acid, aspirin
Ketones are
Products of incomplete fat metabolism when carbohydrate stores are diminished
When are ketones present
acidosis: DKA, rapid weight loss, fasting, starvation, pregnancy
Proteins are mostly
albumin
reflect renal endothelial function
Elevated proteins indicate
Early sign of kidney disease
proteins are overestimated in
concentrated urine
proteins are underestimated in
dilute urine
proteins false positive due to
pyridium
can moderately increased albumin be detected by a urine dipstick?
No
Must perform a special test
If a patient has persistently positive proteins on dipstick, the next step is to
quantify albumin:
abumin: creatinine ration
24 hour urine sample
high risk patients to screen for moderately increased albumin
DM
HTN
CVD
causes of blood in urine
hemoglobin or myoglobin
have to centrifuge to determine which
false negatives when hematuria is present
ascorbic acids
hematuria testing sensitivity
5-10 RBC/ .05-.3 mg/DL of hemoglobin
nitrite is produced by
enterobacteriaceae that reduce nitrates→ nitrite
nitrite indicates
UTI
false negatives for nitrite
urine in bladder < 4 hours
different bacteria don’t have enzymes
leukocyte esterase
Released by lysed neutrophils and macrophages
leukocyte esterase + nitrate both positive
increased sensitivity for UTI
false positives for leukocyte esterase
vaginal contamination, trichomonas
bilirubine and urobilinogen
Used in conjunction to determine pathology
Both normally negative
bilirubin turns urine
brown
Hemolytic disease findings
(-) bilirubin
Increased urobilinogen
Hepatic disease findings
(+/-) bilirubin
Increased urobilinogen