Urinalysis: Part 1

Timing Random –Collected without regard to time First morning (void) ----Most concentrated 24-hour or timed

Source/collection Catheterized -Tube inserted into bladder via urethra Midstream clean-catch -Best for urine cultures -Clean external meatus (urethral opening) -Discard initial void, then collect sample Suprapubic – percutaneous syringe aspirate -directly from bladder Pediatric -U-Bag -Adhesive attachment around perineum

Biohazard substance? — use standard precautions Container: clean, dry, leak-proof, wide-mouth, plastic Minimum 10-12 ml (manual procedures) —-Must be standardized w/in institution Tested within 2 hours, otherwise refrigerate —–Loss of formed elements and cells Chemical preservatives available, must check test requirements first (esp. dip and culture)

Color – darkens or changes (esp. bilirubin/urobilinogen) Clarity – decreases (xtal, ppt formation, bacterial growth) RBCs and WBCs lyse (alkaline or dilute) Casts dissolve (alkaline or dilute) Bacteria – increase by exponential growth pH – increase (urea hydrolyzed to NH3 by bacteria) Glucose – decrease (bacteria, yeast, cell consumption) Ketones – decrease (acetone evaporation, AcOAc brkdn) Bilirubin and urobilinogen - decrease —Oxidative and photo-decomposition Nitrite – increase (bacterial conversion of nitrates)

Evaluate using well-mixed urine, through a clear container, against white background with adequate room lighting: Color Clarity Odor Concentration by Specific Gravity Volume

yellow urochrome

recent fluid consumption, polyuria or diabetes insipidus, diabetes mellitus

concentrated specimen, ingestion of carrots or vitamin A, presence of pyridium or bilirubin

Bilirubin oxidized to biliverdin

RBCs, hemoglobin, myoglobin , porphyrins, beets, menstrual contamination

RBCs, Hgb oxidized to metHgb, myoglobin, homogentisic acid (alkaptonuria), melanin

Purple discoloration can occur in alkaline urine as a result of the degradation of indoxyl sulfate (indican), a metabolite of dietary tryptophan, into indigo (which is blue) and indirubin (which is red) by bacteria such asProvidencia stuartii, Klebsiella pneumoniae, P. aeruginosa, Escherichia coli,and enterococcus species.

Normal urine should be clear Hazy, cloudy, turbid and milky due to pathologic or nonpathologic causes: —-Crystals, precipitate or calculi (stones) —-RBCs, WBCs (pyuria), bacteria, yeast, sperm, fat —-Prostatic fluid, mucous threads —-X-ray media, fecal contamination —-Chyluria – lymph (chyle) in urine

Normal: faintly aromatic Ammoniacal/foul: may indicate presence of bacteria due to UTI, improper storage Sweet, fruity: may indicate presence of ketone bodies due to diabetes mellitus, starvation, strenuous exercise, vomiting, diarrhea, malnutrition Maple syrup: maple syrup urine disease Genetic defect in Leu, Ile, Val (BCAAs) metabolism

Function of solutes present and volume excreted Expressed as specific gravity or osmolality Specific gravity: ratio of the density of urine to the density of an equal volume of pure water SG measured directly or indirectly • —Indirect: refractometer, reagent strip • —–Direct: urinometer (rarely used)

Ranges: 1.002-1.040 • Kidney cannot concentrate >1.040 • ——–Renal medulla max. SG ~1.040 • Most commonly 1.010-1.025 (glom. filtrate ~1.010) Low SG (hyposthenuric): • diabetes insipidus • renal tubular disease - kidney cannot concentrate urine High SG (hypersthenuric): • DM • fever, vomiting, diarrhea (causing dehydration) • radiographic dyes, mannitol (esp. if >1.040)

Normal: 600-2000 mL/day Polyuria: >2 L/day: excessive liquid intake, diabetes mellitus or insipidus Oliguria:

Leukocyte Esterase Nitrite Urobilinogen Protein pH Blood Specific Gravity Ketones Bilirubin Glucose

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Significance (increases only) • –Diabetes mellitus • –Renal glycosuria – lowered renal threshold • ——-Renal disease • ———-Pregnancy (5-10% of cases) Limitations • –Interference: reducing agents (esp. vitamin C) • ———-False negative or decrease • –Only measures glucose and not other sugars. • –Renal threshold (normally 160-180 mg/dL) must be passed in order for glucose to appear in the urine. Other Tests CuSO4 test for other reducing sugars (Clinitest, Benedict’s test). —Galactose, fructose, xylose, maltose, lactose —Not sucrose

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Significance Increased direct bilirubin in plasma Indirect is bound to albumin and normally not filtered Elevated in most liver disease except ----Pre-hepatic jaundice ----Gilberts syndrome -----Crigler-Najjar syndromes Limitations Decreased by prolonged exposure of sample to light False positives with red-colored drugs in urine Confirm positives with Ictotest tablet Serum test for total and direct bilirubin is more informative Other Tests Serum total and direct bilirubin

• More sensitive (4x) tablet version of dipstick assay • Especially useful to confirm dipstick in highly colored urines • 10 drops urine applied to reagent pad • Ictotest tablet placed upon pad • 2 drops water added to tablet • After 30 seconds, evaluate visually • Purple or blue color is positive