Urinalysis
Formal Definition
A multi-component urine test evaluating physical properties (color, clarity, specific gravity), chemical dipstick analysis (glucose, protein, blood, leukocyte esterase, nitrites, ketones, bilirubin), and microscopic examination (RBCs, WBCs, casts, bacteria); the first-line test for urinary tract infections, renal disease, and metabolic disorders.
How It's Used on the Ward
"UA" — as in "send a UA and urine culture" — the reflexive urological workup ordered on virtually every admission.
Example
""UA shows leukocyte esterase 3+, nitrites positive, >50 WBCs/hpf, and bacteria on microscopy. Clinical symptoms of dysuria and frequency: treating for uncomplicated UTI. Urine culture pending for sensitivities.""
Clinical Context
Dipstick: leukocyte esterase (proxy for pyuria) and nitrites (gram-negative bacteria convert urinary nitrate to nitrite) are the key UTI markers. Both positive: high specificity for UTI. Microscopy: pyuria defined as >5 WBC/hpf. Bacteriuria without pyuria in asymptomatic patients = asymptomatic bacteriuria (ABU) — do NOT treat in non-pregnant adults or non-urological surgery patients (overly treated ABU drives resistance). RBC casts = glomerulonephritis (nephritic syndrome). WBC casts = pyelonephritis or interstitial nephritis. Waxy casts = advanced chronic kidney disease. Granular/muddy-brown casts = acute tubular necrosis (ATN). Proteinuria: spot urine protein:creatinine ratio >0.3 = significant proteinuria.
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