Clinical meaning
Urinalysis (UA) is a foundational diagnostic tool consisting of three components: gross/physical examination, chemical dipstick analysis, and microscopic sediment examination. Each component provides distinct clinical information that guides differential diagnosis and management. Physical examination assesses color (normal pale to dark yellow; red/brown suggests hematuria or myoglobinuria; orange with rifampin or phenazopyridine; foamy suggests proteinuria), clarity (turbid suggests pyuria, bacteriuria, or crystalluria), and specific gravity (1.001-1.030; reflects concentrating ability; <1.005 suggests diabetes insipidus or overhydration; >1.025 suggests dehydration; fixed at 1.010 indicates loss of concentrating ability as in chronic kidney disease or acute tubular necrosis). Chemical dipstick analysis includes: pH (normal 4.5-8.0; persistently alkaline suggests UTI with urease-producing organisms like Proteus, renal tubular acidosis, or vegetarian diet; acidic in metabolic acidosis, high-protein diet); protein (normally negative; trace amounts may be positional or exercise-induced; persistent proteinuria >30 mg/dL suggests glomerular disease, diabetic nephropathy, or hypertensive nephrosclerosis — quantify with urine albumin-to-creatinine ratio); glucose (normally negative; positive with blood glucose >180 mg/dL exceeding renal threshold; also positive in pregnancy, Fanconi syndrome, SGLT2 inhibitor use); blood (positive with hematuria, hemoglobinuria, or myoglobinuria — differentiate...