When is a urine analysis indicated?

When is Urinalysis Indicated?

Urinalysis should be performed at initial HIV diagnosis, in all patients with suspected infection (particularly urinary tract or kidney-related), when evaluating microscopic hematuria, for screening high-risk populations annually, and when acute kidney injury or deterioration in known chronic kidney disease is suspected.

Initial Screening and Diagnosis

HIV-Infected Patients

• All patients at the time of HIV diagnosis should undergo screening urinalysis for proteinuria and calculated renal function 1
• Annual follow-up urinalysis is recommended for high-risk groups including African American persons, patients with diabetes, hypertension, hepatitis C coinfection, HIV RNA levels ≥14,000 copies/mL, or CD4+ counts <200 cells/mL 1

Multiple Myeloma Evaluation

• Urinalysis is part of initial diagnostic workup, including 24-hour urine for total protein, urine protein electrophoresis, and urine immunofixation electrophoresis 1
• This helps quantify M-protein components and track disease progression 1

Suspected Infection

Urinary Tract Infections

• Urinalysis should be reserved for patients with acute onset of UTI-associated symptoms (fever, dysuria, gross hematuria, new or worsening urinary incontinence) 1
• Urinalysis and urine cultures should NOT be performed for asymptomatic residents, particularly in long-term care facilities where asymptomatic bacteriuria prevalence is 15-50% 1
• Minimum evaluation should include dipstick for leukocyte esterase and nitrite, plus microscopic examination for WBCs 1
• Only order urine culture if pyuria (≥10 WBCs/high-power field) or positive leukocyte esterase/nitrite is present 1

Fever in Long-Term Care Facilities

• Urinalysis should be performed when residents develop acute UTI-associated symptoms and signs, not routinely for fever alone 1
• If urosepsis is suspected, obtain urine and paired blood specimens for culture and Gram stain of uncentrifuged urine 1

Hematuria Evaluation

Microscopic Hematuria

• Complete urologic evaluation including urinalysis is indicated for all patients with asymptomatic microscopic hematuria 1
• Voided urinary cytology is recommended for all patients with risk factors for transitional cell carcinoma 1
• If initial urinalysis suggests benign cause (menstruation, vigorous exercise, sexual activity, trauma), repeat urinalysis 48 hours after cessation of activity 1
• Comprehensive urine sediment examination should assess for dysmorphic red blood cells (>80% suggests glomerular bleeding) and red cell casts 1

Proteinuria Detection

• If proteinuria grade 1+ is present (≥30 mg/dL or protein-to-creatinine ratio ≥1300 mg/g), quantify using spot urine albumin-to-creatinine or protein-to-creatinine ratios 1
• Persistent proteinuria >1,000 mg/24 hours warrants nephrology referral 2

Acute Kidney Injury

Known CKD with Acute Deterioration

• Perform urine microscopy with sediment analysis immediately when serum creatinine rises >0.3 mg/dL within 48 hours or >50% increase from baseline in known CKD patients 2
• Active sediment (cellular elements, casts) indicates acute-on-chronic kidney disease requiring urgent evaluation and often nephrology referral 2
• Urine sediment analysis is critical when clinical suspicion exists for glomerulonephritis (new hematuria, edema, hypertension) or systemic symptoms suggesting vasculitis or autoimmune disease 2

Differential Diagnosis of AKI

• Urine sediment analysis should be performed routinely in all patients with AKI for differential diagnosis, particularly when glomerular disease is suspected 3
• Fractional excretion of sodium (FENa) helps differentiate prerenal (<1%) from intrinsic AKI (>1%), though its value is limited in sepsis 3
• Structural kidney injury markers (proteinuria >500 mg/day, microhematuria >50 RBCs/hpf) exclude hepatorenal syndrome-AKI diagnosis 3

Medication Monitoring

Trimethoprim-Sulfamethoxazole Therapy

• Urinalyses with careful microscopic examination and renal function tests should be performed during therapy, particularly for patients with impaired renal function 4
• Adequate fluid intake must be ensured to prevent crystalluria and stone formation 4

Chronic Opioid Therapy

• Urine drug testing should be performed before starting opioid therapy for chronic pain and at least annually thereafter 1
• Testing assesses for prescribed medications, other controlled prescription drugs, and illicit drugs 1

Important Caveats

When NOT to Perform Urinalysis

• Do not rely on dipstick urinalysis alone in CKD patients—it lacks sensitivity for detecting cellular elements and casts that define active sediment 2
• Urinalysis is less helpful when CKD cause is well-established (e.g., diabetic nephropathy with typical progression) and no acute change has occurred 2
• Avoid screening asymptomatic patients in long-term care facilities due to high prevalence of asymptomatic bacteriuria 1

Specimen Handling

• Urine is unstable and changes begin immediately after voiding—examine within 2 hours of collection 5, 6
• Midstream clean collection is acceptable in most situations 5
• Catheterized specimen may be required if clean-catch cannot be reliably obtained (vaginal contamination, obesity, phimosis) 1

Integration with Other Tests

• Combine urinalysis with quantitative proteinuria assessment (albumin-to-creatinine or protein-to-creatinine ratio) and serial eGFR measurements for comprehensive evaluation 2
• Renal ultrasound should complement urinalysis to assess kidney size and exclude obstruction when evaluating AKI or CKD 2, 3
• Complete blood count with differential should be performed alongside urinalysis when infection is suspected 1