Laboratory Tests for Lower Urinary Tract Symptoms (LUTS)
Mandatory Initial Laboratory Tests
Order urinalysis and serum PSA (with shared decision-making) as the core laboratory evaluation for men presenting with LUTS. 1, 2
Urinalysis (Required for All Patients)
- Perform urinalysis using dipstick testing to screen for hematuria, pyuria, proteinuria, glucosuria, ketonuria, and positive nitrite test. 1, 2
- Order urine microscopy and culture if the dipstick shows any abnormalities (hematuria, pyuria, proteinuria, or positive nitrite). 1
- This test excludes bladder cancer, carcinoma in situ, urinary tract infections, urethral strictures, distal urethral stones, and bladder stones—all of which can mimic BPH symptoms. 1
Serum PSA (Conditional—Requires Shared Decision-Making)
Only order PSA if the patient has >10 years life expectancy AND either: 1, 3
- A prostate cancer diagnosis would change management, OR
- The PSA result would influence treatment decisions for LUTS (since PSA predicts prostate volume and risk of symptom progression)
Before ordering PSA, you must discuss with the patient: 1, 3
- Risk of false-positive results (approximately 25% of men with BPH have PSA >4 ng/mL) 1
- Risk of false-negative results 3
- Potential complications of subsequent transrectal ultrasound-guided biopsy (infection, bleeding, pain) 1, 3
- Possibility of false-negative biopsy results 1
Clinical utility of PSA in LUTS: 1, 3
- PSA reasonably predicts prostate volume for treatment planning 1, 3
- Higher PSA levels predict increased risk of prostate growth, symptom deterioration, acute urinary retention, and need for BPH-related surgery 1
Laboratory Tests NOT Routinely Recommended
Serum Creatinine (Not Routine)
Do not order serum creatinine routinely in the initial evaluation of uncomplicated LUTS. 1
Only order renal function tests if: 2
- Renal impairment is suspected from history and clinical examination
- Patient has hydronephrosis on imaging
- Considering surgical treatment for LUTS
- Baseline renal insufficiency is no more common in men with BPH than age-matched controls, and renal insufficiency occurs in <1% of BPH patients in large clinical trials 1
Additional Non-Laboratory Assessments (Part of Complete Evaluation)
While not laboratory tests, these assessments are mandatory components of the initial LUTS evaluation:
Symptom Quantification (Required)
- Use validated questionnaires such as International Prostate Symptom Score (I-PSS) with bother score, DAN-PSS, ICIQ-MLUTS, or BPH Impact Index to grade symptom severity and degree of bother. 1, 2, 4
Frequency-Volume Chart (Required for Specific Presentations)
- Order a 3-day voiding diary for patients with predominant nocturia (≥2 voids per night) to distinguish 24-hour polyuria (>3 liters/day) from nocturnal polyuria (>33% of 24-hour output at night). 1, 2
Post-Void Residual (Recommended)
- Measure PVR by bladder ultrasound to assess bladder emptying; this is recommended before treatment decisions. 2, 4
Uroflowmetry (Recommended)
- Perform uroflowmetry before any treatment to objectively measure maximum flow rate. 2
Critical Pitfalls to Avoid
- Do not skip urinalysis—it is mandatory for all patients and may reveal alternative diagnoses requiring different management. 1, 2
- Do not order PSA without shared decision-making—approximately 75% of men with symptomatic BPH have PSA <4 ng/mL, yet still have significant prostatic enlargement. 3
- Do not order routine creatinine—renal insufficiency from BPH is rare (<1%) and routine testing is not cost-effective. 1
- Do not rely on PSA alone for cancer screening—abnormal DRE findings mandate further evaluation regardless of PSA level. 3