Retinol-Binding Protein, 24 Hour, Urine

Casandra

Casandra Test Code MC30703Version 1 (DRAFT)

Performing Lab

Lab Mayo Clinic LabLab Test ID RB24CPT Code 83883

Retinol-Binding Protein, 24 Hour, Urine

Clinical Use

Use

Measurement of urinary retinol-binding protein (RBP) is useful in assessing proximal renal tubular injury or dysfunction. Under normal conditions, RBP is filtered but reabsorbed by proximal tubular cells; elevated urinary excretion indicates impaired tubular function. Elevated excretion rates can occur with tubular disease, toxicity (e.g., heavy metals or nephrotoxic drugs), or in glomerulopathies with concurrent tubular injury. A 24-hour urine collection is considered the gold standard over spot collections for accurate quantification of RBP excretion. ([mayocliniclabs.com](https://www.mayocliniclabs.com/test-catalog/overview/609449?utm_source=openai))

Special Instructions

Order as a renal diagnostics profile that includes RBP1, RBPCN, and creatinine (CRT24). A 24-hour urine volume (in milliliters) must be provided. No preservative should be used; collect a 5‑mL aliquot after mixing. Transport must occur within 4 hours of collection completion; refrigeration is preferred (ambient and frozen acceptable for up to 7 days). If not ordering electronically, use the Renal Diagnostics Test Request (T830) form. ([mayocliniclabs.com](https://www.mayocliniclabs.com/test-catalog/overview/609449?utm_source=openai))

Limitations

Since the RBPCN portion uses immunonephelometry, turbidity or particulate matter (e.g., cells, crystals) may interfere with measurement; centrifugation of the urine specimen at ambient temperature prior to assay is recommended. ([mayocliniclabs.com](https://www.mayocliniclabs.com/test-catalog/overview/609449?utm_source=openai))

Test Details

New York Approved