Retinol binding protein

ChemistryAlso known as: RBPAlso known as: Retinol-binding proteinmg/dL

Measures the liver protein that transports vitamin A in the bloodstream.

Normal Range
2.6 – 7.6 mg/dL
mg/dL
Abnormal Levels
< 1.5 mg/dL
> 6.7 mg/dL
Specimen Type
Blood

Why This Biomarker Matters

RBP indicates vitamin A nutritional status and liver-kidney function. Abnormal levels can reveal vitamin A deficiency, malabsorption, or organ disease requiring further evaluation.

Understanding Your Results

Normal Range

2.6 – 7.6 mg/dL

Optimal Ranges

Clinician-defined 4-point reference thresholds (mg/dL)

Default Range

1.5
1.5
6.7
6.7
Low
1.5 mg/dL
Borderline Low
1.5 mg/dL
Optimal
6.7 mg/dL
Borderline High
6.7 mg/dL

Overview

Retinol binding protein (RBP) is produced by the liver and transports vitamin A (retinol) through the bloodstream to tissues. An RBP test measures this protein in blood to assess vitamin A status and liver function. Low RBP suggests vitamin A deficiency, malabsorption, or liver dysfunction. Elevated RBP may indicate kidney disease (as kidneys filter RBP) or liver disease. Since RBP reflects both vitamin A status and liver health, abnormal levels warrant further investigation. This test is useful for evaluating nutritional status, assessing causes of vision problems, and screening for organ dysfunction.

Technical Information (LOINC Codes)

Standardized laboratory codes for this biomarker

1836-6Primary
Retinol binding protein [Mass/volume] in Serum or Plasma
mg/dL
18362-4
Retinol binding protein [Mass/time] in 24 hour Urine
mg/(24.h)
33782-4
Retinol binding protein [Mass/volume] in Urine
mg/L
96406-4
Retinol binding protein [Mass/volume] in 24 hour Urine
ug/L

Available Lab Tests

Order tests that measure this biomarker

Retinol Binding Protein

$198.94
Results in 1-3 business days