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Serum or Plasma Retinol Binding Protein Concentration (Mass Concentration)

Published: August 9, 2026Updated: August 16, 2026

This test measures the level of retinol binding protein (RBP) in your blood. RBP helps transport vitamin A, which is important for vision, immune function, and cell growth.

Quick summary

["RBP levels can help assess vitamin A status and related health risks."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
34420-0
Short code
Mid Retics NFr
Synonyms
Mid Retics NFr
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why Might This Test Be Ordered?

Your healthcare provider may order this test if you have symptoms of vitamin A deficiency, such as dry or itchy skin, frequent infections, or vision problems. It may also be used to monitor vitamin A levels in people with certain medical conditions, like kidney disease, or those taking medications that affect vitamin A metabolism.

What Does a Low or High Level Mean?

Low levels of RBP might suggest vitamin A deficiency or kidney problems, as the kidneys usually filter out excess RBP. High levels could indicate liver disease or certain medications that alter protein function.

How Is This Test Done?

A blood sample is taken from a vein, usually in your arm. The blood is then sent to a lab where it is analyzed to measure RBP concentration using a specialized test method.

What Should You Expect Before or After the Test?

No special preparation is usually needed, but you may be asked to avoid certain medications that could affect results. After the blood draw, you may experience mild discomfort, but rest and hydration are generally recommended.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Retinol Binding Protein (RBP)

Frequently asked questions

What causes vitamin A deficiency that might affect RBP levels?
Vitamin A deficiency can result from poor diet (lack of foods like liver, carrots, or sweet potatoes), malabsorption issues (such as celiac disease or Crohn’s), chronic liver disease, or certain medications that interfere with vitamin A absorption or metabolism.
Can kidney disease affect RBP levels?
Yes, kidney disease can cause RBP to build up in the blood because the kidneys normally filter and remove excess RBP. This is why RBP levels are often checked in people with kidney problems to monitor kidney function and vitamin A status.
Are there any foods or supplements that could affect RBP test results?
While RBP itself is a protein, vitamin A levels (which RBP helps transport) can be influenced by dietary intake of vitamin A-rich foods or supplements. However, the test itself measures RBP concentration directly, not vitamin A levels directly, so dietary intake of vitamin A may not directly alter RBP results unless it affects overall protein metabolism.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy