Laboratory Test Reference Guide

Protect from light

Carotenaemia is a harmless condition causing yellow discoloration of skin due to an excess of beta carotene.  Levels are usually between 4.5 and 9 umol/L

Beta carotene is secreted by sebaceous glands and probably sweat, areas with high sweat production (e.g. palms, nasolabial folds) are most affected. Sclera and mucosal surfaces are not affected.

Beta carotene is present in a long list of fruits and vegetables. Chlorophyll masks the presence of beta carotene in green vegetables.

Mashing, cooking and pureeing of food break cell membranes, which results in increased absorption of beta carotene.

Lycopene is an isomer of beta carotene but is not converted to Vitamin A, present in tomatoes and can cause “orange “ skin.

Absorption of  beta carotene is highly variable. 

Beta carotene is converted enzymatically in the small intestine to Vitamin A. With high beta carotene intake the conversion is rate limited (and toxicity does not occur).

Beta carotene is transported by beta lipoproteins, levels increase in parallel to an increase in non HDL cholesterol

Causes

High beta carotene intake – commonest cause

Hypothyroidism – increase in beta lipoproteins and reduced enzymatic conversion to Vitamin A

Diabetes and Nephrotic syndrome  - increase in beta lipoproteins

Anorexia nervosa - increase in beta lipoproteins, reduced enzymatic conversion to Vitamin A and an increase in intake of low calorie food rich in beta carotene

Liver disease - reduced enzymatic conversion to Vitamin A

Familial - reduced enzymatic conversion to Vitamin A. (Vitamin A absorption is not affected – probably harmless, little information available)

Samples not protected from light will require a recollect.

CHL

https://www.chl.co.nz/test/carotene-plasma-plasma-serum/