Carotene, β

Serum, protected from light

0.7 mL

0.4 mL (Note: This volume does not allow for repeat testing.)

Red-top tube or gel-barrier tube; amber plastic transport tube with amber top. (If amber tubes are unavailable, cover standard transport tube completely, top and bottom, with aluminum foil. Identify specimen with patient's name directly on the container and on the outside of the aluminum foil. Secure with tape.) For amber plastic transport tube and amber-top, order LabCorp N° 23598.

Patient should fast for 12 hours and abstain from alcohol for 24 hours prior to collection. For those who are younger than six months, draw prior to next feeding. Blood should be collected before breakfast in the morning and prior to any medication.

Confirm the diagnosis of carotenoderma; detect fat malabsorption; depressed carotene levels may be found in cases of steatorrhea.

High levels are useful to rule out steatorrhea but lower values lack specificity. There is poor sensitivity. High in the serum of those ingesting large amounts of vegetables. The gold standard for confirmation of a diagnosis of malabsorption remains fat measurement of a 72-hour stool specimen.

High-pressure liquid chromatography (HPLC)

3−91 μg/dL

Vitamin A serum levels do not correlate well with liver stores. Carotenemia may be confused with jaundice. It is also reported high with some cases of diabetes mellitus, myxedema, chronic nephritis, nephrotic syndrome,^1,2 liver disease, hypothyroidism, type I, IIA, and IIB hyperlipoproteinemia, and in a group of amenorrheic hypogonadotropic women.¹ An inverse relationship between serum β-carotene and the risk of bronchogenic squamous cell carcinoma is reported.³ The highest carotene levels are found in the serum of faddists ingesting large amounts of vegetables.⁴ Oral leukoplakia responds well to β-carotene therapy.⁵ Low β-carotene levels are associated with oral contraceptives and smoking.⁶