Beta Carotene and Thyroid Replacement

"I have read that those people with hypothyroidism (I'm taking 1 mg of Synthroid a day) have a reduced ability to turn beta carotene (from eating carrots, broccoli, cabbage, kale and other cruciferous vegetables) into Vitamin A. Please address this problem in your newsletter." -- KW, Ann Arbor, Michigan

Hypothyroidism of long duration does produce carotenemia, a condition in which there is an accumulation of beta-carotene in the tissues due to its reduced metabolism into vitamin A. The result is a yellow-orange discoloration of the skin, especially the palms and soles. Unlike jaundice, the whites (sclera) of the eyeballs are not yellow. Carotenemia can also be induced by excessive ingestion of beta-carotene-enriched food such as carrots.

Treatment of hypothyroidism with levothyroxine (Levoxyl, Synthroid, Levothroid, Levo-T) results in a return to normal metabolism. Therefore, carotenemia is not a problem once hypothyroidism is treated.

Any theoretical concerns regarding possible vitamin A deficiency in severe hypothyroidism could be addressed by administering a vitamin A-containing multivitamin. Carotenemia itself does not appear to pose any health risks, and is primarily a cosmetic issue.