Patrick Yao, M.D.
A 22-year-old male presented with yellowish skin discoloration for the past several months. He was concerned about a potential liver problem. He comes from a family of obese parents, and has a constant concern about gaining weight. He enforces a strict low calorie diet of 1200 kcal per day. Despite his weight of 140 lbs and a height of 5 feet 9 inches, he feels that he is grossly over-weight. He also has been feeling depressed. He denies any self-induced purging and binge eating. He denies any alcohol consumption or history of hepatitis. A sample of his daily meal plan reveals a diet high in carrot, spinach, and green beans.
The physical examination revealed yellow-orange discoloration involving primarily the skin of his palms and soles. His mucosal membranes and sclerae were anicteric. No hepatosplenomegaly or thyromegaly was appreciated. A complete blood count, glucose, lipid panel, liver enzymes, and TSH were within normal limits. Nutritional markers including total protein and albumin were normal. His serum carotene level was found to be high at 531 mg/dl (reference range 48-200 mg/dl).
The patient was instructed to eat less foods rich in carotene. He was also referred to eating disorder therapy and community support group. He made the appropriate changes in his diet and the skin discoloration gradually resolved.
Carotenemia, also known as carotenodermia, is defined by an elevated blood level of carotene as a result of the excessive ingestion of dietary precursors to vitamin A. The condition was first described in relation to diet by Hess and Meyers1 in 1919. The high accumulation of carotene in the body leads to an abnormal yellow-orange hue of the skin, particularly in the ears, the palms, and the soles. This symptom is also referred to as xanthosis cutis.
Humans are not able to synthesize carotene; therefore, it is derived from the diet in the form of fruits and vegetables. As a precursor for vitamin A, carotene is converted in the body to retinol, which is one the most active forms of vitamin A. As a lipochrome, carotene contributes to the yellow component of normal skin.2 Excess blood carotene level is most prominent in areas of thickened horny layer such as the palms and soles.3
The most common dietary source of carotene is yellow- or orange-colored foods such as oranges, carrots, squash, and sweet potatoes. Carotene is also found in green-colored vegetables such as green beans, broccoli, spinach, and kale, where the yellow color of carotene is masked by the green color of chlorophyll. Corn is the only commonly used cereal that contains carotene. Dairy products such as butter, eggs, and milk also contain carotene. Lastly, there are also reported cases of carotenemia associated with ingestion of excessive amounts of carotene-rich supplements.4 Carotenemia may be observed 4 to 7 weeks after initiation of a diet rich in carotenoids.
Certain diseases such as hyperlipidemia, diabetes mellitus, and hypothyroidism have been associated with carotenemia. It is thought that the conversion of carotene to vitamin A is impaired in these conditions.5 There have been reports of congenital causes of carotenemia due to an inborn metabolic error or by hepatic disease.6
The association of carotenemia and anorexia nervosa was first described in a case report by Dally7 in 1958. It has been noted more commonly seen in young women drastically reducing their weight and eating foodstuffs with a high carotene conent.8 The exact mechanism by which carotenemia occurs in these patients remains unclear. It is thought that high blood levels of carotene can be induced by unusual feeding habits as seen in patients anorexia nervosa.9 It may also be attributed to an acquired defect in the metabo-lism or utilization of vitamin A in these patients.10 The high serum carotene content can differentiate anorexia nervosa from other forms of malnutrition and weight loss in which the mean serum levels of B-carotene and retinyl esters are decreased.10
It is important to consider hyperbilirubinemia as the main differential diagnosis of carotenemia. The major difference between the jaundice and xanthosis cutis lies in the coloration pattern. In carotenemia, there is a notable absence of discoloration in areas lacking stratum corneum such as the conjunctivae and the oral mucosa. Furthermore, carotenemia is other-wise asymptomatic as opposed to various potential symptoms associated with underlying liver diseases. Other differential to consider include lycopenemia, in which there is an excessive presence of lycopene. As a plant pigment similar to carotene and commonly found in tomatoes, lycopene can also cause a deep yellow-orange pigmentation of the skin.
Other than the cosmetic effect, carotenemia is a rela-tively benign condition. In contrast to vitamin A, an excessive ingestion of beta-carotene does not lead to toxicity because the degree of conversion of carotenes to retinol is not sufficient to cause toxicity. Therapy is based on dietary modification by reducing the carotene consumption. It may take several months before the skin color normalizes. Because caroten-emia can be a sign of other underlying disorders, the physician must investigate the possibility of concomi-tant illnesses.
Submitted on May 30, 2007