Comments on “Hipercarotinemia after bariatric surgery”

Sir,

The article «Hypercarotinemia after bariatric surgery», published by Gutiérrez-Medina, S. et al.,¹ reports the case of a patient with possible hypercarotinemia secondary to vitamin A supplementation after bariatric surgery who attended the emergency room for probable carotenodermia. This case attracted our interest because of the uncommon occurrence of this condition in clinical practice, its unexpected finding in a patient with probable malabsorption after bariatric surgery, and the interpretation and diagnosis based on the parameters reported (“hypercarotinemia secondary to treatment with vitamin A”). In this context, we would like to refer to some points that could contribute to clarify these findings.

First of all, the term «hypercarotinemia» appearing in the title as referring to the diagnosis of the patient does not appear to be adequate, because it refers to an increase in blood carotenoid levels (>300 μg/dL),² and no reference is made in the article to any measurement of carotenoid levels during the follow-up of the patient.

Second, the orange-yellow pigmentation of the skin reported in this patient (possible carotenodermia or palmoplantar xanthosis) is a secondary disorder associated with hypercarotinemia (rather than hypervitaminosis A), although high blood carotenoid levels are not always associated with carotenodermia. This reversible pigmentation is due to the deposition in the horny layer of carotenoids, which become most evident in the soles of the feet, the palms of the hands, the forehead, and the nasolabial folds.³ The cause is, in most cases, due to the excess consumption of carotenoids in the diet or in food supplements, although the deposition may also occur in some diseases (e.g. diabetes mellitus, hypothyroidism, anorexia nervosa). Moreover, in contrast to the usual homogeneous and bilateral (in both hands and legs) presentation of carotenodermia, pigmentation in the reported case showed color to be especially concentrated in the fingers and only appeared on the palm of one hand, which is extremely unusual in the literature.^3–5

Finally, the diagnosis appears to relate palmar pigmentation to hypercarotinemia secondary to hypervitaminosis A, as the patient had symptoms consistent with vitamin A toxicity. Two facts should be mentioned in this regard: (1) blood retinol levels did not exceed the normal range at any time, and were even below the lower limit, i.e. they suggested a deficiency, and high levels of retinyl ester forms (a potential marker of toxicity) were not reported either⁶; and (2) while some carotenoids may be converted into retinol, humans cannot synthesize carotenoids de novo or from retinol.⁷

In the case reported, the carotenodermia seen should be associated with excess blood carotenoids resulting from a high intake and, possibly, a blockade in the conversion to retinol due to vitamin A overdosing. Unfortunately, carotenoid intake was not measured, and excess absorption is unlikely because of the malabsorption derived from bariatric surgery.^8,9 Therefore, because of the lack of information on blood carotenoid levels, and the biochemical criteria suggesting vitamin A toxicity,⁶ the diagnosis should be reconsidered.