Leukonychia is divided into 2 major types: true leukonychia, which involves the nail plate, and apparent leukonychia, which involves the nail bed.1 Herein, we present the first case to our knowledge of true leukonychia successfully treated with selenium substitution.
A man in his 30s presented with an 18-year history of Crohn disease and had undergone partial resections of both small and large bowel 6 times. In recent years, the patient had been maintained on total parenteral nutrition, taking enteral nutritional products because of short-bowel syndrome. He was referred to our outpatient clinic with a 2-week history of nail color changes.
On physical examination, we found that the proximal halves of the affected nails of his fingers and toes were whitish; the distal halves were normal; and the 2 color zones were sharply demarcated (Figure, A). Routine laboratory examination for patients on total parenteral nutrition revealed a significantly low serum selenium level (2.0 μg/dL; reference level, 10.6-17.4 μg/dL). After treatment with 100 μg/d of selenium for 8 weeks to improve the selenium deficiency, interestingly, the proximal part of the nails at the nail base gradually turned normal, and the whitish part moved toward the distal direction without changing in appearance or size (Figure, B). Consequently, the whitish part regressed completely, and the nail conditions turned normal in 14 weeks (Figure, C).
A, Leukonychia before selenium substitution manifests as whitish proximal fingernail halves, while the distal halves are normal, and on each nail, the 2 color zones are sharply demarcated. B, After 8 weeks of selenium substitution, the whitish halves of the fingernails have moved toward the distal portions. C, After 14 weeks of selenium substitution, the nail conditions have turned normal.
The present patient presented with true leukonychia in association with Crohn disease as well as selenium deficiency. Although there have been some reports about associations of leukonychia, Crohn disease, and selenium deficiency, all 3 conditions have not been discussed together. An association of Crohn disease with half-and-half nails has been reported in at least 1 case,2 but the serum selenium levels were not estimated in that case. Furthermore, Crohn disease has been associated with selenium deficiency,3 but the nail conditions were not described in detail in those reports. Therefore, we believe this case to be the first providing evidence that true leukonychia is caused in part, if not wholly, by selenium deficiency in Crohn disease and is curable with selenium substitution. However, care must be taken with adverse effects,4 and selenium levels must be carefully monitored to avoid toxic effects.
Leukonychia is caused by the abnormality of either nail bed or nail plate. In half-and-half nails, Lindsay5 has suggested that the whitish part of the nails stayed at the same portion and remained unchanged while the nail grew toward the distal portion, implying that the cause of color change begins in the nail bed rather than the nail plate. On the other hand, our true leukonychia case showed an interesting clinical course during the improvement of nail color in which the whitish part moved toward the distal portion during the nail growth after selenium substitution, suggesting that the primary pathologic site was not in the nail bed but in the nail plate.
In addition, little is known about specific physiological roles of selenium in the formation and/or maintenance of the nail apparatus. Selenium is a component of the antioxidant enzymes such as glutathione peroxidase and thioredoxin reductase as well as 3 deiodinase enzymes, which convert one thyroid hormone to another. Accordingly, it would be interesting to identify the level of selenium inside the nail matrix and to check also the thyroid profile and the activity of the antioxidant enzymes before and after the selenium substitution.6 Further study is needed to elucidate the pathogenic mechanisms of leukonychia due to deficiency of selenium.
Corresponding Author: Naoko Hasunuma, MD, PhD, Department of Community Medicine and Primary Care Development, Akita University School of Medicine, Hondo1-1-1, Akita, Akita, 010-8543 Japan (email@example.com).
Published Online: March 26, 2014. doi:10.1001/jamadermatol.2013.6701.
Conflict of Interest Disclosures: None reported.
Hasunuma N, Umebayashi Y, Manabe M. True Leukonychia in Crohn Disease Induced by Selenium Deficiency. JAMA Dermatol. 2014;150(7):779-780. doi:10.1001/jamadermatol.2013.6701