Children with hemoglobin E/β-thalassemia have a high risk of being vitamin D deficient even if they get abundant sun exposure: a study from Thailand.

BACKGROUND

Vitamin D is a key component in calcium homeostasis, bone mineralization and immune function, and people with a vitamin D deficiency may therefore be at higher risk of osteoporosis, osteopenia, delayed growth and fractures. Vitamin D deficiency is a known clinical complication of patients with β-thalassemia major; however, as yet there are limited data on the vitamin D status of patients with Hb E/β-thalassemia. Hb E/β-thalassemia is characterized by a wide clinical heterogeneity ranging from non-transfusion dependency to transfusion dependency. Because patients with Hb E/β-thalassemia are so clinically diverse, the prevalence of vitamin D deficiency might differ among Hb E/β-thalassemia patients.

PROCEDURE

We investigated the vitamin D status of 109 children with Hb E/β-thalassemia who attended the Pediatric Hematology Clinic at the Siriraj Hospital in Bangkok, Thailand, from April 2009 to March 2010.

RESULTS

Forty-nine of the children were classified as transfusion-dependent (TD) and the remainder (n = 60) as non-transfusion-dependent (NTD). Only 10.1% of the children in our study had normal vitamin D levels, despite Thailand's geographic position 15° N and 100° E and climate, which provides abundant sunlight exposure and therefore efficient vitamin D synthesis. In addition, NTD children were significantly more likely to be vitamin D deficient than TD children (P = 0.01).

CONCLUSIONS

Our results highlight the importance of monitoring serum vitamin D levels in children with Hb E/β-thalassemia regardless of their clinical severity or the amount of sunlight they are exposed to.