Vitamin D deficiency in hyperthyroidism

Sir,

I read the aricle by Jyotsana et al1 with interest in which authors have described bone mineral homeostasis in subjects with hyperthyroidism1. The most surprising element is lower vitamin D levels in controls compared to patients. Authors have failed to give adequate explanation of this finding. We have reported significantly lower vitamin D levels in Indian patients with hyperthyroidism2. In this study, 30 patients with thyrotoxicosis were studied for vitamin D status and bone mineral density (BMD). The mean 25 (OH) vitamin D levels in patient group were 15.3±7.1 ng/ml and 30 per cent of patients had severe vitamin D deficiency (<10 ng/ml). We have postulated hyperpigmentation of skin, malabsorption and increased vitamin D metabolism as possible mechanisms of vitamin D deficiency in hyperthyroidism3. Authors of the present study1 have not cited this important paper which was first reported study on this subject from India. Goswami et al4 have reported malabsorption in Indian patients with hyperthyroidism. According to this study significant number of patients (46%) with thyrotoxicosis in India had fat mal- absorption4. Absorption of fat soluble vitamins such as vitamin D is likely to be hindered in such a state. It is worthwhile to study correlation between steatorrhea and vitamin D status in these patients with thyrotoxicosis. Also, in Table I mean age in two groups looks similar but has been shown as significantly different. The signs ^* and ^** have not been explained.