Objectives: a) To find out the normal level of 25 hydroxy vitamin D in healthy individuals b) To look for evidence of vitamin D deficiency in patients with active tuberculosis.
Methods: There were 35 cases of pulmonary and extra-pulmonary tuberculosis and 16 controls, whose clinical characteristics, dietary intake of vitamin D and biochemical characteristics including serum vitamin D levels were compared.
Exclusion criteria: malabsorption, liver or renal disorders, intake of drugs, which can reduce vitamin D levels, HIV infection, diabetes, immunosuppressive treatment, and severe protein energy malnutrition.
Results: There was a statistically significant difference (p < 0.005) in mean vitamin D levels between controls (19.5 ng/ml) and study subjects (10.7 ng/ml). Sixteen patients out of 35 had values well below the lower limit of normal (9 ng/ml). No one in the control group had vitamin D level less than 9 ng/ml. However the mean vitamin D level in the control group was less than the mean value quoted in the literature from the West. Sunlight exposure was adequate in those with deficiency but there was reduced dietary intake of vitamin D.
Conclusions: Serum 25 hydroxy vitamin D levels less than 9 ng/ml indicates deficiency. Vitamin D deficiency exists in patients with tuberculosis and it is possibly a cause rather than effect of the disease; deficiency is due to decreased dietary intake. Vitamin D deficiency can occur without any symptoms. If symptoms are present, it indicates severe deficiency. Serum calcium and phosphorus values do not often predict the existence of deficiency.