The effect of anti-tuberculosis chemotherapy on vitamin D and calcium metabolism.

Serum 25-hydroxycholecalciferol (25-(OH)D3), calcium and albumin have been measured in 27 patients undergoing treatment for pulmonary tuberculosis. Patient 25-(OH)D3 was significantly lower than controls pre-treatment. Throughout the period of treatment patient median 25-(OH)D3 remained below 10 ng/ml, significantly lower than levels in matched healthy controls. Patients' median serum levels varied between 35% and 66% of controls' values during treatment, but rapidly rose to equal control values once treatment had been stopped. Patients' serum calcium, corrected for albumin, remained virtually identical with control values throughout treatment. Clinicians should be aware that standard anti-tuberculosis chemotherapy may depress Vitamin D stores and that this may be important for patients who are already at risk from osteomalacia.