Influence of vitamin D administration on bone ultrasound measurements in patients on anticonvulsant therapy

BACKGROUND: The objective of the study was to evaluate bone mass status (as measured by bone ultrasound) in patients on anticonvulsant therapy, and the influence that Vitamin D administration exerts over it. MATERIALS AND METHODS: We measured and compared the basal serum levels of 25(OH)D3, parathyroid hormone (PTH), and phalangeal bone ultrasound (Ad-SOS), in 30 adult patients who were taking anticonvulsant drugs, with a control group of similar age and sex. We then gave the patients a large oral dose of 3 mg (120.000 UI) of 25(OH)D3, and repeated the measurements after one month. RESULTS: Basal 25(OH)D3 and Ad-SOS values were significantly lower, and PTH values significantly higher (P< 0.0001 in all), in the patient group. The low Ad-SOS values for the patients were independent of the treatment, but directly related to basal 25(OH)D3 levels (r = 0.45, P<0.01). There was a negative association between PTH and 25(OH)D3 (r = -0.64, P<0.0001), and no correlation between PTH y Ad-SOS (r = -0.20, p NS). After ingestion of the large dose of the vitamin D, the patient group registered a significant (P<0.0001) increase in 25(OH)D3 levels, their Ad-SOS values increased (P<0.0001) nearly to the mean basal value of the control group, and PTH decreased significantly (P<0.0001). CONCLUSIONS: These findings justify the need to assure adequate vitamin D intake in patients being treated with anticonvulsants, independently of the treatment, age, sex, and activity status, in order to prevent osteomalacia.