Calcium metabolism in amyotrophic lateral sclerosis.

Calcium metabolism was studied prospectively in 12 patients with amyotrophic lateral sclerosis. Two patients showed mild hypocalcemia, malabsorption of calcium, and elevated plasma parathyroid hormone concentrations. Serum 25-hydroxyvitamin D was decreased in one and low-normal in the second. These two patients and a third showed aminoaciduria on thin layer chromatography. Calcium metabolism was apparently restored to normal by dihydrotachysterol, a vitamin D analog, but no improvement in neurologic function resulted. Bone radiographs taken in search of metabolic bone disease showed a significant increase in the incidence of congenital vertebral anomalies in the ALS patients (50% versus 8%). The relationship of the abnormalities in calcium metabolism and in vertebral structure to the etiology of motor neuron disease is not known.