Motor neuron disease: retrospective study of associated abnormalities.

In a retrospective study of the charts of 39 patients who had motor neuron disease we found that over 50 percent of patients had radiographic abnormalities of bone and over 20 percent had serum calcium concentrations out of the range observed in normal controls. Statistical analysis indicated that, in respect to serum calcium levels, patients who have motor neuron disease are a separate population. These findings, which might reflect a disturbance in bone or calcium metabolism in patients with motor neuron disease, are of interest in view of the known ability of divalent ions other than calcium, such as lead and mercury, to simulate motor neuron disease, and the discovery that patients with proven primary and secondary hyperparathyroidism may have features of amyotrophic lateral sclerosis.