Progressive Muscle Weakness in Hyperparathyroidism

Background: Progressive muscle weakness without definite etiology is still a diagnostic problem. Hyperparathyroidism is one of the implicated causes of this medical controversy. Objective: This study aims at exploring the role of hyperparathyroidism as a possible cause of unexplained progressive muscle weakness. Methods: Out of 83 patients with progressive muscle weakness screened for parathyroid functions, nine patients proved to have hyperparathyroidism. Patients were evaluated clinically, neurophysiologically and by laboratory assessment ( routine laboratory investigations, and hormonal profile). Muscle biopsy was done in 2 patients. Results: Progressive proximal muscle weakness secondary to hyperparathyroidism was recorded in 9 patients (10.8%), and this weakness is mostly neurogenic with no evidence of myopathic changes. The definite pathophysiologic mechanisms of this weakness is still not clear yet, however, the proposed causes are elevated parathyroid hormone level, hypocalcemia, hypophosphatemia, and decreased vitamin D level. Conclusion: Hyperparathyroidism is a possible treatable cause of progressive muscle weakness, and should be included in the differential diagnosis of patients presenting with unexplained muscle weakness. [Egypt J Neurol Psychiat Neurosurg. 2010; 47(3): 441-445]