To the Editor.
—In a recent issue of the Archives (134:674-678, 1974) a statement is made regarding the cause for the myopathy seen in hypophosphatemia. The authors say, "The question whether hypophosphatemia might contribute to the myopathy of hyperparathyroidism seems not to have been previously discussed."We had the opportunity to study a patient with severe hypophosphatemic osteomalacia in the Clinical Center of the National Institutes of Health.1 In that patient, because of his myopathy, we decided to measure the adenosine triphosphate, creatine phosphate, inorganic phosphate, and total creatinine levels from a section of intercostal muscle that was frozen immediately after removal with isopenthane cooled with liquid nitrogen. The values found were within the normal range.Since those results were obtained at a time when the serum phosphorus value was 1.2 mg/100 ml, we stated in our discussion, "It appears unlikely that a decrease of available high-energy phosphate