—As we have indicated in our article, sequential measurements of serum PTH and 25-OHD suggest that these hormones are not the cause of the hypercalcemia of acute renal failure due to rhabdomyolysis. Other investigators have demonstrated, however, modest elevations in the levels of 25-OHD in this setting,1 although far less than that noted in vitamin D intoxication.2
We agree that levels of other vitamin D metabolites should be measured. Because the 1-hydroxylation of 25-OHD is inhibited by hypercalcemia, decreased levels of PTH, and hyperphosphatemia,3 as verified in our case report, and since glucocorticoid therapy has failed to lower the serum calcium value in this syndrom,4,5 we think that a derangement of vitamin D metabolism is unlikely to explain the hypercalcemia.
Weinstein RS. Hypercalcemia and Vitamin D Metabolism-Reply. Arch Intern Med. 1981;141(8):1102. doi:10.1001/archinte.1981.00340080138036