Alfacalcidol versus calcitriol in the management of patient with hypoparathyroidism: a randomized control trial
Abstract Context Alfacalcidol and calcitriol are commonly used for managing hypoparathyroidism. Their relative merits have not been systematically assessed. Objective We compared the effect of alfacalcidol and calcitriol on phosphatemic control, hypercalciuria and associated factors in idiopathic-hypoparathyroidism (IH). Design and Setting Open label randomized-controlled-trial, tertiary-care-center. Subjects and Methods IH patients with optimal calcemic control on alfacalcidol were continued on the same (n=20) or switched to calcitriol (n=25) at half of the ongoing alfacalcidol dose. The dose was adjusted during follow-up to maintain serum total calcium between 8.0-9.5 mg/dL. Serum calcium, phosphorus, 25-hydroxyvitamin-D, 1,25-dihydroxyvitamin-D, 24-hr urine calcium-to-creatinine ratio, fractional-excretion-of-phosphorus (FEPh) were measured at baseline and six-months. Plasma intact-FGF23 was measured at final follow-up. Result Patients receiving alfacalcidol and calcitriol had comparable serum calcium at six-months (8.7 ± 0.4 vs. 8.9 ± 0.4 mg/dL, P = 0.13). Their median (IQR) dose at six-months was 2.0 (1.0-2.5) and 0.75 (0.5-1.0) µg/d, respectively. Serum 1,25(OH)2D levels were physiological in both (35.3 ± 11.6 and 32.3 ± 16.9 pg/ml). Serum phosphate and calcium-excretion were comparable in two arms. Majority had hyperphosphatemia (75% vs. 76%), hypercalciuria (75% vs. 72%) and elevated FGF23 (116 ± 68 and 113 ± 57 pg/mL). Age showed significant independent association with plasma FGF23 (β = 1.9, P = 0.001). Average FEPh was low despite high FGF23. Conclusion At optimal calcium control both alfacalcidol and calcitriol lead to comparable but high serum phosphate levels, hypercalciuria, physiological circulating 1,25(OH)2D and elevated FGF23. Further studies are required to systematically investigate other treatment options.