Improvement in Bone Density with Calcitriol Substitution for Cholecalciferol in Refractory Osteoporosis induced by Prednisone

Abstract

Introduction/ Purpose: Decline in BMD following prednisone therapy is attributed to osteoporosis. However, osteomalacia due to low 125 OH Vitamin D and resulting hyperparathyroidism may also be contributors. Therefore, administration of 125 OH vitamin D3, Calcitriol on BMD was examined in subjects receiving chronic prednisone therapy and low BMD (T< 2.5) refractory to therapy with bisphosphanate, calcium and vitamin D3, Cholecalciferol. Methods: 21 subjects, ages 45–56 years receiving prednisone ≥3 years with declining BMD despite therapy with Cholecalciferol, CaCO3 and bisphosphanate were divided into 2 groups. Both groups continued Calcium and bisphosphanate. 10 subjects (group 1) received increased dose of Cholecalciferol, 2000 units daily while in 11 subjects (group 2), it was substituted by Calcitriol. Comprehensive metabolic panels (CMP) including serum calcium and alkaline phosphatase as well as 25 OH Vit D and 125 OH Vit D levels were determined every 6 months. BMD was determined at yearly interval. Results: CMP including calcium and phosphorus remained normal in both groups while alkaline phosphatase declined in group 2 alone. Serum 25 OH Vit D levels were subnormal (<20 pg/ml) in both groups and normalized (53 ±6 pg/ml) only in group 2. BMD continued to decline in group1 while improving (p<0.01) in group 2; BMD being significantly greater than group 1 (p<0.01). Conclusion: In subjects receiving chronic prednisone therapy, low BMD is induced by multiple mechanisms: osteomalacia caused by decreased 125 OH Vit D and osteoporosis caused by matrix collagen breakdown, hypogonadism and secondary hyperparathyroidism. Role of osteomalacia is confirmed by rising BMD on substituting active 125 OH vitamin D3, Calcitriol for inactive vitamin D3, Cholecalciferol.