14 August 2018

This article is published in the Asia Pac J Clin Nutr 2017;26(3):412-420 

Section: Original Article

Authors: Yogeswari Venugopal MBBS, MRCP, Sharifah F Wan Muhamad Hatta MBChB, MMed, MRCP, Nurbazlin Musa BSc, Siti Abdul Rahman BSc, Jeyakantha Ratnasingam MD, Mmed, Sharmila Sunita Paramasivam MD, MRCP, Lee Ling Lim MBBS, MRCP, Luqman Ibrahim MBBS, Mmed, Karen Choong MD, Alexander TB Tan MBChB, MRCP, Karuthan Chinna BSc, MSc, PhD, Siew Pheng Chan MBBS, MRCP, Shireene R Vethakkan MBBS, MMed, MD 

Institution: Department of Medicine, University of Malaya, Lembah Pantai, 59100 Kuala Lumpur, Malaysia 


Background and Objectives: Vitamin D3 (cholecalciferol) dose required to maintain sufficiency in non-Caucasian women with postmenopausal osteoporosis (PMO) inthe tropics has not been well studied. Some guidelines mandate 800-1000 IU vitamin D/day but the Endocrine Society (US) advocates 1500-2000 IU/day to maintain 25-hydroxyvitamin-D (25(OH)D) concentration at >75 nmol/L. We aimed to establish oral cholecalciferol dose required to maintain 25(OH)D concentration at >75 nmol/L in PMO Chinese Malaysian women, postulating lower dose requirements amongst light-skinned subjects in the tropics. 

Methods and Study Design: 90 Chinese Malaysian PMO women in Kuala Lumpur, Malaysia (2°30’N) with baseline serum 25(OH)D levels ≥50 nmol/L were recruited. Prior vitamin D supplements were discontinued and subjects randomized to oral cholecalciferol 25,000 IU/4-weekly (Group-A) or 50,000 IU/4-weekly (Group- B) for 16 weeks, administered under direct observation. Serum 25(OH)D, PTH, serum/urinary calcium were measured at baseline, 8 and 16 weeks.

Results: Baseline characteristics, including osteoporosis severity, sun exposure (~3 hours/week), and serum 25(OH)D did not differ between treatment arms. After 16 weeks, 91% of women sufficient at baseline, remained sufficient on 25,000 IU/4-weekly compared with 97% on 50,000 IU/4-weekly with mean serum 25(OH)D 108.1±20.4 and 114.7±18.4 SD nmol/L respectively (p=0.273). At trial’s end, 39% and 80% of insufficient women at baseline attained sufficiency in Group A and Group B (p=0.057). Neither dose was associated with hyperparathyroidism or toxicity.

Conclusions: Despite pretrial vitamin D supplementation and adequate sun exposure, 25.6% Chinese Malaysian PMO women were vitamin D insufficient indicating sunshine alone cannot ensure sufficiency in the tropics. Both ~900 IU/day and ~1800 IU/day cholecalciferol can safely maintain vitamin D sufficiency in >90% of Chinese Malaysian PMO women. Higher doses are required with baseline concentration <75 nmol/L.

Keywords: vitamin D, oral cholecalciferol, postmenopausal osteoporosis, Chinese ethnicity, tropical 

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