Age and Ageing Advance Access originally published online on October 25, 2007
Age and Ageing 2008 37(1):25-31; doi:10.1093/ageing/afm141
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Vitamin D supplementation has minor effects on parathyroid hormone and bone turnover markers in vitamin D–deficient bedridden older patients
1 Clinics of Internal Medicine and Geriatrics, Helsinki University Central Hospital, Helsinki, Finland, POB 340, FI-00290 HUS
2 Department of Long-Term Care, Helsinki Health Center, Helsinki, Finland, POB 6600, FI-00099
3 Department of Clinical Chemistry, University of Oulu, Oulu, Finland, POB 5000, FI-90014
Address correspondence to: B. Mikko. Fax: (+35) 894 717 4693. Email: mikko.bjorkman{at}helsinki.fi
Objectives: to evaluate the effects of vitamin D supplementation on parathyroid function and bone turnover in aged, chronically immobile patients.
Design: a randomised double-blind controlled trial.
Subjects: two hundred and eighteen long-term inpatients aged over 65 years.
Intervention: the patients were randomised into treatment groups of I-III, each receiving 0 IU, 400 IU and 1200 IU cholecalciferol per day, respectively. In case of inadequate consumption of dairy products, patients received a daily calcium substitution of 500 mg.
Measurements: plasma concentrations of 25-hydroxyvitamin D (25-OHD), intact parathyroid hormone (PTH), amino-terminal propeptide of type I procollagen (PINP), a marker of bone formation, and carboxy-terminal telopeptide of type I collagen (ICTP), a marker of bone resorption, were measured at baseline and after 6 months.
Results: the patients (age 84.5 years) were chronically bedridden. The baseline 25-OHD was low (23 nmol/l), correlated inversely with PINP, and tended to associate inversely with PTH. The prevalence of vitamin D deficiency (VDD) (25-OHD < 50 nmol/l) was 98% and PTH was elevated in 23% of the patients. Vitamin D supplementation significantly increased 25-OHD concentrations (124% group II, 204% group III) and decreased PTH (–7% group II, –8% group III). PINP tended to decrease, but ICTP tended to increase, and only their ratio decreased significantly. The tendency of ICTP to increase was inconsistent. Changes in 25-OHD correlated inversely with those in PTH and PINP.
Conclusions: vitamin D supplementation has minor effects on PTH and bone turnover in chronically immobilised aged patients with VDD. Further comparative studies and meta-analyses are warranted to elucidate the confounding effects of different mobility levels on the benefits of vitamin D supplementation in patients with differing baseline PTH levels.
Keywords: vitamin D, parathyroid hormone, bone resorption, chronic immobilisation, aged, elderly
Received 12 March 2007; accepted in revised form 1 September 2007.