Low parathyroid hormone levels in bedridden geriatric patients with vitamin D deficiency.
OBJECTIVE
To identify the clinical conditions associated with low parathyroid hormone (PTH) in patients with vitamin D deficiency and to evaluate the stability of the blunted PTH response to vitamin D deficiency over 6 months.


METHODS
Secondary analysis of a randomized double-blind controlled vitamin D supplementation trial.


METHODS
Four long-term care hospitals in Helsinki, Finland.


METHODS
Two hundred eighteen chronically bedridden patients.


METHODS
Plasma 25-hydroxyvitamin D (25-OHD), intact PTH, amino-terminal propeptide of type I procollagen (PINP), carboxy-terminal telopeptide of type I collagen (ICTP), activities of daily living (ADLs), and body mass index (BMI) were measured at baseline and at 6 months. Patient records were reviewed for demographic data.


RESULTS
PTH was within reference values (8-73 ng/L) despite low 25-OHD level (<50 nmol/L) in 74.8% (n=163) of patients (mean age 84.5+/-7.5). Patients in the lowest PTH quartile (<38 ng/L) were characterized by a history of hip fractures (OR=2.9, P=0.01), low BMI (OR=0.9, P=.02), and high ICTP (OR=1.1, P=.03). PTH remained within reference values even after 6 months in 76.2% of the patients with persistent vitamin D deficiency in the placebo group.


CONCLUSIONS
The absence of secondary hyperparathyroidism seems to be common and persistent in frail chronically bedridden patients with vitamin D deficiency. Attenuated parathyroid function appears to be associated with immobilization that causes accelerated bone resorption. Further studies addressing the possible adverse effects of low PTH are warranted.
Björkman
Mikko P
MP
Helsinki University Central Hospital, Clinic of Internal Medicine, POB 340, HUS FI-00029, Helsinki, Finland. mikko.bjorkman@helsinki.fi
Sorva
Antti J
AJ
Risteli
Juha
J
Tilvis
Reijo S
RS
D000203:Activities of Daily Living; D000369:Aged, 80 and over; D015992:Body Mass Index; D024042:Collagen Type I; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D006620:Hip Fractures / Q000150:complications; D006801:Humans; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood*; D010446:Peptide Fragments / Q000097:blood; D010455:Peptides; D011347:Procollagen / Q000097:blood; D014807:Vitamin D / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood*
D024042:Collagen Type I; D010281:Parathyroid Hormone; D010446:Peptide Fragments; D010455:Peptides; D011347:Procollagen; C052929:collagen type I trimeric cross-linked peptide; C047202:procollagen Type I N-terminal peptide; D014807:Vitamin D; C104450:25-hydroxyvitamin D