Low parathyroid hormone levels in bedridden geriatric patients with vitamin D deficiency

J Am Geriatr Soc. 2009 Jun;57(6):1045-50. doi: 10.1111/j.1532-5415.2009.02257.x. Epub 2009 Apr 14.

Abstract

Objectives: 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.

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

Setting: Four long-term care hospitals in Helsinki, Finland.

Participants: Two hundred eighteen chronically bedridden patients.

Measurements: 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.

Conclusion: 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.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Activities of Daily Living
  • Aged, 80 and over
  • Body Mass Index
  • Collagen Type I
  • Double-Blind Method
  • Female
  • Follow-Up Studies
  • Hip Fractures / complications
  • Humans
  • Male
  • Parathyroid Hormone / blood*
  • Peptide Fragments / blood
  • Peptides
  • Procollagen / blood
  • Vitamin D / administration & dosage
  • Vitamin D / analogs & derivatives
  • Vitamin D / blood
  • Vitamin D Deficiency / blood*

Substances

  • Collagen Type I
  • Parathyroid Hormone
  • Peptide Fragments
  • Peptides
  • Procollagen
  • collagen type I trimeric cross-linked peptide
  • procollagen Type I N-terminal peptide
  • Vitamin D
  • 25-hydroxyvitamin D