title: Prolonged treatment with vitamin D in postmenopausal women with primary hyperparathyroidism.
abstract: BACKGROUND
  Vitamin D deficiency further increases circulating parathyroid hormone (PTH) levels in patients with primary hyperparathyroidism (pHPT), with potential detrimental effects on bone mass.
  
  
  METHODS
  This was an observational clinical study in consecutive conservatively treated postmenopausal women (n=40) with pHPT and coexistent 25-hydroxyvitamin D deficiency (25OHD ≤50 nmol/l (≤20 ng/ml)). Patients who showed an increase in serum 25OHD above the threshold of vitamin D deficiency (>50 nmol/l; n=28) using treatment with various commonly prescribed vitamin D preparations were, for the purposes of statistical analyses, allocated to the treatment group. Patients who were retrospectively identified as having received no treatment with vitamin D and/or remained vitamin D deficient were considered as non-responders/controls (n=12). Adjusted calcium (adjCa), PTH and 25OHD concentrations were monitored in all subjects up to 54 months (mean observation period of 18±2 months).
  
  
  RESULTS
  Prolonged increased vitamin D intake, regardless of the source (serum 25OHD, increase from 32.2±1.7 nmol/l at baseline to 136.4±11.6 nmol/l, P<0.0001), significantly reduced serum PTH (13.3±1.1 vs 10.5±1.0 pmol/l, P=0.0001), with no adverse effects on adjCa levels (2.60±0.03 vs 2.60±0.02 mmol/l, P=0.77) and renal function tests (P>0.73). In contrast, serum PTH remained unchanged (15.8±2.6 vs 16.3±1.9 pmol/l, P=0.64) in patients who remained vitamin D deficient, with a significant difference between groups in changes of PTH (P=0.0003). Intrapartial correlation analyses showed an independent negative correlation of changes in 25OHD with PTH levels (r ic=-0.41, P=0.014).
  
  
  CONCLUSIONS
  Prolonged treatment with vitamin D in various commonly prescribed preparations appeared to be safe and significantly reduced PTH levels by 21%.
authors.affiliation: Warwickshire Institute for the Study of Diabetes, Endocrinology and Metabolism University Hospitals Coventry and Warwickshire NHS Trust Coventry UK.
authors.forename: Ranganathan R
authors.initials: RR
authors.lastname: Rao
authors.forename: Harpal S
authors.initials: HS
authors.lastname: Randeva
authors.forename: Sailesh
authors.initials: S
authors.lastname: Sankaranarayanan
authors.forename: Murthy
authors.initials: M
authors.lastname: Narashima
authors.forename: Matthias
authors.initials: M
authors.lastname: Möhlig
authors.forename: Hisham
authors.initials: H
authors.lastname: Mehanna
authors.forename: Martin O
authors.initials: MO
authors.lastname: Weickert
keywords: bone; calcium; hormone action; parathyroids