title: Parathyroid Glands response to Low Vitamin D levels in Healthy Adults: A Cross-Sectional Study.
abstract: OBJECTIVE
  To assess the correlation of serum parathyroid hormone (PTH) and vitamin D (25-OHD) levels based on different assays for measuring 25-OHD in healthy Saudi Arabians living along the east coast.
  
  
  METHODS
  A cross-sectional study was conducted in 200 patients (150 women and 50 men aged between 18-69 years) between January 2011 and December 2012, attending outpatient clinic at King Fahd Hospital of the University, Al Khobar. The first 200 patients seen without vitamin D supplementation at clinic were enrolled in the study. Serum calcium, phosphorous, alkaline phosphatase, parathormone, and 25-OHD tests were performed. 25-OHD was assessed using:chemiluminescence immunoassay (CLIA)radioimmunoassay (RIA) using Wallac 1470 Gamma CounterHPLC -LC.MS (high performance liquid chromatography-liquid chromatography with mass spectrometry. The data was collected, entered into a database and analysed using SPSS, Inc., version 14.
  
  
  RESULTS
  The mean age was 45.8±15.8 (18-74) years, and calcium level was 2.27±0.15 mmol/l. (range 2.125 to 2.62 mmol/l). Alkaline phosphatase was 88.91±35.94 (34-302) IU, parathormone 6.7±3.06 (1.35-21.2) (1.3-6.8 pmol/l). Of the participants, 188 were either vitamin D insufficient or deficient as measured by CLIA 11.85±6.14 (2-29.6), and 91 (48.4%) of them had secondary hyperparathyroidism 9.48±4.55 pc/l. Those with normal CLIA-measured 25-OHD levels had normal PTH levels. Of those with insufficiency, 4/21 (19%) had raised PTH levels; and of those with deficiency, 81/166 (48.79%) had raised levels, whereas with HPLC-LC.MS, 156 were shown to be insufficient and 97 deficient (with PTH level of 7.41±4.2). Thirteen of 41 patients (31.7%) with insufficiency were shown, by HPLC-LC.MS, to have raised PTH. All patients with vitamin D deficiency as diagnosed by HPLC-LC.MS had secondary hyperparathyroidism.
  
  
  CONCLUSIONS
  The above results suggest that the method of measurement strongly influences vitamin D levels and that previous reports suggesting no association between vitamin D deficiency and secondary hyperparathyroidism should be viewed with caution.
authors.affiliation: The Department of Orthopaedic Surgery, College of Medicine, University of Dammam and King Fahd Hospital University AlKhobar, Saudi Arabia.
authors.forename: Mir
authors.initials: M
authors.lastname: Sadat-Ali
authors.affiliation: The Department of Orthopaedic Surgery, College of Medicine, University of Dammam and King Fahd Hospital University AlKhobar, Saudi Arabia.
authors.forename: Abdullah S
authors.initials: AS
authors.lastname: Al-Omran
authors.affiliation: The Department of Obstetrics and Gynecology, College of Medicine, University of Dammam and King Fahd Hospital University AlKhobar, Saudi Arabia.
authors.forename: Haifa A
authors.initials: HA
authors.lastname: Al-Turki
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000469:Alkaline Phosphatase / Q000097:blood; D002118:Calcium / Q000097:blood; D003430:Cross-Sectional Studies; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000097:blood; D008297:Male; D008875:Middle Aged; D010280:Parathyroid Glands / Q000503:physiopathology*; D010281:Parathyroid Hormone / Q000097:blood*; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000503:physiopathology*; D055815:Young Adult
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D; C104450:25-hydroxyvitamin D; D000469:Alkaline Phosphatase; D002118:Calcium