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Relationship between Vitamin D, calcium and PTH in Cape Town
  1. David Haarburger (david.haarburger{at}
  1. Groote Schuur Hospital, University of Cape Town, South Africa
    1. Mariza Hoffmann (mariza{at}
    1. Tygerberg Hospital, South Africa
      1. Rajiv Erasmus (rte{at}
      1. University of Stellenbosch, South Africa
        1. Tahir Pillay (profts.pillay{at}
        1. University of Cape Town, South Africa


          Aim: The aim of this study was to test the hypothesis that Vitamin D deficiency is associated with abnormal Calcium and PTH levels.

          Methods: Vitamin D requests at a tertiary hospital in South Africa over 2 years were retrospectively analysed along with calcium and PTH levels.

          Results: Only when 25(OH)D level dropped below 25nmol/l, was there a significant rise in PTH. A subnormal 25(OH)D level was also not always related to hypocalcaemia as more than half of patients with their 25(OH)D level below 25nmol/l had calcium levels in the reference range. However, all patients with calcium levels below 1.8mmol/l were shown to have Vitamin D insufficiency.

          Conclusion: Hypovitaminosis D may co-exist with a blunted PTH response. Therefore, assumptions about vitamin D status should not be made based on PTH and calcium values. 25(OH)D measurements should be requested when vitamin D deficiency is clinically suspected, irrespective of biochemical results.

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