Primary hyperparathyroidism and severe hypercalcemia with low circulating 1,25-dihydroxyvitamin D

J Clin Endocrinol Metab. 1990 Nov;71(5):1305-9. doi: 10.1210/jcem-71-5-1305.


We report a postmenopausal woman with primary hyperparathyroidism (PHPT) and severe hypercalcemia while her total calcium intake was more than 2 g daily. Despite a markedly elevated intact PTH level, her serum 1,25-dihydroxyvitamin D [1,25-(OH)2D] level was low (17 pmol/L; 7 pg/mL). With reduced calcium intake, her serum calcium normalized, and 1,25-(OH)2D increased to 122 pmol/L (51 pg/mL). At the same time, intact PTH decreased to 32% of the initial value. PHPT may be associated with low circulating 1,25-(OH)2D levels. Furthermore, low 1,25-(OH)2D levels in PHPT may be due to a direct effect of severe hypercalcemia and be reversible with correction of hypercalcemia.

Publication types

  • Case Reports

MeSH terms

  • Aged
  • Calcitriol / blood*
  • Calcium / blood
  • Calcium, Dietary / analysis
  • Female
  • Humans
  • Hypercalcemia / blood*
  • Hypercalcemia / complications
  • Hyperparathyroidism / blood*
  • Hyperparathyroidism / complications
  • Parathyroid Hormone / blood


  • Calcium, Dietary
  • Parathyroid Hormone
  • Calcitriol
  • Calcium