Intestinal calcium absorption in exogenous hypercortisonism. Role of 25-hydroxyvitamin D and corticosteroid dose

J Clin Invest. 1977 Jul;60(1):253-9. doi: 10.1172/JCI108762.


Pharmacologic doses of corticosteroids impair intestinal calcium absorption and contribute to negative calcium balance. However, the relationship between the impaired calcium absorption and a possible defect in the conversion of vitamin D to its physiologically active form, 1,25-dihydroxyvitamin D, is unknown. We compared fractional calcium absorption (double-isotope method, 100-mg carrier) and serum 25-hydroxyvitamin D (25-OH-D) (Haddad method) in 27 patients receiving pharmacologic doses of prednisone with 27 age-, sex-, and season-matched normal subjects. In patients receiving high daily doses of prednisone (15-100 mg/day), calcium absorption (P < 0.02) and serum 25-OH-D (P < 0.001) were decreased. However, in patients receiving low doses (8-10 mg/day) or high doses (30-100 mg) of prednisone on an alternate-day schedule, both of these parameters were normal. Calcium absorption in the patients treated with daily prednisone correlated inversely with the dose of corticosteroids (r = -0.52, P < 0.025) and, in all steroid-treated patients, correlated directly with serum 25-OH-D (r = 0.58, P < 0.01). In four patients who received high-dose corticosteroid therapy for an average of 4 wk, serum 25-OH-D decreased by 35.5% from pretreatment values. Administration of a physiologic or near-physiologic dose of synthetic 1,25-dihydroxyvitamin D(3) (0.4 mug daily for 7 days) to patients receiving high-dose corticosteroids led to an increase in calcium absorption in all patients. These results suggest that calcium malabsorption in the corticosteroid-treated patients is due to a dose-related abnormality of vitamin D metabolism and not to a direct effect of corticosteroids on depressing transmucosal intestinal absorption of calcium.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adrenocortical Hyperfunction / metabolism*
  • Adult
  • Alkaline Phosphatase / blood
  • Calcium / metabolism*
  • Calcium, Dietary
  • Dihydroxycholecalciferols / pharmacology*
  • Dose-Response Relationship, Drug
  • Female
  • Humans
  • Hydroxycholecalciferols / blood*
  • Hydroxycholecalciferols / pharmacology*
  • Intestinal Absorption / drug effects
  • Intestinal Mucosa / physiology
  • Magnesium / blood
  • Male
  • Middle Aged
  • Phosphorus / blood
  • Prednisone / pharmacology*
  • Time Factors
  • Vitamin D


  • Calcium, Dietary
  • Dihydroxycholecalciferols
  • Hydroxycholecalciferols
  • Vitamin D
  • Phosphorus
  • Alkaline Phosphatase
  • Magnesium
  • Calcium
  • Prednisone