title: Malabsorption of calcium in corticosteroid-induced osteoporosis.
abstract: We have examined the relation between radiocalcium absorption and serum 1,25-dihydroxyvitamin D [1,25(OH)2D3] levels in a set of 60 postmenopausal women on corticosteroid therapy (29 with and 31 without vertebral compression fractures) and compared these results with those from 31 normal postmenopausal women age-matched with the "normal" corticosteroid-treated women. Radiocalcium absorption was a function of serum 1,25(OH)2D3 in both corticosteroid-treated groups and in the set as a whole, but the impaired calcium absorption in the corticosteroid-treated patients with osteoporosis was not accounted for by their slightly reduced serum 1,25(OH)2D3 levels. This apparent resistance to the intestinal action of 1,25(OH)2D3 was quantified by a Z score which expresses, in standard deviation units, the difference between the measured calcium absorption and that predicted from the 1,25(OH)2D3 level. The Z score was significantly reduced in the osteoporotic group. Vertebral mineral density (VMD) was measured by quantitative computed tomography in 43 of the corticosteroid-treated cases and in all the normal postmenopausal women; analysis by VMD yielded similar conclusions.
authors.affiliation: Division of Clinical Chemistry, Institute of Medical and Veterinary Science, Adelaide, South Australia.
authors.forename: H A
authors.initials: HA
authors.lastname: Morris
authors.forename: A G
authors.initials: AG
authors.lastname: Need
authors.forename: P D
authors.initials: PD
authors.lastname: O'Loughlin
authors.forename: M
authors.initials: M
authors.lastname: Horowitz
authors.forename: A
authors.initials: A
authors.lastname: Bridges
authors.forename: B E
authors.initials: BE
authors.lastname: Nordin
mesh_terms: D000305:Adrenal Cortex Hormones / Q000009:adverse effects*; D002117:Calcitriol / Q000097:blood; D002136:Calcium, Dietary / Q000493:pharmacokinetics*; D005260:Female; D050723:Fractures, Bone / Q000209:etiology / Q000378:metabolism; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects; D008875:Middle Aged; D010024:Osteoporosis / Q000139:chemically induced / Q000150:complications / Q000378:metabolism*; D013124:Spinal Injuries / Q000209:etiology / Q000378:metabolism
chemical_list: D000305:Adrenal Cortex Hormones; D002136:Calcium, Dietary; D002117:Calcitriol