Intestinal calcium absorption as shown by stable strontium test in celiac disease before and after gluten-free diet.

OBJECTIVES: To investigate the effect of gluten-free diet on mineral and bone metabolism in women with celiac disease and, using the strontium test, to assess intestinal calcium absorption.
METHODS: We studied body mass index, biochemical and bone mineral indices, strontium absorption test, and bone mineral density in 18 women (mean age 36.8 yr, range 18-68 yr) with celiac disease at diagnosis and after 12 months of gluten-free diet.
RESULTS: Mean strontium absorption at diagnosis was markedly decreased with respect to control values (13.84 +/- 9.03% vs 22.47 +/- 4.21%, p < 0.0001), and 11 of the 18 patients (61%, subgroup A) had low values. In all patients, mean hemoglobin, serum potassium, magnesium, plasma calcium, urinary calcium, and phosphorus were significantly abnormal at diagnosis, whereas only the subgroup A had significantly reduced body mass index, 25 OH vitamin D, and elevated alkaline phosphatase. This subgroup differed in body mass index (p < 0.003) and calciuria (p < 0.035) with respect to the other patients. Strontium absorption correlated with body mass index, calcemia, and 25 OH vitamin D. After the gluten-free diet, all biochemical variables and strontium absorption normalized (23.23 +/- 5.54%), whereas bone mineral density did not change.
CONCLUSIONS: At diagnosis, the patients frequently had intestinal calcium malabsorption, as demonstrated by strontium test, with an early renal compensatory mechanism. After the gluten-free diet, the normalization of calcium absorption and the decrease of mid-molecule parathyroid hormone suggested a normalization of mineral metabolism, although a positive effect on bone mineral density was not evident at that time.