Calcium malabsorption in the elderly: the effect of treatment with oral 25-hydroxyvitamin D3

Calcium malabsorption is common in the elderly and may contribute to the development of age-related bone loss. To investigate its cause, we have measured radio-calcium absorption, plasma 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D and parathyroid hormone in forty-eight elderly women with a normal plasma creatinine. Calcium malabsorption was associated with low 25-hydroxyvitamin D concentrations and was corrected by increasing these into the normal range by treatment with oral 25-hydroxyvitamin D3. Treatment also increased 1,25-dihydroxyvitamin D, and decreased parathyroid hormone concentrations. Before treatment, plasma parathyroid hormone was related to plasma creatinine but not to 25-hydroxyvitamin D, and the change in absorption on treatment correlated inversely with plasma creatinine. 51Cr EDTA clearance was measured in sixteen elderly women and confirmed that renal impairment was common even with a plasma creatinine in the normal range. Our results suggest that calcium malabsorption in the elderly is predominantly due to vitamin D deficiency; renal impairment is also common and contributes to the malabsorption by increasing the requirements for vitamin D.

Oxalosis in infancy

We describe 3 infants with nephrocalcinosis and terminal renal failure. In all 3 there was widespread oxalate deposition: biochemical evidence of primary hyperoxaluria was sought but the presence of severe renal failure and the lack of established normal values for urinary and plasma oxalate and glycollate in infants made this diagnosis difficult to establish.

[Atypical osteodystrophy of visceral origin (author's transl)]

The authors report a case of atypical osteodystrophy of visceral origin (uretero-sigmoid by-pass for bladder exstrophy) which was characterized by the association of osteocondensation and looser-Milkman lines. They emphasize the rareness of osteodystrophy after uro-digestive by-pass and the exceptional character of the osteocondensation.

[Man in the condition of weightlessness (author's transl)]

In the space flights by the USA and USSR to date adequate experience has been obtained on the adaptation of man to living conditions in space--with the technical assistance of an artificial protective atmosphere in the space ship or space suit--and to the singular factor of "weightlessness" (microgravity, low gravity) and how he re-adjusts again after returning to a gravitational field. There is no ultimate or absolute physiological barrier for long term space flight--with one exception: decalcification of the skeleton. For short space flights, however, space sickness is a serious disorder.

[Idiopathic hypercalciuria: effects of acute phosphorus deficiency (author's transl)]

Eleven patients with kidney stone disease and idiopathic hypercalciuria (urinary calcium above 4 mg/kg/j), without phosphorus renal leak and 6 control subjects have been put for 3 days on a diet containing 1 g calcium and 1 phosphorus daily (period A), and then for 4 days on a diet containing 1 g calcium, 450 mg phosphorus and 3 g aluminium hydroxyde daily (period B). During period A, no significant difference in blood calcium, phosphorus and magnesium, not in phosphaturia, rate of phosphorus reabsorption (RPR) and ratio maximum RPR/creatinine clearance was found between the two groups. After 2 days on a low phosphate diet (period B) the blood phosphorus decreased significantly in the hypercalciuric patients but not in the control subjects, thus revealing among the forme a latent abnormality in the retention of phosphates. This abnormality could play an important role in the pathogenesis of hypercalciuria.

Response of intestinal mucosa to gluten challenge in autistic subjects

Eight autistic patients with steatorrhoea, hypocalciuria, and alleged behavioural improvements on gluten restriction, were fed ordinary diets plus 20 g gluten/day for 4 weeks. None of the patients had any significant change in body-weight or bowel habit as a result of gluten challenge, nor were any histological abnormalities detected on jejunal biopsy. The data suggest that the steatorrhoea and hypocalciuria seen in some autistic subjects cannot be accounted for by the presence of coeliac disease. Furthermore, these patients should not be confined to gluten-free diets, unless rigorous behavioural studies demonstrate a statistically significant improvement in behaviour as a result of the diet, or deterioration during challenge.

Vitamin D binding globulin phenotypes in liver disease

The binding properties towards vitamin D metabolites of plasma from individuals with the three common Gc-globulin phenotypes, Gc-1, Gc-2 and Gc-2-1, have been found to be identical. In patients with liver disease there is a good correlation between the levels of Gc-globulin andalbumin in plasma. In addition the Gc-globulin levels correlate well with the ability of plasma to bind 25-hydroxycholecalciferol. Patients with the Gc-2-1 phenotype showed a significantly smaller depression in plasma Gc-globulin than those with the Gc-2 and Gc-1 phenotypes. The relation of these findings to the pathogenesis of disorders of calcium metabolism in liver disease is discussed.

Evidence that increased circulating 1 alpha, 25-dihydroxyvitamin D is the probable cause for abnormal calcium metabolism in sarcoidosis

Mean plasma 1(alpha),25-dihydroxyvitamin D[1(alpha),25(OH)(2)D] was significantly increased and serum parathyroid hormone was suppressed in three patients with sarcoidosis and hypercalcemia. Prednisone lowered the mean plasma 1(alpha),25(OH)(2)D to normal range and corrected the hypercalcemia. To elucidate the mechanism for the increased sensitivity to vitamin D in this disorder, the effects of orally-administered vitamin D(2) were determined in seven normal subjects, four patients with sarcoidosis and normal calcium metabolism and three patients with sarcoidosis and a history of hypercalcemia who were normocalcemic when studied. Serum and urinary calcium, serum 25-hydroxyvitamin D (25-OHD), plasma 1(alpha),25(OH)(2)D and, in some studies, calcium balance were measured. Vitamin D(2), 250 mug a day for 12 d, produced little, if any, change in mean plasma 1(alpha),25(OH)(2)D and in urinary calcium in the normals and in the patients with normal calcium metabolism. In contrast, vitamin D(2) produced increases in plasma 1(alpha),25(OH)(2)D from concentrations which were within the normal range (20-55 pg/ml) to abnormal values and increased urinary calcium in two patients with abnormal calcium metabolism. In an abbreviated study in the third patient, vitamin D(2), 250 mug a day for 4 d, also increased plasma 1(alpha),25(OH)(2)D abnormally from a normal value. There was a highly significant correlation between plasma 1(alpha),25(OH)(2)D and urinary calcium. Serum 25-OHD and serum calcium remained within the normal range in all subjects and patients. These findings provide evidence that the defect in calcium metabolism in sarcoidosis probably results from impaired regulation of the production and(or) degradation of 1(alpha),25(OH)(2)D. Prednisone may act to correct the abnormal calcium metabolism by reducing circulating 1(alpha),25(OH)(2)D.

[Alteratiions of calcium and phosphorus metabolism in patients treated with duodenoencephalopancreatectomy]

In a followup study of 14 patients treated by duodeno-cephalo-pancreatectomy at least one year before, the authors detected radiological evidence of bone tissue reshuffling in 64 per cent of the cases. Of these, 70 per cent showed high serum alkaline phosphatase content not attributable to cholestasis, liver metastasis, or specific bone disease. The authors call attention to the significance of this biochemical parameter for diagnostic purposes and therapeutic guidance.