RESUMO
A simplified method is described for the measurement of calcium absorption in the dog. This method uses 45Ca and takes less than 8 h to perform. Calcium absorption was measured in normal and uremic dogs on different intakes of calcium and phosphorus and compared to the results obtained in the same animal maintained on the same diet by another method using 47Ca and a double dilution procedure. The correlation coefficient between the two methods was 0.99 (P < 0.001). The advantages of the simplified method are discussed.
Assuntos
Cálcio/metabolismo , Absorção Intestinal , Uremia/metabolismo , Animais , Calcifediol , Radioisótopos de Cálcio , Cálcio da Dieta/farmacologia , Dieta , Cães , Feminino , Hidroxicolecalciferóis/farmacologia , Métodos , Fosfatos/deficiência , Fósforo/administração & dosagem , Técnica de Diluição de RadioisótoposRESUMO
Fractional intestinal absorption of calcium was measured in 41 haemodialysed patients 4 hours after an oral dose of 47 Ca. Fractional intestinal calcium absorption was 40.3 +/- 1.9% (SEM) when measured 10 to 12 hours after a haemodialysis session (dialysate calcium concentration: 1.75 mmol/litre). This value was significantly lower (p less than 0.001) than that in 26 healthy controls (56.8 +/- 1.8%) and higher (p less than 0.05) than that of 35 patients with chronic renal failure treated conservatively (34.5 +/- 2.1%). In 17 patients, fractional intestinal calcium absorption was measured just before and just after a dialysis session. Pre-dialysis fractional intestinal calcium absorption (33.7 +/- 3.0%) was not significantly different from fractional intestinal calcium absorption in uraemic patients treated conservatively, while after dialysis fractional intestinal calcium absorption had increased significantly to 42.0 +/- 2.6% (p less than 0.001). It is suggested that the transient increase in fractional intestinal calcium absorption observed after dialysis could be related to dialysis induced volume depletion rather than to a vitamin D-dependent mechanism.
