Relationship between fractional calcium absorption and gastric emptying

Abstract

Abstract.The relationship between calcium absorption and gastric emptying and the precision of measurement of fractional calcium absorption using a single isotope technique were evaluated in 14 normal postmenopausal women (age range 61 -72 years). On two occasions separated by between 5 and 15 days, each subject was given 250mL water containing 0.2MBq of 45Ca in 20mg of calcium carrier as the chloride, 20 mg kg-I paracetamol and 9 MBq of 9 9 m T~ sulphur colloid. Venous blood samples were taken at -2, 15, 30, 45, 60, 90, 120, 150 and 180min after consumption of the drink, and gastric emptying (GE) was monitored with a gamma camera. Fractional calcium absorption in the first hour (a6) was calculated from the blood samples obtained at 15, 30, 45, 60, 90 and 120min. An absorption rate was also derived from the 60 min sample using only a calibration curve ( a l ) .There were close correlations between radiocalcium absorption on the two study days (r = 0.89, P < 0.001 for both a I and ' Y 6 ) and between al and a 6 (r = 0.93, P < 0,001). Plasma paracetamol concentrations at 15 min were directly related to the early phase of GE ( r = 0.42, P c 0.05). In contrast, calcium absorption was inversely related to GE (r = 0.45, P < 0.05). We conclude that radiocalcium absorption is not greatly influenced by gastric emptying rate and that the single blood sample procedure has similar precision to the six-blood sample test.

Effect of Difructose Anhydride III on Calcium Absorption in Humans

“…Previous other studies on these effects have used radioisotopes or stable isotopes in clearance and other such tests. [8][9][10] We used the urinary calcium excretion as an indicator of calcium absorption. This method is based on the positive correlation between the intestinal calcium absorption and urinary calcium excretion and has often been used.…”

Effect of Lactulose on Calcium and Magnesium Absorption: A Study Using Stable Isotopes in Adult Men

“…A high 44 Ca or 25 Mg ratio in the urine after digestion of the test food indicates that the absorption of the mineral was also relatively high. Unlike the double-labeling method, the single-labeling method cannot be used to measure the true absorption, but it has been shown to exhibit a high correlation with the double-labeling method (13,14), and its accuracy can be improved if the body size is included in the regression equation (15, 16); however, this method has needed ingestion of radioactive tracer. With the parallel design, it is impossible to measure the absorption of Ca or Mg using a single isotope method without adjusting by body size.…”

Guide for judicious use of the paracetamol absorption technique in a study of gastric emptying rate of liquids

“…Some investigators have found a significant correlation between the parameters for the rate of paracetamol absorption and scintigraphically measured gastric half-emptying time, the "gold standard" for GER measurement, 9,[12][13][14][15] but others have failed to find such correlation. 16,17 Based on the absence of "significant" correlation, the validity of the paracetamol method has been challenged.…”