Isotopic determination of intestinal calcium absorption in normal subjects

1. Gastro-intestinal absorption of calcium was studied in man by the measurement of forearm radioactivity in a large-volume liquid scintillation counter following separate oral and intravenous doses of 47CaCl2. From the ratio of the percentages of total radioactivity appearing in the forearm following these separate determinations the fractional absorption of calcium was estimated. 2. Changes of forearm radioactivity with time following the administration of this isotope were studied; evidence is presented that the radioactivity in the forearm at 4 h after administration of the isotope gives a valid assessment of fractional calcium absorption. 3. Fractional calcium absorption determined by this technique correlated well with the net calcium absorption as determined from stool radioactivity after oral administration of isotope. 4. In normal subjects it was shown that fractional calcium absorption measured by this technique varies inversely with the stable calcium load and that the absolute amount of calcium absorbed from given loads increases with the size of the load in the range 20–1000 mg calcium. 5. Gastro-intestinal calcium absorption was measured at various oral calcium loads in a group of fifteen patients with recurrent calcium-containing renal stones. All the patients were normocalcaemic; some had hypercalciuria. In the patients with hypercalciuria, calcium absorption, fractional and absolute, was significantly increased at all calcium loads as compared to that of patients with normal urinary calcium. 6. It is concluded that hyperabsorption of calcium from the gastro-intestinal tract plays a crucial role in the aetiology of hypercalciuria, probably by causing an increase in the renal filtered calcium load.

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The Effect of Parathyroid extract Administration on Gastro-Intestinal Calcium Absorption in Normal Subjects

Clinical Science ◽

10.1042/cs038017pa ◽

1970 ◽

Vol 38 (3) ◽

pp. 17P-17P

Author(s):

M. R. Wills ◽

C. Y. C. Pak ◽

F. C. Bartter

Keyword(s):

Calcium Absorption ◽

Normal Subjects ◽

Intestinal Calcium Absorption ◽

Parathyroid Extract

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Measurement of Oral Calcium Absorption from the Gut by External Isotope Counting

Journal of The Royal Naval Medical Service ◽

10.1136/jrnms-57-88 ◽

1971 ◽

Vol 57 (2) ◽

pp. 88-91

Author(s):

Murdoch A. Macleod

Keyword(s):

Vitamin D ◽

Renal Failure ◽

Calcium Metabolism ◽

Calcium Absorption ◽

Normal Subjects ◽

Intestinal Calcium Absorption ◽

Calcium Balance ◽

Oral Calcium ◽

Absorption Current ◽

Reliable Methods

AbstractAmong the factors which regulate normal gastro-intestinal calcium absorption, current thought recognises calcium intake, vitamin D and parathyroid hormone as playing an important part. It is well documented that gastro-intestinal calcium absorption is reduced in states of malabsorption, hypoparathyroidism and in patients with chronic renal failure, and raised in states of hyperparathyroidism, urolithiasis and idiopathic hypercalcuria.Difficulties inherent in classic calcium-balance techniques have prompted a search for more practical and reliable methods of measuring the degree of impairment of calcium absorption. This paper describes a study of intestinal calcium absorption in 10 normal subjects and four patients, with various disorders of calcium metabolism, using an external radio-isotope counting technique.

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Determination of Factor XIII Activity and of Factor XIII Inhibitors Using an Ammonium-Sensitive Electrode

Thrombosis and Haemostasis ◽

10.1055/s-0038-1665256 ◽

1983 ◽

Vol 50 (02) ◽

pp. 563-566 ◽

Cited By ~ 3

Author(s):

P Hellstern ◽

K Schilz ◽

G von Blohn ◽

E Wenzel

Keyword(s):

Factor Xiii ◽

Normal Subjects ◽

The Other ◽

Activity Measurement ◽

Factor Xiii Deficiency ◽

Assay Procedure ◽

Stabilization Factor ◽

Release Method ◽

Sensitive Electrode

SummaryAn assay for rapid factor XIII activity measurement has been developed based on the determination of the ammonium released during fibrin stabilization. Factor XIII was activated by thrombin and calcium. Ammonium was measured by an ammonium-sensitive electrode. It was demonstrated that the assay procedure yields accurate and precise results and that factor XIII-catalyzed fibrin stabilization can be measured kinetically. The amount of ammonium released during the first 90 min of fibrin stabilization was found to be 7.8 ± 0.5 moles per mole fibrinogen, which is in agreement with the findings of other authors. In 15 normal subjects and in 15 patients suffering from diseases with suspected factor XIII deficiency there was a satisfactory correlation between the results obtained by the “ammonium-release-method”, Bohn’s method, and the immunological assay (r1 = 0.65; r2= 0.70; p<0.01). In 3 of 5 patients with paraproteinemias the values of factor XIII activity determined by the ammonium-release method were markedly lower than those estimated by the other methods. It could be shown that inhibitor mechanisms were responsible for these discrepancies.

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GASCHROMATOGRAPHIC DETERMINATION OF STEROIDS IN THE URINE OF PATIENTS WITH CUSHING'S SYNDROME

Acta Endocrinologica ◽

10.1530/acta.0.0670303 ◽

1971 ◽

Vol 67 (2) ◽

pp. 303-315 ◽

Cited By ~ 14

Author(s):

A. J. Moolenaar ◽

A. P. van Seters

Keyword(s):

Liquid Chromatography ◽

Cushing’S Syndrome ◽

Normal Subjects ◽

Diagnostic Value ◽

Cushing's Syndrome ◽

Gas Liquid Chromatography ◽

Obese Subjects

ABSTRACT The 17-oxosteroids were estimated in the urine of 27 patients with Cushing's syndrome by gas-liquid chromatography (G. L. C.). The values of the various steroid fractions are compared with those of normal subjects, patients with thyrotoxicosis and obese subjects. The effect of the age of the patients on the diagnostic value of the invidual 17-oxosteroids and their ratios is discussed.

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SIMPLIFIED DEXAMETHASONE SUPPRESSION TEST

Acta Endocrinologica ◽

10.1530/acta.0.0610219 ◽

1969 ◽

Vol 61 (2) ◽

pp. 219-231 ◽

Cited By ~ 14

Author(s):

V. H. Asfeldt

Keyword(s):

Cushing’S Syndrome ◽

Normal Subjects ◽

Cushing's Syndrome ◽

Dexamethasone Suppression Test ◽

Clinical Value ◽

Suppression Test ◽

The One ◽

Steroid Excretion ◽

Dexamethasone Suppression

ABSTRACT This is an investigation of the practical clinical value of the one mg dexamethasone suppression test of Nugent et al. (1963). The results, evaluated from the decrease in fluorimetrically determined plasma corticosteroids in normal subjects, as well as in cases of exogenous obesity, hirsutism and in Cushing's syndrome, confirm the findings reported in previous studies. Plasma corticosteroid reduction after one mg of dexamethasone in cases of stable diabetes was not significantly different from that observed in control subjects, but in one third of the insulin-treated diabetics only a partial response was observed, indicating a slight hypercorticism in these patients. An insufficient decrease in plasma corticosteroids was observed in certain other conditions (anorexia nervosa, pituitary adenoma, patients receiving contraceptive or anticonvulsive treatment) with no hypercorticism. The physiological significance of these findings is discussed. It is concluded that the test, together with a determination of the basal urinary 17-ketogenic steroid excretion, is suitable as the first diagnostic test in patients in whom Cushing's syndrome is suspected. In cases of insufficient suppression of plasma corticosteroids, further studies, including the suppression test of Liddle (1960), must be carried out.

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DETERMINATION OF BLOOD CORTICOIDS USING THE IN VITRO RESIN UPTAKE OF 3H-PREDNISOLONE

Acta Endocrinologica ◽

10.1530/acta.0.0570023 ◽

1968 ◽

Vol 57 (1) ◽

pp. 23-32 ◽

Cited By ~ 2

Author(s):

Hironori Nakajima ◽

Mitsunori Murala ◽

Masumitsu Nakata ◽

Takeshi Naruse ◽

Seiji Kubo

Keyword(s):

Thyroid Function Test ◽

Normal Subjects ◽

Adrenal Function ◽

Function Test ◽

Before And After ◽

Adrenal Response ◽

Suppression Test

ABSTRACT The in vitro resin uptake of 3H-prednisolone was used for the determination of blood cortisol after addition of radioactive prednisolone followed by Amberlite CG 400 Type 1 to the test serum, and incubation of the mixture. The radioactivity of the supernatant was compared before and after the addition of the resin. The principle of this method is similar to that of the 131I-triiodothyronine resin uptake for the thyroid function test. The tests for the specificity, reproducibility and sensitivity gave satisfactory results. The mean basal value ± SD of the 3H-prednisolone resin uptake was 35.3 ± 9.2% in normal subjects, and 27.1 ± 4.8% in pregnant women. This method was valid in various adrenal function tests, i. e. the adrenal circadian rhythm, corticotrophin (ACTH) test, dexamethasone suppression test and the adrenal response to lysine-8-vasopressin. It proved to be a sensitive indicator of the adrenal function. These results suggest that this method should be useful for a routine adrenal function test.

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