Intestinal calcium absorption

Concurrent use of oral and intravenous tracers and calculation by the inverse convolution method

Janusz Szymendera, Robert P. Heaney, Paul D. Saville

Research output: Contribution to journalArticle

50 Citations (Scopus)

Abstract

Serum calcium specific activity curves following concurrent oral and intravenous doses of 2 radioisotopes of calcium were obtained in 20 normal women averaging 41 years of age, and in 10 osteoporotics averaging 65 years. Calcium absorption rate was calculated over a 4 hour period using an inverse convolution function of the 2 specific activity curves. The maximum rate of absorption occurred at an average of 15.6 minutes after ingestion and decreased monoexponentially thereafter. This finding is consistent with animal studies indicating that calcium absorption occurs maximally in the first part of the small intestine. Fractional absorption of the test load was calculated from integration of the absorption rate curve and was found to be identical both to the average equilibrium quotient, 47Ca/45Ca, observed in the blood and urine samples collected from these patients over several days, and to absorption estimated from external recovery of the oral tracer. Absorption was higher in the normal women than in 6 untreated osteoporotics, but 5 osteoporotics given ethane-1-hydroxy-1,1-diphosphonate had a higher rate than either group. Neither of these differences was statistically significant.

Original languageEnglish
Pages (from-to)570-578
Number of pages9
JournalThe Journal of Laboratory and Clinical Medicine
Volume79
Issue number4
StatePublished - 1972
Externally publishedYes

Fingerprint

Intestinal Absorption
Convolution
Calcium Radioisotopes
Calcium
Ethane
Diphosphonates
Animals
Blood
Recovery
Small Intestine
Eating
Urine
Serum

All Science Journal Classification (ASJC) codes

  • Medicine(all)
  • Pathology and Forensic Medicine

Cite this

Intestinal calcium absorption : Concurrent use of oral and intravenous tracers and calculation by the inverse convolution method. / Szymendera, Janusz; Heaney, Robert P.; Saville, Paul D.

In: The Journal of Laboratory and Clinical Medicine, Vol. 79, No. 4, 1972, p. 570-578.

Research output: Contribution to journalArticle

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