Choice and use of tracers

P. C. Butler, P. Bell, R. Rizza

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

The isotope dilution method has been widely employed to measure glucose turnover in man. The validity of this technique depends upon several assumptions. First, it is assumed that the selected model of glucose kinetics is valid. Under nonsteady state conditions this has recently been challenged for the most commonly used single compartment model. Secondly, it is assumed that the isotope is metabolized in the same manner as unlabeled glucose. If the isotope loses its label when subject to a substrate cycle (for example, [2-3H]glucose in glucose to glucose 6-phosphate cycling), and overestimate of glucose disposal will result. In contrast, if isotope that has been cleared (for example [6-3H]glucose in hepatic glucogen) is recycled into the systemic circulation, an underestimation of glucose turnover will result. Thirdly, it is assumed that measurement of specific activity is accurate. It has recently been shown that many commercially available tritiated (but not 14C) isotopes contain radioactive nonglucose contaminants which have a slower clearance rate than glucose under conditions of high glucose turnover. This can result in overestimates of specific activity and underestimates of glucose appearance, leading to calculated negative hepatic glucose release. While this problem may be avoided with purified tritiated glucose tracers, a similar problem with stable isotopes of glucose remains to be determined. In summary, the choice of glucose isotope should reflect the probability of substrate cycling and isotope cycling in the experiment in question. Care should be taken to ensure purified isotopes are selected and that the model of glucose kinetics used is valid during the conditions to be studied.

Original languageEnglish (US)
Pages (from-to)20-25
Number of pages6
JournalHormone and Metabolic Research
Volume24
Issue numberSUPPL.
StatePublished - 1990

Fingerprint

Glucose
Isotopes
Substrate Cycling
Glucose-6-Phosphate
Kinetics
Liver
Substrates
Radioisotopes
Dilution
Labels
Impurities

Keywords

  • futile cycling
  • glucose turnover
  • isotope
  • isotope cycling
  • nonsteady state
  • steady state

ASJC Scopus subject areas

  • Biochemistry
  • Endocrinology

Cite this

Butler, P. C., Bell, P., & Rizza, R. (1990). Choice and use of tracers. Hormone and Metabolic Research, 24(SUPPL.), 20-25.

Choice and use of tracers. / Butler, P. C.; Bell, P.; Rizza, R.

In: Hormone and Metabolic Research, Vol. 24, No. SUPPL., 1990, p. 20-25.

Research output: Contribution to journalArticle

Butler, PC, Bell, P & Rizza, R 1990, 'Choice and use of tracers', Hormone and Metabolic Research, vol. 24, no. SUPPL., pp. 20-25.
Butler PC, Bell P, Rizza R. Choice and use of tracers. Hormone and Metabolic Research. 1990;24(SUPPL.):20-25.
Butler, P. C. ; Bell, P. ; Rizza, R. / Choice and use of tracers. In: Hormone and Metabolic Research. 1990 ; Vol. 24, No. SUPPL. pp. 20-25.
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