DETERMINATION OF TOTAL INSULIN (TIRI) IN PLASMA OF INSULIN-TREATED DIABETICS AND NEWBORN-INFANTS OF INSULIN-TREATED DIABETIC MOTHERS

  • 1 January 1975
    • journal article
    • research article
    • Vol. 66  (3) , 356-364
Abstract
Plasma of insulin-treated diabetics and of newborn infants of insulin-treated diabetic mothers contains insulin antibodies which invalidates the radioimmunoassay of insulin. Therefore, the endogenous insulin antibody complex must be split at a pH lower than 5 and the total immunoreactive insulin (TIRI) separated by ethanol extraction. The recovery rate dependence upon plasma volume used for extraction was investigated. By reducing used plasma volume from 500 to 200 .mu.l/extraction the recovery rate increased from 65.1 .+-. 8.4 to 88.3 .+-. 4.2% (mean .+-. SEM). The low plasma volume of 200 .mu.l for TIRI extraction made it possible to determine TIRI during glucose loads of newborn infants. To eliminate different conditions of incubation for standard and unknown plasma samples, TIRI levels were computed by an extracted standard curve, obtained with extracted insulin from standard insulin dilution in insulin-free pooled human plasma. Using the described method a temporary regeneration of insulin secretion in a newly diagnosed juvenile diabetic after insulin treatment was shown. In contrast to newborn infants of healthy mothers, a biphasic insulin release was found during the i.v. glucose loads in newborn infants of insulin-treated diabetic mothers.

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