# immunoreactive insulin

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## im·mu·no·re·ac·tive in·su·lin

that portion of insulin in blood measured by immunochemical methods for the hormone; presumed to represent the free (unbound) and biologically active fraction of total blood insulin.

## insulin

a double-chain peptide hormone formed from proinsulin in the beta cells of the pancreatic islets of Langerhans. Insulin promotes the storage of glucose and the uptake of amino acids, increases protein and lipid synthesis, and inhibits lipolysis and gluconeogenesis.
The secretion of endogenous insulin is a response of the beta cells to a stimulus. The primary stimulus is glucose; others are amino acids, particularly leucine, and the 'gut hormones', such as secretin, pancreozymin and gastrin. These chemicals play an important role in maintaining normal blood glucose levels by triggering the release of insulin after ingestion of a meal.
Commercially prepared insulin is available in various types, which differ in the speed with which they act and in the duration of their effectiveness. There are three main groups: rapid acting (regular or semilente), intermediate acting (isophane suspension or NPH, zinc suspension or lente), and long acting (protamine zinc suspension or PZI, or ultralente). Mixtures are also marketed.

insulin deficiency
diabetes mellitus.
insulin-dextrose therapy
a combination used in emergencies to lower blood potassium levels in acute hypoadrenocorticism.
insulin:glucagon ratio
ratio of insulin to glucagon; thought to determine the predominance of the action of one hormone over the other.
insulin:glucose ratio
a comparison of simultaneously obtained blood levels of immunoreactive insulin and plasma glucose. An increased ratio suggests an insulin-secreting tumor of the pancreas. A modification is the amended insulin:glucose ratio, based on the calculation:
$$\vskip13.5pt{\rm {serum\ insulin (\rmmu U/ml)\times100} \over {\rm plasma \ glucose (mg/dl) - 30}$$
immunoreactive insulin
radioimmunoassay methods are used in determining blood levels of insulin. Increased levels are found with hypoglycemia caused by functional islet cell tumors.
insulin pump
a device consisting of a syringe filled with a predetermined amount of short-acting insulin, a plastic cannula and a needle, and a pump that periodically delivers the desired amount of insulin. Sometimes used in humans, but of limited application in animals.
insulin sensitivity test, insulin response test
used to differentiate diabetes mellitus from pituitary and adrenal diabetes. A test dose of exogenous insulin will produce a rapid and marked decrease in blood glucose if the pancreas is not secreting sufficient insulin. A much less dramatic response is produced if hyperglycemia is due to excessive secretion of either pituitary or adrenocortical hormones rather than insufficient insulin production.
insulin syringe
disposable syringe with a capacity of 1 ml or less and a fine gauge needle (27-29G) attached, and graduation markings corresponding to insulin units in standard preparations. Needles may also be treated to minimize pain on injection.
References in periodicals archive ?
Synthesis of immunoreactive insulin in vitro by aplastic mammary carcinoma preconditioned in diabetic mice.
The specific determination of insulin lispro offers advantages over measuring total concentrations of immunoreactive insulin and would be particularly useful in assessing the pharmacokinetics of insulin lispro in patients with insulin resistance and in documenting factitious hypoglycemia from injection of insulin lispro.
In healthy subjects, the contribution of intact proinsulin and conversion intermediates is relatively low, representing at most 10-20% of immunoreactive insulin.

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