Authors: David R Clemmons
Publish Date: 2007/04/11
Volume: 10, Issue: 2, Pages: 121-128
Abstract
The diagnosis of disorders of growth hormone GH is dependent upon accurate measurement of insulinlike growth factorI IGFI concentrations since serum IGFI assays have been found to be useful as a screening tests for the presence of growth hormone deficiency GHD in children and in both children and adults they have been found very useful in establishing the diagnosis of acromegaly IGFI is also used extensively to monitor the response to GH treatment in children and adults and to monitor the response to treatment in acromegaly Since IGFI is influenced by several other hormones and physiologic factors as well as GH a knowledge of its regulation is essential to understanding how to properly interpret the measurements Several technical criteria are required for successful laboratory estimation of IGFI values These include elimination of interference of IGFIbinding proteins IGFBP utilization of adequate numbers of normal subjects to define the normal ranges and importantly the use of high affinity high specificity antisera that allow precise and reproducible measurements of the biologically active peptide Cross comparisons of various commercial assays show that the results generally are similar when values are in the normal range However the assays have different performance characteristics when concentrations are either above or below the normal range To obtain cross laboratory standardization for values outside the normal range requires utilization of similar highquality reagents and techniques that are reasonably comparable Without this degree of standardization cross comparisons among various reference laboratories are likely to continue to show wide divergence for values that are above or below the 95 confidence interval A future goal should be the development of standard procedures and reagents that eliminate this degree of variability
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