What does the Insulin-like Growth Factor 1 test measure?

Why is Insulin-like Growth Factor 1 measured?

Because it provides a stable, integrated measure of GH action, IGF-1 is the preferred single test for screening disorders of GH excess and deficiency. It is the key biochemical screen for acromegaly, where it is elevated, and a central marker in assessing GH deficiency, where it is low for age. Interpretation is wholly dependent on age- and sex-specific reference ranges, and IGF-1 is also reduced by malnutrition and significant hepatic disease independent of the GH axis.

Reference ranges

Standard reference

Strongly age- and sex-specific; reported against age-banded reference intervals # REVIEWER FLAG: IGF-1 ranges change markedly across the lifespan and are assay-specific — reviewer to confirm Access Medical Laboratories age/sex-banded intervals before publication. SDS (standard deviation score) reporting is preferred where available.

Functional medicine optimal

Within the age- and sex-adjusted reference range; interpreted by SDS rather than a single optimum # REVIEWER FLAG: Functional/anti-ageing 'optimal' framing is not standardised and is potentially contentious — reviewer to confirm positioning.

Units

ng/mL, nmol/L

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.