Pituitary axis
Insulin-like growth factor 1IGF-1
Hepatic mediator of GH action; integrated marker of GH activity over days.
Sample
Serum
Biology
What it measures
GH stimulates hepatic IGF-1 synthesis; IGF-1 mediates most growth effects and feeds back to inhibit GH.
Clinical use
Why we order it
Acromegaly screening (Z-score by age) and treatment monitoring. GH deficiency workup.
Pitfalls
Pre-analytic & interpretation traps
- !Falls in malnutrition, severe liver disease, uncontrolled diabetes, hypothyroidism — interpret in context.