Igf 1
Insulin-like growth factor 1, a measure of growth-hormone activity. Reference ranges are strongly age-dependent.
What Igf 1 measures
IGF-1 (insulin-like growth factor 1) is a hormone made mainly by the liver in response to growth hormone released by the pituitary gland. It carries out many of growth hormone's effects on tissues throughout the body, supporting growth and repair.
Because growth hormone is released in short pulses and clears from the blood quickly, it is hard to measure directly. IGF-1 is far more stable across the day, so clinicians use it as a practical, convenient marker of overall growth-hormone activity.
Normal IGF-1 levels are strongly age-dependent: they are highest during adolescence, when growth is most active, and gradually decline through adulthood and into older age. For that reason your result is always read against age-specific expectations rather than a single fixed value.
What a high Igf 1 can mean
A high IGF-1 for your age can suggest excess growth-hormone activity in the body. The classic cause in adults is acromegaly, in which a benign tumour of the pituitary gland drives too much growth hormone, which in turn pushes IGF-1 upward over time.
Because normal IGF-1 falls with age, a value that would be ordinary in a teenager may be clearly elevated in an older adult. This is why results are interpreted against age-specific reference expectations rather than one universal cut-off.
A single high reading is not a diagnosis. Clinicians typically confirm the picture with additional tests, such as growth-hormone measurements during a glucose challenge and sometimes pituitary imaging, before drawing conclusions. Interpretation belongs with a qualified clinician who can weigh your full history, symptoms, and other results together.
What a low Igf 1 can mean
A low IGF-1 for your age can suggest reduced growth-hormone activity, and in some cases growth-hormone deficiency involving the pituitary gland. However, a low value has many other possible explanations and is rarely meaningful on its own.
Poor nutrition or prolonged calorie restriction, liver disease (since the liver produces most IGF-1), and uncontrolled diabetes can all lower levels. Simply being older also brings IGF-1 down, which is a normal part of ageing rather than a problem.
Because of this, the result is always read against age norms and alongside other tests rather than in isolation. A clinician will consider your overall health, medications, symptoms, and additional bloodwork before deciding whether any further evaluation is warranted, and what it might mean for you.
Track your Igf 1 over time in Quanome — it reads your lab reports (PDF or photo) on your device, charts each marker against its range, and an AI coach explains what your trends mean alongside your Apple Health and DNA.