⚠️ Educational only. LabPlain does not provide medical advice or diagnosis. Always discuss your specific results with your healthcare provider.
What this test measures
IGF-1 stands for Insulin-like Growth Factor 1. It is a hormone primarily produced by your liver in response to signals from Growth Hormone (GH), which is released by your brain's pituitary gland. As its name implies, IGF-1 plays an essential role in managing cell growth, tissue regeneration, bone development, and muscle maintenance throughout your life.
While Growth Hormone is released in short, unpredictable spikes during the day and night (making it very difficult to measure accurately with a single blood draw), IGF-1 levels remain highly stable in your bloodstream. Because of this stability, doctors use an IGF-1 test as an indirect and highly reliable snapshot of your body's overall growth hormone activity.
A healthcare provider typically orders this test if they suspect a disorder related to growth hormone production, such as an underactive pituitary gland or conditions involving an overproduction of growth hormones.
Unlike many blood markers, standard ranges for IGF-1 are deeply dependent on your age and stage of development. Levels peak dramatically during puberty when bones and tissues are growing rapidly, and then slowly drop as you age into adulthood.
Because reference ranges are highly specialized by age bracket and vary widely from lab to lab, you must compare your number against the unique reference chart provided on your official laboratory paperwork.
📊 Age over time
Because your age dictates what "normal" looks like, a result of 280 ng/mL might be perfectly healthy for a 30-year-old, but could be flagged as significantly elevated for an individual in their late 60s. Your doctor will interpret your results specifically against your age bracket.
What your result might indicate
↑ If High
An elevated IGF-1 level suggests that your body may be producing excess growth hormone. In adults, prolonged overproduction can be associated with acromegaly, a condition leading to the slow enlargement of bones and tissues. A single high reading requires more detailed clinical follow-up.
↓ If Low
A lower-than-expected IGF-1 level can indicate an overall growth hormone deficiency or a state of undernutrition. In adults, it may point toward hypopituitarism (a sluggish pituitary gland). It can also indicate that the liver is struggling to manufacture the hormone due to lifestyle or systemic factors.
Symptoms associated with abnormal IGF-1
↑ High IGF-1 Symptoms
Enlargement of hands, feet, or facial features
Joint pain, swelling, or numbness (Carpal Tunnel)
Coarsening of skin or excessive sweating
Deepening of the voice
Fatigue or muscle weakness
Frequent headaches or vision issues
Unexplained gaps forming between teeth
↓ Low IGF-1 Symptoms
Persistent fatigue or low physical stamina
Decreased muscle mass and increased body fat
Reduced bone density or frequent fractures
Poor mood, anxiety, or lack of motivation
Slow wound healing
Disrupted sleep patterns
Changes in blood lipid levels
Common causes of abnormal IGF-1
What can raise IGF-1?
The primary clinical driver behind significantly high IGF-1 levels is a non-cancerous tumor on the pituitary gland that overproduces growth hormone (a condition known as acromegaly in adults, or gigantism if it occurs in children before bone plates close).
Beyond clinical conditions, transient or mild elevations can sometimes be associated with high-protein diets, pregnancy, or the use of synthetic human growth hormone therapies.
What can lower cortisol or IGF-1?
A low IGF-1 level is frequently associated with an underactive pituitary gland that is failing to supply adequate growth hormone. However, because the liver builds IGF-1, chronic liver disease or liver resistance can also lower your levels.
Systemic nutritional deficits—such as severe fasting, malnutrition, or anorexia—can prevent the liver from synthesizing the hormone properly. Poorly controlled diabetes, thyroid issues, or normal hormonal declines from advanced aging can also be associated with lower readings.
Tests often ordered alongside IGF-1
Because IGF-1 provides a structural look at growth hormone pathways, it is routinely paired with dynamic evaluations:
Growth Hormone (GH) — checked under specific testing protocols to assess instantaneous pituitary output
Oral Glucose Tolerance Test (OGTT) — a diagnostic evaluation where sugar is consumed to see if it properly suppresses growth hormone production
Growth Hormone Releasing Hormone (GHRH) Test — evaluates how well your pituitary responds to chemical messengers
Comprehensive Metabolic Panel (CMP) — looks closely at kidney and liver function, as the liver creates IGF-1
Prolactin and Cortisol — assesses if other hormones controlled by the pituitary gland are working in balance
What to do next
An out-of-range IGF-1 result is a single piece of a larger health picture and is not a definitive diagnosis on its own. Because your age, dietary patterns, and overall metabolic status influence this hormone, your doctor will look at your numbers alongside your specific physical symptoms. Avoid jumping to conclusions before a professional clinical assessment.
Questions to ask your doctor
01Is my IGF-1 result considered normal and expected for a person of my specific age?
02Could my current symptoms be related to this specific high or low reading?
03Do you recommend a dynamic follow-up evaluation, like a glucose suppression test, to check my growth hormone stability?
04Could my nutritional habits, fasting, or any existing medications be skewing this data?
05Based on these markers, would it be helpful for me to consult with an endocrinologist?
Frequently asked questions
Can a single Growth Hormone test replace an IGF-1 test?
Generally, no. Growth hormone drops and spikes continuously throughout the day. A random blood draw could show a level near zero or a brief massive peak entirely by chance. Because IGF-1 remains incredibly steady, it acts as a reliable metric of your 24-hour growth hormone trend.
Can diet or lifestyle affect my IGF-1 numbers?
Yes. Periods of prolonged fasting, strict low-calorie diets, or severe malnutrition can prompt your IGF-1 levels to drop significantly because your body lacks the raw materials required by the liver to synthesize the hormone. Conversely, high-protein diets may marginally bump levels upward.
What is the connection between IGF-1 and acromegaly?
Acromegaly is a rare condition occurring in adults when a benign pituitary tumor creates excessive growth hormone, which causes the liver to release high amounts of IGF-1. This causes a slow, progressive expansion of bone structures in the face, jaw, hands, and feet. Measuring IGF-1 is one of the primary tools used to screen for this condition.
Does low IGF-1 always mean I need hormone replacement therapy?
Not necessarily. Mildly low IGF-1 can stem from aging, poor metabolic health, sleep issues, or dietary deficits. Addressing underlying issues such as sleep hygiene, proper nutrition, and liver health often helps normalize levels without requiring therapeutic hormone interventions.