Growth Hormone (Serum)
Your body's master repair and recovery hormone — but a single blood test for it is almost useless. Here's why, and what to test instead.
Growth hormone (GH) drives cell repair, fat burning, and muscle maintenance. But it's released in pulses — mostly during deep sleep — so a random blood draw can be near zero even when your GH production is perfectly healthy. For routine assessment, IGF-1 is the better test.
What is this test?
Growth hormone is made by your pituitary gland — a pea-sized gland at the base of your brain. It triggers your liver to produce IGF-1, which then carries out most of GH's effects: building muscle, burning fat, repairing tissue, and maintaining bone density.
The problem with testing serum GH directly is that it's pulsatile. Your pituitary releases GH in bursts — the largest during deep (slow-wave) sleep, with smaller pulses after exercise or fasting. Between pulses, your GH level can be essentially zero. So a random blood draw is like checking the weather by looking out the window for one second.
That's why endocrinologists use stimulation tests (like the insulin tolerance test or arginine-GHRH test) when they truly need to assess GH function. For everyone else, IGF-1 is the practical proxy — it reflects your average GH output over days to weeks and can be drawn at any time.
What your number means
A random serum GH value has limited clinical meaning by itself. The ranges below are reference values, but your result depends entirely on when the blood was drawn relative to your last GH pulse.
| GH Level (ng/mL) | Context |
|---|---|
| < 0.1 | Likely between pulses — normal for a random draw. Only concerning on a stimulation test. |
| 0.1–3 | Typical random value in adults. Doesn't tell you much without IGF-1 context. |
| 3–8 | Likely caught during or near a pulse. May be normal, or could suggest stimulation from exercise/fasting. |
| > 10 | Unusually high for a random draw. Investigate — could indicate a GH-secreting pituitary adenoma (acromegaly). |
Bottom line: Don't over-interpret a single GH number. If you're curious about your GH status, ask your doctor for an IGF-1 test — it's stable, reliable, and doesn't require any special timing.
How to support healthy GH levels naturally
Sleep and body composition matter far more than any supplement. GH declines ~15% per decade after age 30, but lifestyle interventions can meaningfully slow that decline.
- Prioritise deep sleep — 70–80% of daily GH is released during slow-wave sleep. Poor sleep quality crushes GH output more than anything else.
- High-intensity exercise — Sprint intervals and heavy resistance training trigger the largest exercise-induced GH pulses
- Reduce body fat — Excess visceral fat suppresses GH secretion; losing fat directly improves pulsatile release
- Intermittent fasting — Fasting for 16–24 hours increases GH secretion 2–5x as the body shifts to fat mobilisation
- Keep blood sugar stable — Insulin and GH are antagonistic; chronic hyperinsulinaemia suppresses GH release
- Avoid eating before bed — A carb-heavy meal before sleep blunts the nocturnal GH surge via insulin
Tracking IGF-1 alongside your GH interventions?
eterni tracks your IGF-1, sleep data, and body composition together — so you can see what's actually moving the needle.
Get early accessFrequently Asked Questions
Why is a single GH blood test unreliable?
Growth hormone is released in pulses — mostly during deep sleep and exercise. Between pulses, your GH can be near zero even if your overall production is perfectly normal. A random blood draw might catch a peak or a trough, making the result almost meaningless by itself. That's why doctors use IGF-1 (which stays stable throughout the day) or stimulation tests to properly assess GH status.
GH vs IGF-1 — which should I test?
For routine screening, IGF-1 is far more useful. It reflects your average GH output over days to weeks, doesn't fluctuate hour to hour, and can be drawn at any time. Serum GH is mainly useful in stimulation or suppression tests ordered by endocrinologists — not for general health screening.
Does fasting boost growth hormone?
Yes, significantly. Studies show GH increases 2–5x during a 24-hour fast, with even larger spikes during 48–72 hour fasts. This is one of the body's mechanisms for preserving muscle and mobilising fat during food scarcity. Intermittent fasting (16:8) also modestly increases GH pulsatility, though the effect is smaller than extended fasts.
Do peptides like ipamorelin actually raise GH?
Yes, GH-releasing peptides (ipamorelin, sermorelin, CJC-1295) stimulate your pituitary to release more of its own growth hormone. They produce measurable GH spikes on blood tests and increases in IGF-1 over weeks of use. However, they require medical supervision, are not widely regulated in India, and carry risks including insulin resistance and potential tumor promotion if IGF-1 goes too high.
The GH–IGF-1 axis explained
Your hypothalamus releases GHRH (growth hormone-releasing hormone) which tells the pituitary to secrete GH. GH then travels to the liver and stimulates production of IGF-1 (insulin-like growth factor 1). IGF-1 is the main effector — it's what actually drives muscle growth, bone density, and tissue repair.
There's a feedback loop: when IGF-1 gets high enough, it signals the hypothalamus to reduce GHRH and increase somatostatin (which inhibits GH release). This is why exogenous GH or peptides that push IGF-1 too high can backfire — the body's natural production shuts down in response.
GH decline with age
- Peak production: Adolescence — GH levels are highest during the growth spurt
- Age 30+: GH secretion declines ~15% per decade (sometimes called "somatopause")
- Age 60+: GH output is typically 20–30% of what it was at age 25
- Sleep quality: Age-related loss of slow-wave sleep accounts for much of the decline — not just pituitary aging
This decline correlates with loss of muscle mass, increased body fat, reduced bone density, and slower recovery. Whether supplementing GH or boosting it with peptides reverses these changes safely and meaningfully in healthy adults remains debated in the literature.
When GH testing is actually useful
- Suspected GH deficiency — Fatigue, loss of muscle mass, increased central fat, low IGF-1 → your doctor orders a stimulation test
- Suspected acromegaly — Enlarged hands/feet, jaw changes, high IGF-1 → suppression test (oral glucose tolerance test) to confirm
- Monitoring peptide therapy — If you're using GH secretagogues, periodic IGF-1 checks ensure levels stay in a safe range
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