Insulin-like Growth Factor 1

Hormones marker

IGF-1

Insulin-like Growth Factor 1

Category: Hormones
Unit: nmol/L

Growth factor produced primarily by the liver in response to growth hormone (GH). Reflects overall GH secretion and mediates many of GH's anabolic effects. Age- and sex-specific reference ranges apply.

PED Notes

CRITICAL marker for GH use monitoring. Exogenous GH directly elevates IGF-1 — the primary way to confirm GH is working and dose-response. Supraphysiological IGF-1 (>1.5x upper limit) indicates high GH dosing and increases risk of insulin resistance, soft tissue growth, and long-term cancer risk. AAS alone do not significantly affect IGF-1. Insulin co-administration with GH further amplifies IGF-1 levels. Target for health-conscious GH use: upper-normal range (25-35 nmol/L). Recheck 4-6 weeks after dose changes. Fasting state and time since last GH injection affect levels.

When high

When elevated on exogenous GH (dose management):

  • Target range for health-conscious GH use: 25-35 nmol/L (upper-normal)
  • IGF-1 >40 nmol/L: consider reducing GH dose by 0.5-1 IU/day
  • IGF-1 >50 nmol/L: reduce GH dose immediately -- significantly elevated cancer and metabolic risk
  • Recheck IGF-1 4-6 weeks after any GH dose change (takes time to stabilise)
  • Blood draw timing: ideally 12-24h after last GH injection for stable reading; avoid testing within 4h of injection

Risks of chronically high IGF-1 (>1.5x upper limit):

  • Insulin resistance and impaired glucose tolerance (synergistic with GH)
  • Acromegalic features: soft tissue growth (hands, feet, jaw, nose, internal organs)
  • Increased cancer risk (IGF-1 is a potent growth signal -- promotes cell proliferation)
  • Cardiomegaly (heart enlargement) with prolonged supraphysiological levels
  • Visceral organ growth (intestinal, cardiac) -- contributes to "GH gut" at high doses

GH dose guidelines by goal:

  • Anti-ageing/recovery: 1-2 IU/day (IGF-1 typically stays within normal range)
  • Body composition/fat loss: 2-4 IU/day (IGF-1 upper-normal to mildly elevated)
  • Bodybuilding/muscle growth: 4-8+ IU/day (IGF-1 often significantly elevated -- monitor closely)

Supplements/Lifestyle (to manage elevated IGF-1 side effects):

  • Berberine -- 500mg 2-3x/day (improves insulin sensitivity, may modestly reduce IGF-1)
  • Metformin -- 500-1000mg/day (addresses GH-induced insulin resistance; may reduce IGF-1 slightly)
  • Monitor fasting glucose and HbA1c alongside IGF-1
  • If fasting glucose >5.5 mmol/L on GH, reduce dose or add Berberine/Metformin

When low

When IGF-1 is LOW (off GH):

  • Low IGF-1 off exogenous GH may indicate: poor nutrition, liver dysfunction (IGF-1 is hepatic), growth hormone deficiency, or chronic illness
  • Ensure adequate protein intake (IGF-1 production requires amino acid substrate)
  • Optimise sleep (GH pulses occur during deep sleep)
  • Address any liver dysfunction (liver produces >75% of circulating IGF-1)

Pharmacological options (raising low IGF-1 without exogenous HGH):

  • Sermorelin -- 200-300mcg subQ before bed; GHRH analogue, restores natural pulsatile GH/IGF-1 release; mild effect, no HPTA shutdown; cheaper and safer than rHGH for modest IGF-1 elevation
  • CJC-1295 (no DAC) + Ipamorelin -- 100mcg + 100mcg subQ 2-3x/day; GHRH + GHRP combination; produces stronger IGF-1 rise without the acromegaly risk of exogenous GH; gold-standard peptide stack
  • Tesamorelin -- 1-2mg subQ daily; FDA-approved GHRH analogue; raises IGF-1 by 30-50% with proven visceral fat reduction; higher cost
  • MK-677 (Ibutamoren) -- 10-25mg/day oral; ghrelin mimetic; raises IGF-1 substantially via increased GH pulse amplitude; warn re: insulin resistance, water retention, increased appetite, and possible cortisol elevation
  • Recombinant HGH (somatropin) -- 1-2 IU/day; most direct intervention; physician-prescribed; reserve for confirmed adult GH deficiency or when peptide approaches are insufficient
  • All require physician oversight and IGF-1 recheck at 4-6 weeks; never push IGF-1 above 35 nmol/L without close metabolic monitoring (fasting glucose, HbA1c)

History Chart

Reading History

Frequently Asked Questions

Reference Ranges

Standard Range

11 - 31 nmol/L

VitalMetrics Range

11 - 45 nmol/L

Statistics