Most individuals fall between: 150–250 ng/mL
Common causes of LOW IGF-1 (guideline-listed)
A. GH-related
Adult Growth Hormone Deficiency (AGHD)
Hypothalamic–pituitary disease
Post-pituitary surgery or radiotherapy
B. Non-GH causes (important per guidelines)
Malnutrition / low protein intake
Chronic
liver disease (very important – IGF-1 is liver-derived)
Poorly controlled
diabetes mellitus
Hypothyroidism
Chronic
kidney disease
Chronic inflammatory/systemic illness
C. Physiological / functional
Obesity (GH resistance)
Severe stress
Aging
Poor sleep