Delayed puberty in girls is the absence of breast development by age 13 or lack of menstruation by age 16. It is caused by constitutional growth delay, hormonal imbalances including growth hormone deficiency, chronic medical conditions, or inadequate nutrition. The Insulin-Like Growth Factor I (IGF-I) test is the most important blood test for diagnosis because it measures growth hormone activity that drives pubertal development.
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Delayed puberty in girls is caused by constitutional growth delay (a normal variation where puberty starts later), growth hormone deficiency, chronic illnesses like celiac disease or inflammatory bowel disease, excessive athletic training, eating disorders, or genetic conditions affecting the ovaries or pituitary gland. Nutritional deficiencies and extremely low body weight can also delay the hormonal signals that trigger breast development and menstruation. In many cases, delayed puberty runs in families and girls eventually develop normally without treatment.
The Insulin-Like Growth Factor I (IGF-I) test is the most important blood test for delayed puberty in girls because it measures IGF-1 levels that reflect growth hormone activity, which normally increases during puberty. Low IGF-1 levels or negative Z-scores compared to age-matched peers can indicate growth hormone deficiency or other factors delaying development. Healthcare providers may also order additional hormone tests including luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol, and thyroid function tests to evaluate the complete hormonal picture. The IGF-1 test provides crucial information about whether the delay is related to growth hormone function or requires further evaluation.
You should get tested if you are 13 years old or older without any breast development, have not started your period by age 16, have stopped growing or are significantly shorter than your peers, or have developed some puberty signs but they have not progressed for more than a year. Testing is also important if you have a family history of delayed puberty, chronic health conditions, or symptoms like excessive fatigue, weight loss, or changes in appetite. Early evaluation helps identify whether the delay is a normal variation or requires treatment to support healthy development.
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What this means
Your IGF-1 levels are below the optimal range for your age group. This may explain symptoms like fatigue, difficulty building muscle, slower recovery after workouts, or decreased vitality. Low IGF-1 can indicate reduced growth hormone activity or inadequate nutrition, both of which can impact your energy, metabolism, and body composition.
Recommended actions
Incorporate regular resistance training and high-intensity interval workouts to stimulate growth hormone production
Prioritize 7-9 hours of quality sleep each night, especially deep sleep when growth hormone is released
Ensure adequate protein intake from quality sources like lean meats, fish, eggs, and dairy products
Consider retesting in 3-6 months after implementing lifestyle changes to track improvements
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