Understanding Lab Tests for Delayed Puberty in Girls
Written by Private MD Labs Medical Writing Team • Last Updated: September 8, 2025
Delayed puberty in girls is typically defined as the absence of breast development by age 13 or lack of menstruation by age 16. While there isn't a single blood test that directly diagnoses delayed puberty, laboratory testing is fundamental for evaluating the underlying hormonal and growth factors that influence pubertal development.
Recommended Test
Insulin-Like Growth Factor I (IGF-I, LC/MS)
This test measures IGF-1 levels, which are closely linked to growth hormone activity and typically increase during normal puberty. Low IGF-1 levels or negative Z-scores in girls can indicate delayed pubertal development, helping healthcare providers assess whether growth hormone deficiency or other factors may be contributing to the delay.
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Why Blood Testing is Important for Delayed Puberty
Blood tests help healthcare providers assess growth hormone function, nutritional status, and other factors that may contribute to delayed pubertal development. These tests provide valuable insights into whether the delay is due to constitutional factors, underlying medical conditions, or hormonal imbalances that may require treatment.
Understanding Your Results
IGF-1 levels are often reported as Z-scores, which compare an individual's levels to age and gender-matched peers. Results should always be interpreted by a healthcare provider who can consider the complete clinical picture, including physical examination findings, growth patterns, and family history.
Important Considerations
The information here is for educational purposes only and is not a substitute for professional medical advice. Always consult with a healthcare provider for diagnosis and treatment. Additional hormone tests and imaging studies may also be recommended as part of a comprehensive evaluation.
