Precocious Puberty


I have an 18 month old Caucasian boy presenting with 8cm penis, 8ml testes, advanced bone age of 4.5 yrs, LH stimmed to 35, high FT4 of 2.5, normal TSH, ACTH baseline 44, cortisol 7.5 random. MRI normal. Growth hormone 10.5, IGF-1 470 (very high for him), IGF-BP3 3.2. What does he have?

How do I proceed? Can you please send reply to

Thank you, Sachin Bendre MD


your patient looks like he has gonadotropin-dependent (stimulated LH 25!) precocious puberty, and I assume his testosterone levels are in the pubertal range. For the differential diagnosis, the head MRI ruled out all congenital anomalies and tumors, so we are left with the forms secondary to chronic exposure to sex steroids. I would measure baseline 17OHP levels to rule out congenital adrenal hyperplasia, and repeat TSH and FT4 (normal TSH with high FT4 is odd). The GH and IGFI, and IGFBP3 levels are consistent with the stage of pubertal development. Regardless of the cause of his precocious puberty, he needs to be treated with GnRH analogues.I look forward to hearing more about your patient. Lucia Ghizzoni, M.D., Ph.D