Central precocious puberty

Question 1

CPP investigation results

Answer 1

• The bone age is advanced, often by more than 2 years.
• Baseline serum gonadotrophins may be raised.
• Estradiol levels are variable and not very reliable in the diagnosis of precocious puberty.
• Elevated prolactin levels are rarely seen in girls with CPP

Question 2

CPP imaging results

Answer 2

• A uterine volume >2 ml or length >34 mm
• A pear-shaped uterus and endometrial thickening (endometrial echo)
• MRI of the brain (or CT if MRI is unavailable) is advised in all girls with progressive CPP to exclude a central nervous system lesion

Question 3

The GnRH stimulation test in CPP

Answer 3

• The gold standard test for CPP
• It is performed by measuring FSH and LH levels sequentially after administering a GnRH analogue bolus
• In healthy pubertal children the LH response exceeds the FSH response
• In prepubertal children and in thelarche variant, the FSH response exceeds the LH response
• In cases of CPP, GnRH stimulation shows a pubertal response with LH:FSH ratio >1. Peak LH levels vary, depending on the specific assay used, but values of >8 iu/l are usually considered diagnostic of CPP