Peripheral precocious puberty

Question 1

Peripheral precocious puberty investigation results

Answer 1

• The bone age is usually advanced except in hypothyroidism.
• Baseline FSH and LH concentrations are in the prepubertal range.
• GnRH (LHRH) testing reveals a relatively flat gonadotrophin response.
• Serum estradiol: very high levels may be associated with ovarian cysts or tumours

Question 2

Adrenal causes of precocious puberty investigations

Answer 2

• Measurement of serum 17-hydroxyprogesterone and other androgens (DHEA) and DHEAS is indicated
• Serum 17-hydroxyprogesterone levels are elevated in adrenal enzymatic defects (21-hydroxylase deficiency and occasionally with adrenal tumours
• Serum DHEAS is produced in the adrenals and is a marker of androgen-producing adrenal tumours and adrenal enzymatic defects
• A urinary steroid profile and adrenocorticotrophin stimulation test are useful in identifying adrenal steroid synthesis defects. Urinary 17-ketosteroid levels can be very high in girls with adrenal tumours.

Question 3

Other investigation results in peripheral precocious puberty

Answer 3

• TFTs show low free T4 and markedly elevated TSH levels secondary to severe primary hypothyroidism.
• Serum prolactin levels may be increased in some girls with McCune–Albright syndrome and chronic hypothyroidism (probably because of enhanced thyrotropin-releasing hormone secretion, stimulating prolactin release)
• Pelvic ultrasound and adrenal CT should also be considered to look for a gonadal or adrenal tumour.
• In girls with McCune–Albright syndrome a skeletal survey and bone scan may identify the characteristic bony abnormalities of polyostotic fibrous dysplasia.