A GnRH agonist (eg, leuprolide) is used as continuous therapy to treat central precocious puberty, not pubertal delay, by inhibiting gonadotropin release. It can also be used as pulsatile therapy in the treatment of functional hypothalamic amenorrhea, but this condition is typically due to insufficient caloric intake to meet nutritional needs (eg, anorexia nervosa), which is unlikely in this patient with a normal BMI.
Evaluation includes a thyroid-stimulating hormone level to evaluate for hypothyroidism and a pelvic ultrasound to confirm the presence of a uterus and ovaries. MRI of the brain may be indicated in a patient who also has galactorrhea and an elevated prolactin level, a presentation suggestive of a prolactinoma.
MRI of the head is indicated in patients with a low or normal FSH, high prolactin, or visual field defects to evaluate hypothalamic and pituitary causes (eg, sellar mass).