Elevated Prolactin Non-Reponsive to Cabergoline


Question

I'm an argentine endocinologIst. I have a patient 18 years old young woman. She had her first menstruation at 14 y/o and was regular for 2 years. Then she started a secondary amenorrhea with PRL over 120 ng/ml. She consulted me on September 2005. I didn't find galactorrhea, the weight was normal (BMI 24), the genetic study was normal, the MRI in September showed a normal pituitary gland, except for a very little image suspicious, but not clear. The fractionated PRL was elevated in all the fragments. We start with cabergoline in crescent dose. At the present time, with 4mg of cabergoline, the MRI shows a decrease of pitutary size, PRLis 100 ng/ml and she is still amenorrheic as the only symptom. She shows some sign of emotional stress but refuses psychotherapy. How do I best manage this patient? Thank you for your attention and your advice. Forgive my poor english. Susana Nemas, MD. La Plata. Rep Argentina

Response

Thank you. This is a difficult problem. The initial prolactin with only a suspicion of a microprolactinoma raises the possibility of macroprolactin

interference in the assay, but I take your point on the 'prolactin fractions' to have excluded this possibility. If not, retesting the current prolactin after polyethylene glycol precipitation may reveal whether this all all monomeric prolactin. If it is, then the dose of cabergoline is already very high, so you could switch to an alternative drug such as quinagolide, although my experiece is that there is usually cross-resistance to all drugs. If the only problem is lack of menstruation then simply starting the oral contaceptive pill will provide regular menses and avoid the risk of osteoporosis, but regular rescanning is mandatory. Alternatively, a new high quality MRI should be discussed with an experienced transsphenoidal surgeon with a view to microadenomectomy. Ashley Grossman, MD