Childhood macroprolactinomas amenable to dopamine agonist treatment

By Eleanor McDermid, Senior medwireNews Reporter

Dopamine agonist (DA) treatment normalises prolactin levels in about three-quarters of children with macroprolactinomas, show findings from a large series.

“These results confirm that DA therapy is as effective at this young age as in adulthood”, say Philippe Chanson (Hôpital de Bicêtre, Paris, France) and study co-authors.

This makes DAs “the first-choice treatment for this young population”, they write in The Journal of Clinical Endocrinology & Metabolism.

The 77 patients in the study were diagnosed in three French specialist centres before the age of 20 years. There was a predominance of girls, at 51 versus 26 boys, and almost all the girls presented with amenorrhea – primary in 43% and secondary in 53%.

Indeed, pubertal disorders were the feature that led to the discovery of the adenoma in 49% of the patients overall. They were diagnosed at an average age of 16.1 years, but the researchers say it is “conceivable” that macroprolactinomas develop earlier in life “but are only diagnosed because of their effect on puberty”.

Other revealing symptoms were visual problems and growth retardation, each present in 24% of patients, and weight gain was also a reason for seeking medical advice in 23% of children.

Girls and boys differed in their presenting features; pubertal issues were more common in boys, at 61% versus 43% in girls, as were visual problems, at 46% versus 14%. Indeed, the two youngest boys, who were aged 4.5 and 10 years at diagnosis, were blind in one eye.

The team attributes this gender difference to the generally larger tumour size in boys, which was an average of 33 mm, compared with 19 mm in girls. Boys’ tumours were more often invasive than girls’ tumours, at 70% versus 38%.

With the exception of one patient who underwent immediate curative surgery, all of the patients received DA therapy, 68 as first-line treatment. This led to normalisation of prolactin levels in 74% of patients, from an initial average of 7168 ng/mL in boys and 1433 ng/mL in girls (normal value <150 μg/L) , and to tumour shrinkage in 76% of 74 assessed patients.

Patients with DA-resistant macroprolactinomas tended to have larger tumours and higher prolactin levels than those with DA-sensitive tumours, these two variables being closely associated with each other. By contrast, the presence of a MEN1 mutation (in three children) was significantly and independently related to DA resistance.

Most children with persistently raised prolactin levels after initial DA treatment achieved normal levels after a range of measures including surgery, radiotherapy, increased DA dose and replacement therapy for gonadotropic insufficiency.

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