A case of macroprolactinoma and elevated insulin-like growth factor-I in a young boy

We report a case of a 10-y-old boy who presented with persistent headache and was found to have a giant prolactinoma. Laboratory evaluation revealed markedly elevated prolactin (PRL) level, thyroid-stimulating hormone (TSH) deficiency, and elevated insulin-like growth factor-I (IGF-I). He had normal random growth hormone (GH) but non-suppressible GH during oral glucose tolerance test (OGTT). Cabergoline treatment was initiated and was well tolerated. Therapy successfully reduced PRL levels, normalized IGF-I levels, and reduced tumor size. Conclusion: Our patient presented with a GH-PRL-secreting tumor. Dopamine agonists are recommended as the treatment of choice for prolactinomas. However, there should be careful attention to GH status when treating GH-PRL-secreting tumor with dopamine agonists alone. IGF-I levels should be followed in all patients with prolactinoma, even in those with normal basal GH concentrations, because of the possibility of GH co-secretion.