Endocrine Abstracts

Acromegaly control/remission is defined by stringent criteria: normal age-/sex-adjusted IGF1 and random GH (GHr) <1 ng/ml or a GH nadir (GHn) during oral glucose tolerance test (OGTT) of <0.4 ng/ml. However discordances between GH and IGF1 have been recorded in about 30% of patients. We retrospectively analyzed the evolution in patients with acromegaly and discordant GH–IGF1 levels while being treated with somatostatin analogs (SSA) and/or cabergoline (CAB).

Out of 22 patients with acromegaly treated with SSA and/or CAB in 2011–2015, seven patients (all women, mean age at diagnosis 48 years, range 29–63 years) had discordant normal GH and elevated IGF1 levels (31.8%). One patient had also a transient increased GHr with normal IGF1 during follow-up. All had macroadenomas, 42% were obese, 42% overweight. One patient had diabetes mellitus and four had impaired fasting glucose. Six patients were treated with SSA (two also+CAB), one only with CAB, five had previous pituitary surgery, and two had also radiotherapy. The patients had a mean number of 6.7 evaluations of IGF1 and GH (4–8) during a mean follow-up of 34.5 months (25–42). Mean elevated IGF1 was 1.43×upper limit of normal (1.08–1.83).

A SSA dosage increase and/or CAB addition in six patients normalized both GH and IGF1 in three patients (50%), one patient was not controlled on both GH and IGF1 and in two patients the discordance persisted. In one of these latter patients the tumor had a >50% decrease in size; in all the others the tumors had no or up to 25% shrinkage. No significant alterations of glycemia or blood pressure have been recorded.

Conclusion: Management of acromegalic patients with discordant GH–IGF1 values needs to be individualized. Long-term studies on morbidity and mortality in these patients are needed.