Targeting either GH or IGF-I during somatostatin analogue treatment in patients with acromegaly: a randomized multicentre study.

Context: Discordant GH and IGF-I values are frequent in acromegaly. The clinical significance and its dependence on treatment modality and of glucose-suppressed GH (GH) measurements remain uncertain.

Objective: To evaluate the effects of targeting IGF-I GH during somatostatin analogue (SA) treatment.

Patients And Methods: 84 patients with controlled acromegaly after surgery ( = 23) or SA ( = 61) underwent a GH profile including an OGTT, at baseline and after 12 months. SA patients were randomized to monitoring according to either IGF-I ( = 33) or GH ( = 28). SA dose escalation was allowed at baseline and 6 months.

Main Outcome Measures: GH and IGF-I at baseline and 12 months, and disease-specific Quality of Life (QoL).

Results: IGF-I and fasting GH levels were comparable between the surgery and the SA group, whereas GH (µg/L) was lower in the surgery group (GH 0.7 ± 0.1 vs 0.3 ± 0.1,  < 0.01). SA dose increase was performed in 20 patients in the GH group and in 8 patients in the IGF-I group ( = 0.02), which increased the number of concordantly controlled patients ( = 0.01). QoL was only mildly affected at baseline in all groups and did not changed consistently during the study.

Conclusion: (1) Discordant values in terms of high GH levels are prevalent in SA patients and more so if applying glucose-suppressed GH; (2) targeting discordant levels of either GH or IGF-I translates into SA dose increase and improved biochemical control; (3) even though QoL was not improved in this study, we suggest biochemical assessment of disease activity to include glucose-suppressed GH also in SA patients.