Clinical and metabolic characteristics of acromegalic patients with high IGF1/normal GH levels during somatostatin analog treatment

Context: Divergence between GH and IGF1 values are often reported in treated acromegalic patients, but the mechanisms of this discrepancy have not been completely explored. Objective: To evaluate the frequency of divergence between GH and IGF1 values and identify the role of clinical and metabolic factors in treated patients with acromegaly, according to the latest criteria of Cure published in July 2010. Design: Retrospective study of patients' records between October 2002 and March 2008. Patients were grouped according to their mean GH and IGF1 values as 'controlled' (normal GH and IGF1), 'divergent' (high IGF1 and normal GH) and 'uncontrolled' (high GH and IGF1), and compared with respect to their clinical characteristics and metabolic markers. Results: Patients (n=104) were grouped as 'controlled' (n=20), 'divergent' (n=43) and 'uncontrolled' (n=41). More patients in the divergent group (93%) and uncontrolled group (98%) were treated with somatostatin analogs than in the controlled group (65%; P=0.001 for the comparison of the three groups). Patients in the divergent group had higher fasting blood glucose (0.94 g/l (interquartile range: 0.83-1.17)) and systolic blood pressure (130 mmHg (120-140) compared with the controlled group (0.84 g/l (0.80-0.92); P=0.017) and 120 mmHg (interquartile range: 110-130; P=0.029). In patients with divergent IGF1/GH levels, fasting glucose and GH were both strongly associated with IGF1. Conclusion: Totally 41% of treated acromegalic patients had a high IGF1 and normal GH level. In these divergent patients treated with somatostatin analogs, these clinical and metabolic parameters might either play a causal role or be a marker for disease activity.