Acromegaly is a rare and severe disease caused by an increased and autonomous secretion of growth hormone (GH), thus resulting in high circulating levels of insulin-like growth factor 1 (IGF-1). Comorbidities and mortality rate are closely related to the disease duration. However, in most cases achieving biochemical control means reducing or even normalizing mortality and restoring normal life expectancy. Current treatment for acromegaly includes neurosurgery, radiotherapy and medical therapy. Transsphenoidal surgery often represents the recommended first-line treatment. First-generation somatostatin receptor ligands (SRLs) are the drug of choice in patients with persistent disease after surgery and are suggested as first-line treatment for those ineligible for surgery. However, only about half of patients treated with octreotide (or lanreotide) achieve biochemical control. Other available drugs approved for clinical use are the second-generation SRL pasireotide, the dopamine agonist cabergoline, and the GH-receptor antagonist pegvisomant. In the present paper, we revised the current literature about the management of acromegaly, aiming to highlight the most relevant and recent therapeutic strategies proposed for patients resistant to first-line medical therapy. Furthermore, we discussed the potential molecular mechanisms involved in the variable response to first-generation SRLs. Due to the availability of different medical therapies, the choice for the most appropriate drug can be currently based also on the peculiar clinical characteristics of each patient.

Context Discordant GH and IGF-1 values are frequent in acromegaly. Objective To evaluate the impact of different GH cut-offs on discordance rate. To investigate whether the mean of consecutive GH measurements impact discordance rate when matched to the last available IGF-1 value. Design Retrospective study. Setting Referral centre for pituitary diseases. Patients Ninety acromegaly patients with at least three consecutive evaluations for GH and IGF-1 using the same assay in the same laboratory (median follow-up 13 years). Interventions Multimodal treatment of acromegaly. Main outcome measures Single fasting GH (GHf) and IGF-1 (IGF-1f). Mean of three GH measurements (GHm), collected during consecutive routine patients’ evaluations. Results At last evaluation GHf values were 1.99 ± 2.79 µg/L and age-adjusted IGF-1f 0.86 ± 0.44 xULN (mean ± SD). Discordance rate using GHf was 52.2% (cut-off 1 µg/L) and 35.6% (cut-off 2.5 µg/L) (p=0.025). “High GH” discordance was more common for GHf <1.0 µg/L, while “high IGF-1” was predominant for GHf <2.5 µg/L (p<0.0001). Using GHm mitigated the impact of GH cut-offs on discordance (GHm <1.0 µg/L: 43.3%; GHm <2.5 µg/L: 38.9%; p=0.265). At ROC curve analysis, both GHf and GHm were poor predictors of IGF-1f normalization (AUC=0.611 and AUC=0.645, respectively). The prevalence of disease-related comorbidities did not significantly differ between controlled, discordant, and active disease patients. Discussion GH/IGF-1 discordance strongly depends on GH cut-offs. The use of GHm lessen the impact of GH cut-offs. Measurement of fasting GH levels (both GHf and GHm) is a poor predictor of IGF-1f normalization in our cohort.

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