The Effect of Metformin Treatment on Disease Control in Patients with Acromegaly

BACKGROUND

The increase in portal insulin levels has been shown to upregulate growth hormone receptor expression in the liver, leading to increased insulin-like growth hormone- 1 levels. Metformin inhibits hepatic gluconeogenesis and reduces fasting insulin.

OBJECTIVE

We evaluated the effect of metformin treatment in patients with acromegaly on growth hormone, insulin-like growth hormone-1, and pituitary adenoma size.

METHODS

Patients who were followed up with the diagnosis of acromegaly in Istanbul University- Cerrahpaşa, Cerrahpaşa Medical Faculty were evaluated. The patients were divided into three groups after pituitary adenectomy as those who received somatostatin receptor ligand and metformin treatment (group A), somatostatin receptor ligand treatment only (group B), and those who received metformin treatment only (group C). Groups A and B were compared with each other, and patients in group C were compared among themselves.

RESULTS

While the median insulin-like growth factor-1 level decreased to 170 ng/ml in Group A after the treatment, the median insulin-like growth factor-1 level decreased to 229 ng/ml in Group B, and a statistically significant difference was found between the two groups (p =0.020). There was no significant difference in post-treatment growth hormone levels and residual adenoma sizes between groups A and B (p >0.005). In group C, there was no significant difference in growth hormone values pre-and post-metformin treatment (p =0.078); however, the median insulin-like growth factor-1 level decreased from 205 ng/ml to 168 ng/ml during metformin treatment and was found to be statistically significant (p =0.027).

CONCLUSION

Due to the effect of metformin treatment on insulin-like growth factor-1 values in patients with acromegaly, it can be used in disease control, as well as diabetes treatment.

Patients with acromegaly might not be at higher risk for dopamine agonist-induced impulse control disorders than those with prolactinomas

OBJECTIVE

To evaluate the prevalence of impulse control disorders (ICD) and psychiatric symptoms in patients with acromegaly receiving dopamine agonists (DA) in comparison with those with prolactinoma, nonfunctioning pituitary adenomas (NFA), and healthy controls (HC).

DESIGN

Forty patients with acromegaly, 40 with prolactinoma, 38 with NFA, and 32 HCs were included. All patients and controls were evaluated using the revised version of the Minnesota Impulsive Disorders Interview (MIDI-R), Symptom Check List (SCL-90-R) questionnaire, Barratt Impulsiveness Scale (BIS-11), Beck Depression Inventory (BDI), and Beck Anxiety Inventory (BAI).

RESULTS

We detected ICD associated with DAs in two patients with acromegaly (5%) and three patients (7.5%) with prolactinoma. All patients' symptoms resolved after discontinuation of the drug. While the mean DA dose was higher in patients with acromegaly than prolactinomas (p < 0.05), no difference was detected in terms of ICD prevalence between two groups (p > 0.05). SCL-90 depression and interpersonal sensitivity subscale positivity was higher in patients with NFA than HCs. Patients with prolactinoma had higher obsession and interpersonal sensitivity positivity and those with NFA had higher somatization, interpersonal sensitivity, and depression positivity as compared to patients with acromegaly (p < 0.05 for all).

CONCLUSIONS

Although DA dose was significantly higher in patients with acromegaly, there was no significant difference in the prevalence of DA-related ICD. The higher prevalence of positive screening in SCL-90 in patients with NFA in comparison to HCs supports the hypothesis that the presence of a pituitary adenoma per se might cause significant psychiatric symptoms.

MON-293 The Prevalence of Impulse Control Disorders in Patients with Acromegaly and Prolactinomas Treated with Dopamine Agonists

Objective: There is emerging evidence linking dopamine agonist (DA) use with the development of impulse control disorders (ICD) in patients with prolactinomas. On the other hand, no data exist whether DA use in acromegaly is associated with ICD. We aimed to evaluate the prevalence of ICD, psychiatric symptoms in patients with prolactinoma and acromegaly receiving DA in comparison to those with nonfunctioning pituitary adenomas (NFA) and healthy controls (HC).

Material and Method: Forty patients with prolactinoma, 40 patients with acromegaly, 38 patients with NFA and 32 HC were included in this study. All patients and controls included in the study were evaluated with revised version of Minnesota Impulsive Disorders Interview (MIDI-R), Symptom Check List (SCL-90-R) questionnaire, Barratt Impulsiveness Scale (BIS-11), Beck Depression Inventory (BDI), and Beck Anxiety Inventory (BAI). All of the patients with prolactinoma and acromegaly had been receiving cabergoline therapy but patients with NFA had not been receiving cabergoline therapy at the time of the study.

Results: We detected DA associated with ICD in 3 patients (7.5%) with prolactinoma, and 2 patients with acromegaly (5%). All patients’ symptoms resolved after either discontinuation of the drug or surgical intervention. There was no significant difference between patients with acromegaly and prolactinoma in terms of ICD prevalence. On the other hand, ICD was not detected in non functional adenoma and HC. There was no correlation between BIS-11 scores and total dose, mean monthly dose and duration of DA.

According to SCL-90-R, obsession and interpersonal sensitivity positivity was significantly higher in patients with prolactinoma than acromegaly (p: 0.040, p:0.010, respectively). There was no significant difference between the groups in terms of BAI, BDI and BIS-11’s subscales and total scores (p> 0.005). Scl-90 somatization and depression positivity was significantly higher in patients with NFA than acromegaly (p: 0.043, p: 0.024 respectively). Likewise, scl-90 depression, interpersonal sensitivity and additional items subscale positivity was significantly higher in patients with NFA than HC (p: 0.005, p: 0.045, p: 0.045 respectively).

Conclusion: Although DA dose was significantly higher in patients with acromegaly compared to patients with prolactinoma, there was no significant difference in the prevalence of DA -related ICD. We have showed that there was no association between BIS-11 scores and total DA dose, mean monthly DA dose and duration of DA treatment. The higher prevalence of depression, interpersonal sensitivity in patients with NFA in comparison to HC supports the hypothesis the presence of a pituitary adenoma per se might cause a large psychiatric symptom burden.