Endocrine Abstracts

Introduction: Acromegaly is a rare disease of the pituitary gland. Both GH and IGF-1 levels are of key importance for monitoring of treatment effects in patients with acromegaly. In some patients, divergent results of measurements of these hormones are observed.

Purpose: The purpose of the study was to estimate frequency of GH and IGF-1 inconsistencies in the population of patients with acromegaly included in the Polish Register of Acromegaly Patients, and to investigate whether selected biochemical parameters can predict the possibility of GH/IGF-1 incompatibility.

Material and methods: 143 patients with acromegaly were included in the analysis.

• G1 (n=43) GH <1 µg/l and IGF-1 within the reference range for sex and age,

• G2 (n=51) GH> 1 µg/l and IGF-1 above the reference range for sex and age,

• G3 (n=15) GH> 1 µg/ml and IGF-1 within the reference values for sex and age,

• G4 (n=34) GH <1 µg/ml and IGF-1 above the reference range.

Results: The discrepancy of results of GH and IGF-1 hormonal tests in the studied population was found in 49 patients (34%). There were no statistical differences between the study groups in terms of age, disease duration, time since surgery, GH and IGF-1 levels at diagnosis, fasting glucose and HBA1C. Based on unidimensional logistic regression models, it was found that the GH/IGF-1 discrepancy was significantly associated with GH level at the time of diagnosis of acromegaly (OR = 0.98 CI95 [0.96; 0.99], P= 0.039) and with creatinine level (OR = 10.94 CI95 [1.75; 82.77], P= 0.014). The multivariate regression model showed that parameters studied: surgery, IGF-1 concentration at diagnosis, and creatinine levels, turned out to be the best combination of factors predicting the possibility of GH/IGF-1 incompatibility. The surgery to remove the pituitary adenoma and increasing concentration of creatinine increased the possibility of discrepancy (OR = 15.45 CI95 [2.24; 358.92], P= 0.023 and OR = 15.71 CI95 [1.87; 160.48], P= 0.014, respectively), while the increase in IGF-1 concentration at diagnosis reduced the possibility of GH/IGF-1 discrepancy (OR = 0.998 CI95 [0.997; 0.999], P= 0.008).

Conclusions: 1. On the basis of obtained results, the discrepancy between GH and IGF-1 hormonal determinations among the studied patients was 34%. 2. An increase in IGF-1 concentration at the time of diagnosis decreased the possibility of GH/IGF-1 discrepancy, while adenoma resection and the observed increase in creatinine level increased the risk of GH/IGF-1 discrepancy.