Endocrine Abstracts

Introduction

Hepcidin, main body iron regulator protein, decreases iron concentration available for erythropoiesis. Oppositely, excessive erythropoiesis in acromegaly patients (increased GH and IGF-1), may inhibit hepcidin production. GH stimulates bone marrow, whereas IGF-1 receptors are expressed in erythrocytes. Exogenous GH administration in healthy subjects reduced hepcidin level. The role of hepcidin in iron metabolism of acromegaly patients has not been established. This prospective, cross-sectional study evaluated for the first time the hepcidin level in relation to iron parameters in newly diagnosed acromegaly patients.

Materials&Methods

We included 25 patients (16 men and 9 women) of mean age 49 ± 17 years at the time of acromegaly diagnosis, expressed by elevated IGF-1 and GH level. Control group consisted of 25 healthy subjects matched by age and sex (CS). Applied exclusion criteria were pregnancy, breastfeeding, anaemia, haemolysis, haemorrhage, hemochromatosis, inflammation, neoplasms, kidney and liver diseases, autoimmune diseases, supplementation of iron, vitamin B12, folic acid and erythropoietin or hormonal treatment. Bioacvite form, Hepcidin-25, was measured in serum by high-sensitive ELISA (DRG Instruments GmbH, Germany). GH and IGF-1 serum concentrations were analysed by Hitachi Cobas e601 chemiluminescent analyser (Roche Diagnostics). To adjust IGF-1 to age and gender, percent over the upper limit of normal rage was used in some calculations (%IGF-1). Additionally, blood and iron parameters (complete blood count, haemoglobin, haematocrit, ferritin, iron) were evaluated.

Results

The median serum hepcidin concentration was significantly lower in acromegaly patients than in CS (9.8 vs 21.3 ng/ml, P = 0.003). Low hepcidin level in the acromegaly group was observed in both males (13 vs 23.9, P = 0.03) and females (7.6 vs 21.3, P = 0.09). Hepcidin correlated negatively with IGF-1 (P <0.05, rho = -0.44) in acromegaly patients. The positive correlation was seen between iron concentration and%IGF-1 in acromegaly male subgroup (P <0.05, rho = 0.532). Ferritin level was significantly lower (P = 0.02) in acromegaly males (94 ng/ml), than in healthy male subgroup (184 ng/ml). Red blood cell and iron parameters were within normal ranges in all subjects.

Conclusions

Acromegaly is characterized by diminished hepcidin serum concentration without concomitant iron and complete blood count abnormalities. Presumably, somatotropin axis disturbances in the course of acromegaly, may negatively impact hepcidin, which might be a mechanism aiming to increase iron availability for cells excessive replication resulting in tissue overgrowth, seen in acromegaly. This has to be proved in further studies.