The impact of long-term hemodialysis on pituitary-adrenocortical function

The activity of the hypothalamic-pituitary-adrenal axis in hemodialyzed (HD) patients has been investigated, with conflicting results. Different results are reported concerning both basal ACTH and cortisol concentration and the responses to different stimulating agents, in chronic hemodialyzed patients. The present study was performed in order to assess whether the length of the hemodialytic treatment may affect the pituitary and adrenocortical response to stimulation with ovine CRH (oCRH) and with exogenous ACTH in a group of patients on chronic HD for more than 10 years. Ten uremic patients (aged 3871, 6 males and 4 females) on chronic hemodialysis for at least 10 years and 7 healthy subjects matched for age and sex were studied. The patients were tested on the day preceding dialysis session. Each subject received on different non-consecutive days oCRH (100 μg i.v. in bolus) and ACTH (Synacthen 0.25 mg i.v. in bolus), and blood samples were obtained at appropriate intervals. Basal ACTH and cortisol levels of HD patients were in the upper limit of normal range (ACTH 39.21 ± 11.11 pg/mL in HD patients vs. 26.88 ± 14.12 pg/mL in controls; cortisol 19.96 ± 5.07 in HD patients rs. 12.66 ± 4.44 in controls); however, the means were not significantly different compared with controls. Following oCRH administration a net increase of ACTH and cortisol was observed in every patient tested (ACTH peak 83.81 ±28.49 in HD vs. 78.73 ± 22.87 pg/mL in controls; cortisol peak 30.73 ± 19.31 in HD vs. 20.05 ± 3.19 μg/dL in controls). Comparing the ACTH and cortisol responses to oCRH obtained in HD pts and in controls, a mild delay in the maximum response peak of ACTH (peak at 60 min vs. 30 min) and a prolonged cortisol dismission was observed. Exogenous A CTH administration elicited a normal cortisol response in both HD patients and control groups. In conclusion, our results show that the responsiveness of the pituitary-adrenal axis is maintained in uremic patients, even after more than 10 years of chronic hemodialysis; the delayed ACTH response to oCRH might be considered a further manifestation of the disordered hypothalamic regulation described in uremia and/or it is probably due to a maladaptative response to chronic stress.