[The influence of recombinant human erythropoietin (rHu-EPO) on circadian rhythm of prolactin secretion in patients with chronic renal failure treated with hemodialysis].

Patients with chronic renal failure (CRF) have high serum prolactin level. In healthy subjects the circadian rhythm of prolactin secretion is well known. This study aimed to investigate, if the circadian rhythm of prolactin was maintained in patients with CRF treated with haemodialysis despite hyperprolactinaemia, and how the treatment with erythropoietin influenced the circadian rhythm of prolactin. Serum prolactin was determined four times a day at 6:00, 12:00, 18:00, 24:00 in 30 patients with CRF and in 15 healthy subjects. In the patients with CRF this investigation was both done on the day with haemodialysis and on the day without haemodialysis. The patients were divided into two groups: the first one included patients treated with erythropoietin and the second one included patients not treated with erythropoietin. The results of the investigation were analysed using the Cosinor test. Serum concentration of hormones was determined by LIA. It was shown that the circadian rhythm of prolactin was maintained in patients with CRF both on the day with and without haemodialysis. Both in patients with CRF and in healthy subjects the circadian rhythm indicated the highest serum concentration of prolactin in the night hours i.e. 22:30-1:00. In patients treated with erythropoietin a significantly lower average day concentration of prolactin was observed in comparison with patients not treated with erythropoietin.