Improvement of thyroid hormone profile and thyrotrophin (TSH) surge alterations in hemodialysis patients on erythropoietin treatment

Background, material and methods: This study was performed in 20 patients w ith end-stage chronic renal failure (CRF) and 10 healthy volunteers, All of the patients were on regular hemodialysis treatment (RHD), 10 of whom were on recombinant human erythropoietin (rHuEPO) therapy. Hematocrit levels of the patients with CRF on rHuEPO were between 0.30 to 0.33 and not on rHuEP O were below 0.24. Baseline serum T-3, T-4, fr(3), fT(4) and TSH levels wer e measured and TRH stimulation test was performed in patients and control s ubjects. Serum TSH levels were measured hourly during the afternoon (2 to 5 p.m.) and at night (10 p.m. to 2 a.m.) to determine the nocturnal rhythm o f TSH. Results: The mean T3 in rHuEPO, not rHuEPO and control groups were 9 8.01 +/- 5.54, 70.55 +/- 7.09, 98.29 +/- 4.2 ng/dl; T-4 6.47 +/- 0.68, 6.39 +/- 0.59, 8.35 +/- 0.46 ng/dl; fT(3) 2.24 +/- 0.19, 1.52 +/- 0.24, 2.29 +/ - 0.17pg/ml and fT(4) 0.88 +/- 0.14, 0.75 +/- 0.14, 0.97 +/- 0.10 ng/dl, re spectively. These values were significantly lower in patients not on rHuEPO compared to controls (p < 0.05). In patients on rHuEPO only T4 values were lower than in the controls (p < 0.05). In patients not on rHuEPO the T3, a nd fr3 were significantly lower than the values of patients on rHuEPO treat ment (p < 0.05). Normal in 8 (80%), blunted in 1 (10%), no TSH response in I (10%) to TRH stimulation were obtained in rHuEPO group. TSH response was normal in 1 (10%), and delayed in 9 (90%) patients not on rHuEPO. The circa dian nocturnal rhythm of TSH was abnormal in 8 (90%) patients not on rHuEPO , in 2 (20%) patients on rHuEPO. As a result, CRF and RHD distorts the circ adian TSH rhythm and substantially change the thyroid hormone profile proba bly by affecting hypothalamic-pituitary-thyroid axis. Distortion of the cir cadian rhythm of TSH and TSH response to TRH points to a defect at the leve l of hypothalamus and pituitary gland. Conclusion: rHuEPO treatment has som e beneficial effects on hypothalamo-pituitary-thyroid axis in the patients on RHD.