Thyroid hormone transport is disturbed in erythrocytes from patients with chronic renal failure on hemodialysis

Aims: To now, there are no studies reporting whether thyroid hormones (THs) transport play a role in thyroid hormone dysfunction observed in chronic renal failure (CRF). Therefore, the aim of this study was to investigate the transport of THs in erythrocytes from patients with CRF on hemodialysis (HD). Methods: [I-125]-L-triiodothyronine ([I-125]T-3) and [I-125] -L-thyroxine ([I-125]T-4) erythrocytes uptake was measured at 1 min and 5 min. To study L-triiodothyronine (LT3) and L-thyroxine (LT4) efflux from erythrocytes, we preloaded the cells during 180 min with [I-125]T-3 or [I-125]T-4 and measured their [I-125]T-3 or [I-125]T-4 efflux during 60 min. Results: [I-125]T-3 uptake in erythrocytes from uremic patients pre-HD was higher than control subjects by 50% at 1 min and by 55% at 5 min. However, [I-125]T-4 uptake in erythrocytes from uremic patients was significantly lower at 1 min (88%) and at 5 min (63%). LT3 efflux rate was lower and LT4 efflux was significantly higher than in control subjects. After 60-min of efflux, LT3 remained in erythrocytes was 80% higher and LT4 was 57% lower than in normal individuals. Neither [I-125]T-3 and [I-125]T-4 uptake, nor efflux rates were changed by hemodialysis. Conclusion: Despite the fact that uremic patients on hemodialysis show low serum levels of LT3, changes in LT3 influx and efflux could act as a compensatory mechanism that neutralize thyroid hormone dysfunction in order to maintain the euthyroid state.