Thyroid function has been assessed in 36 clinically euthyroid patients
undergoing regular haemodialysis. The influence of erythropoietin adm
inistration on the thyroid function tests has been determined. Thyroid
-stimulating hormone (TSH) has been found to be elevated in 8% of the
patients. Free tri-iodothyronine was below the normal range in 67% of
the population. Free tyroxine (FT4) was low in 67% of the patients whe
n tested by an analogue method. FT4 tested by a 2-stage method in a su
bgroup of 22 patients was abnormally low in only 23% of the patients.
Erythropoietin did not seem to improve these thyroid abnormalities des
pite a partial correction of the anaemia. A rise in FT4 was also obser
ved after haemodialysis without a concomitant change in TSH concentrat
ion. This FT4 elevation was attributed to the effect of heparin.