Cross-sectional study to be carried out on patients with stages 3, 4 and 5 in a Nephrology outpatient clinic. Thyroid function is evaluated by measuring thyroid stimulating hormone (TSH), free thyroxine, free triiodothyronine and antithyroperoxidase antibodies (TPOAb) levels. Free Thyroxine (FT4) will be measured by liquid chromatography tandem mass spectrometry and electrochemiluminescence immunoassay in order to compare methods in this population.
The glomerular filtration rate was estimated (eGFR) by the Chronic Kidney Disease Epidemiology Collaboration formula (CKD-EPI), and the CKD stages were defined according to the Kidney Disease Improving Global Outcomes directives (KDIGO).
