Thyroid hormone status in patients with impaired kidney function.

Area of Science:

• Nephrology
• Endocrinology
• Internal Medicine

Background:

• Thyroid hormone abnormalities are frequently observed in patients with chronic kidney disease (CKD).
• The relationship between thyroid function and kidney function, especially in the context of proteinuria, requires further elucidation.

Purpose of the Study:

• To investigate the prevalence of thyroid hormone abnormalities in CKD patients.
• To examine the association between serum levels of free triiodothyronine (fT3), thyroid stimulating hormone (TSH), and free thyroxine (fT4) with kidney function and proteinuria.

Main Methods:

• A cohort of 4108 patients admitted to a Nephrology Clinic was analyzed.
• Patients were categorized by estimated glomerular filtration rate (eGFR) into normal, mild, and severe kidney impairment groups.
• Multivariate regression analysis was employed to assess correlations.

Main Results:

• The prevalence of "low-T3 syndrome" was 2.5 times higher in patients with severe kidney impairment compared to those with normal eGFR.
• Impaired kidney function was associated with lower fT4 and fT3 levels, but not TSH.
• Proteinuria showed an inverse correlation with fT4 levels across all subgroups and with fT3 levels in patients with eGFR < 60 ml/min.

Conclusions:

• Advanced CKD is associated with a significantly higher prevalence of "low-T3 syndrome".
• Both eGFR and proteinuria are strongly correlated with thyroid hormone levels in advanced CKD.
• Routine screening of thyroid profiles is recommended for all CKD patients, particularly those with proteinuria.