Association Between Chronic Kidney Disease and Subclinical Hypothyroidism Categorized by Hypertension Status

Background/Objectives: Subclinical hypothyroidism (SCH) has been reported to be associated with chronic kidney disease (CKD). Anti–thyroid peroxidase antibody (TPO-Ab) positivity, a known cause of autoimmune thyroid disease, has been reported to be positively associated with SCH with hypertension, but not with SCH without hypertension. Therefore, hypertension status might indicate latent thyroid damage among individuals with SCH. This distinction suggests that categorizing SCH by hypertension status could be useful for evaluating its association with CKD. Methods: A cross-sectional study of 1479 Japanese aged 40–69 years, all of whom had thyroid hormone levels (free triiodothyronine and free thyroxine) within the normal range, was conducted to evaluate the association between CKD and SCH categorized by hypertension status. Results: No significant association between SCH without hypertension and CKD was observed. However, a significant positive association between SCH with hypertension and CKD was identified. The potential confounders-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were 0.96 (0.39, 2.38) for SCH without hypertension and 2.76 (1.37, 5.59) for SCH with hypertension. Conclusions: Although further investigation is warranted, categorizing SCH by hypertension status may be useful for understanding the association between SCH and CKD. These findings may help clarify the biological significance of SCH in the development of CKD.