Why carry out this study?

Chronic kidney disease (CKD), a common and debilitating condition tied to considerable economic burden, can be comorbid with subclinical hypothyroidism [SCH; i.e., elevated serum thyroid-stimulating hormone (TSH) despite normal free thyroxine levels].

Although studies outside the US have shown that levothyroxine replacement therapy in CKD + SCH patients is associated with improvements in renal function, US evidence is lacking.

This study evaluated renal outcomes and hospital length of stay (LOS) in a CKD + SCH US veteran population treated with levothyroxine.

What was learned from the study?

Although there was no significant difference between levothyroxine-treated and untreated CKD + SCH patients over 24 months in clinical outcomes [estimated glomerular filtration rate (eGFR) measures; CKD progression], significantly lower LOS for CKD-related reasons and numerically lower all-cause LOS demonstrated a possible economic benefit for levothyroxine.

Although not statistically significant, CKD + SCH patients who were levothyroxine-treated had numerically lower proportions of progression to higher CKD stages at 12, 18, and 24 months; in a small subset with baseline TSH > 10 mIU/L (n = 25: 15 treated, 10 untreated), a numerically lower proportion of treated patients had CKD progression to higher CKD stages compared with untreated patients.

Prospective trials or larger retrospective analyses of sufficient sample size may further elucidate these retrospective database analysis findings.