The association between renin and thyroid-related biomarkers with clinical characteristics and outcomes in hyperthyroid patients

Objective There is crosstalk between the thyroid hormone and the renin-angiotensin-aldosterone system, but the clinical application is lacking. Our study aimed to verify the correlation between renin and other thyroid-related biomarkers and their association with treatment prognosis. Methods This retrospective study recruited eighty consecutive patients treated for hyperthyroidism in a medical center between 2021 and 2023. Among participants, 53 were newly diagnosed, and 27 were recurrent cases. Laboratory measurements, including renin, aldosterone, and other thyroid-related biomarkers, were assessed, while the associations of biomarkers and clinical symptoms were also analyzed. The clinical variables and biomarkers were entered into the Cox regression model to identify the independent risks associated with time to achieve euthyroidism. Results The correlation matrix showed that free T4 was positively correlated either with T3 ( r = 0.755, P < 0.001) or renin ( r = 0.341, P = 0.002) but not with aldosterone ( r = 0.055, P = 0.631). In ROC analysis for biomarkers and clinical symptoms, either free T4 (AUC = 0.754, P < 0.001) or thyroid-stimulating hormone receptor antibody (TSHRAb) (AUC = 0.645, P = 0.026) demonstrated effective prediction of tachycardia; however, renin was slightly positive for tachycardia without significance (AUC = 0.580, P = 0.233). Regarding thyrotoxic periodic paralysis, the renin showed significant prediction power (AUC = 0.727. P = 0.021) rather than free T4 (AUC = 0.543, P = 0.748) or TSHRAb (AUC = 0.688, P = 0.063). The median time to achieve euthyroidism was 166 days for newly onset patients and 216 days for recurrence, but the time-to-event curves showed no difference (log rank P = 0.728). Under Cox regression modeling, TSHRAb was found to independently predict late euthyroidism (Hazard ratio 0.946, 95% confidence interval 0.901–0.993, P = 0.026), and the renin had no impact (HR 0.995, 95% CI 0.987–1.003, P = 0.215). Conclusions Renin but not aldosterone was positively correlated with free T4. Certain biomarkers measured at diagnosis were associated with hyperthyroid symptoms. Free T4 and TSHRAb might predict tachycardia, while renin might predict thyrotoxic periodic paralysis; nevertheless, only higher TSHRAb was associated with delayed euthyroid state achievement.