Evaluation of bladder function in newly diagnosed thyrotoxicosis patients: a prospective controlled study

Background Thyroid hormone excess increases β-adrenergic activity and causes autonomic imbalance, particularly in the cardiovascular system. Because bladder storage and voiding depend on a balance between sympathetic and parasympathetic activity, thyrotoxicosis may also affect lower urinary tract function. However, evidence is limited to a few small studies with inconsistent findings, and it remains unclear whether lower urinary tract symptoms and objective bladder function change after the restoration of euthyroidism. This is clinically relevant, as urinary symptoms in thyrotoxicosis may be overlooked. This study aimed to evaluate lower urinary tract symptoms and bladder function in newly diagnosed thyrotoxicosis before and after treatment, compared with healthy controls. Methods In this prospective controlled cohort study, 40 patients aged 18–50 years with newly diagnosed thyrotoxicosis were evaluated at baseline and after achieving euthyroidism, and compared with 37 healthy controls matched for age, sex and body mass index. Lower urinary tract symptoms were assessed with the International Prostate Symptom Score (IPSS), and bladder function with uroflowmetry and ultrasonographic post-void residual (PVR) volume. Parametric and non-parametric tests, Spearman correlation and multivariable linear regression were used. Results At baseline, 28 patients (70%) had moderate symptoms; after treatment, 38 (95%) had mild symptoms. Mean IPSS decreased from 7.03 ± 3.32 to 1.95 ± 1.71 (mean change − 5.08, 95% CI − 6.10 to − 4.05; p < 0.001) and was higher than in controls both before and after treatment ( p < 0.001). The improvement remained significant after multivariable adjustment ( p < 0.001) and was similar in patients not receiving antithyroid drugs. Symptoms were almost exclusively storage symptoms, mainly frequency and nocturia. Uroflowmetric parameters and PVR did not change after treatment or differ from controls. A borderline inverse correlation was found between pre-treatment free thyroxine and maximum flow rate ( ρ = − 0.31, 95% CI − 0.57 to − 0.00; p = 0.050). Conclusions Lower urinary tract symptoms are common in thyrotoxicosis and improve significantly after treatment, independently of measured confounders, whereas uroflowmetric parameters and PVR do not change within a short follow-up. IPSS may be useful for symptom assessment in thyrotoxicosis. Larger studies with longer follow-up and urodynamic assessment are needed. Trial registration Not applicable.