Correlation Between Thyroid Function Parameters and Aldosterone–Renin Ratio in Patients With Primary Aldosteronism and Their Association With Target Organ Damage

Background Primary aldosteronism (PA) is one of the most common causes of secondary hypertension. The relationship between thyroid function parameters and the aldosterone–renin ratio (ARR) in PA patients, as well as their combined impact on target organ damage, remains incompletely understood. Methods We conducted a retrospective analysis of 317 patients with suspected or confirmed PA who underwent comprehensive endocrine evaluation, including thyroid function testing, plasma aldosterone concentration, plasma renin activity (PRA), ARR, and assessment of target organ damage. Biomarker correlation and regression analyses were performed in the whole cohort, while thyroid function subgroup comparisons were restricted to patients with confirmed PA. Suppressed renin activity was predefined as PRA < 1.0 ng/mL/h, with profound suppression defined as PRA < 0.5 ng/mL/h. Results Among 317 patients (54.9% male, 45.1% female), 229 (72.24%) were diagnosed with PA. Hypertension was present in 248 patients (78.23%), of whom 239 (75.39%) were classified as Grade 3 hypertension with very high cardiovascular risk. Thyroid dysfunction was observed in a subset of patients, with elevated TSH levels present among individuals with hypothyroid status. The mean TSH was 3.86 ± 2.41 μIU/mL, and the mean ARR was 48.058 ± 3.161. Significant correlations were found between TSH and ARR ( r = 0.35, p < 0.01). Patients with higher ARR values showed a higher prevalence of target organ damage, including coronary artery atherosclerosis (24.92%), carotid artery atherosclerosis (21.45%), and lacunar cerebral infarction (31.86%). Multiple regression analysis revealed that thyroid function abnormalities and elevated ARR were associated with an increased risk of target organ damage after adjustment for conventional risk factors. Conclusion Thyroid function parameters, particularly TSH and FT4, are significantly associated with ARR in patients with suspected or confirmed PA. Thyroid dysfunction and elevated ARR are associated with target organ damage, and their combined assessment may improve endocrine and cardiovascular risk stratification in PA‐related hypertension.