Urinary sodium/potassium ratio as a screening tool for hyperaldosteronism in men with hypertension

Area of Science:

• Endocrinology
• Nephrology
• Primary Care Medicine

Background:

• Secondary hypertension affects approximately 10% of hypertensive individuals.
• Hyperaldosteronism is a common cause of secondary hypertension, yet often remains undiagnosed.
• Current diagnostic methods can be complex and costly, limiting widespread screening.

Purpose of the Study:

• To investigate the utility of the urinary sodium/potassium ratio (Na/K) as a simple screening tool for hyperaldosteronism.
• To assess the association between the second morning urine Na/K ratio (SMU Na/K) and high plasma aldosterone concentration (PAC) in hypertensive patients.
• To evaluate the diagnostic performance of SMU Na/K for detecting hyperaldosteronism in primary care and health examination settings.

Main Methods:

• Recruited 160 hypertensive individuals (age 30-69) not on antihypertensive medication.
• Measured urinary sodium (Na) and potassium (K) from second morning urine samples.
• Measured plasma aldosterone concentration (PAC) and analyzed the association with SMU Na/K using receiver operating characteristic (ROC) curves.

Main Results:

• The area under the ROC curve for SMU Na/K and high PAC was 0.77 in men and 0.64 in women.
• In men, an SMU Na/K <1.0 demonstrated a sensitivity of 45.5% and a specificity of 97.9% for detecting hyperaldosteronism.
• Positive and negative predictive values for men were 71.4% and 94.1%, respectively.

Conclusions:

• The urinary Na/K ratio shows potential as a cost-effective screening tool for hyperaldosteronism.
• SMU Na/K appears particularly useful for screening hypertensive men, offering high specificity.
• Further research may refine its application in diverse hypertensive populations.