The Potential Clinical Application of a Lower Bilateral Adrenal LIMB Width Ratio (L/RW) in Patients with Bilateral Primary Hyperaldosteronism

Abstract

Objective: This study investigated the characteristics of the adrenal limbs of primary aldosteronism (PA) patients and evaluated the value of the adrenal limb width measurement for the differentiation of unilateral PA from bilateral PA. Methods: A total of 122 PA patients (93 unilateral PA, ages ranged from 23 to 72 years; 29 bilateral PA, ages ranged from 30 to 68 years) who had undergone successful adrenal venous sampling (AVS) and adrenal gland computed tomography (CT) scan were retrospectively included. The maximum width of each adrenal gland limb (normal area on CT images) was measured, the left adrenal limb width to right adrenal limb width ratio (L/Rw) was calculated, and its potential value in the differentiation of unilateral PA and bilateral PA was analyzed. Results: The mean widths of the left adrenal limbs and the right adrenal limbs were 0.52 ± 0.10 cm and 0.43 ± 0.09 cm in unilateral PA patients, versus 0.52 ± 0.10 cm and 0.49 ± 0.12 cm in bilateral PA patients. The L/Rw ratio was 1.22 ± 0.24 in unilateral PA patients and 1.11 ± 0.23 in bilateral PA patients (P<.05). In the subgroup of PA patients over 55 years of age, compared with AVS, the sensitivity and specificity of the L/Rw ratio at 1.06 for subtype classification were 75% and 82%, respectively. Conclusion: A lower L/Rw ratio, referring to the ratio of the left adrenal limb width to the right adrenal limb width, may be a predictor of bilateral PA, especially in PA patients over 55 years of age. Abbreviations: APA = aldosterone-producing adenoma; AVS = adrenal venous sampling; BAH = bilateral adrenal hyperplasia; BMI = body mass index; CT = computed tomography; L/Rw = ratio of left adrenal limb width to right adrenal limb width; PA = primary aldosteronism.