Solving a myth: Does boric acid stabilize aldosterone in urine at typical clinical laboratory storage conditions?

Aldosterone is produced by the adrenal gland and plays an important role in blood pressure regulation and electrolyte hemostasis. Clinically, measurement of urine aldosterone provides evidence for the diagnosis of hyper- and hypo-aldosteronism. Urine specimen that is collected in consecutive 24 h is preferred, which mitigates the risk of misdiagnosis due to large diurnal variation in aldosterone secretion. Preservatives such as boric acid are routinely added to the collection containers prior to urine collection. However, little is known of the effectiveness of these preservatives on stabilizing aldosterone in urine. In the current study, we examined the stability of urine aldosterone under typical clinical laboratory storage conditions with and without the supplementation of boric acid. Our result demonstrated that the addition of boric acid is unnecessary.