Aldosterone/renin ratio (ARR) is currently regarded as the most reliable and available screening test for primary aldosteronism (PA), however, the falling accuracy of ARR with increasing age has posed crucial challenge for PA screening among older-aged population. To clarify potential effects of age on screening for PA, 216 subjects with PA and 657 subjects with non-PA were recruited and subdivided into four age groups (⩽39, 40-49, 50-59 and ⩾60 years) and their biochemical parameters were compared. As expected, plasma renin activity (PRA) lowered more than plasma aldosterone concentration (PAC) and led to gradually elevated ARR with increasing age in the non-PA group (P<0.001), whereas this phenomenon was unconspicuous in the PA group. The best cut-off values of ARR for PA screening were elevated in subjects ⩾50 years, whereas the area under the receiver operating characteristic curves (AUCs), sensitivity, specificity and Youden's index (YI) of ARR were declined with increasing age, especially in patients ⩾60 years (AUC=0.863, sensitivity=95.2%, specificity=69.0%, YI=0.643). The AUCs of PAC increased with increasing age and even slightly surpassed that of ARR in patients ⩾60 years (AUCPAC=0.884). Our data suggest that the criteria of ARR for PA screening in patients ⩾50 years may need setting higher; the falling accuracy of ARR with increasing age, especially in patients ⩾60 years, could be improved by taking into account the absolute value of the PAC when applicable by the center.

Few attention has been directed to the potential effects of intermittent hypoxia experienced in obstructive sleep apnea on the integrity and permeability of intestinal barrier, particularly in adults. Therefore, we evaluated alteration in serum d-lactate concentration in middle-aged males with obstructive sleep apnea to value permeability of intestinal barrier. In this current cross-sectional study, consecutive 159 males were studied. Obstructive sleep apnea was determined by polysomnography and apnea hypopnea index ≥15 event/h was defined as obstructive sleep apnea. D-lactate, lipopolysaccharide binding protein, interleukin-1β, interleukin-6 and tumor necrosis factor-α by ELISA method. Nonobese obstructive sleep apnea (OSA) males showed significantly higher serum d-LA than did nonobese [1374.35 (816-1735) μg/L vs 1166.43 (730–1815) μg/L, P = .018], and obese non-OSA ones [1374.35 (816-1735) μg/L vs 1188.75 (736–1557) μg/L, P = .045], whereas serum LBP levels showed no differences within groups. Serum IL-1β was also slightly higher in nonobese OSA males, but with statistical significance, than in nonobese (19.39 ± 4.67 ng/L vs 17.25 ± 3.66 ng/L, P = .041), and obese non-OSA ones (19.39 ± 4.67 ng/L vs 17.42 ± 3.79 ng/L, P = .047), whereas other biomarkers, IL-6 and TNF-a did not show significant differences among groups. In stepwise multiple linear regression analysis, serum d-LA was independently positively associated with AHI (B = 5.577, P = .022), and ODI3 (B = 4.550, P = .024) and negatively with LSaO2 (B = −12.234, P = .019). Finally, we arrived at a conclusion that serum d-lactate was increased in nonobese middle-aged males with obstrutive sleep apnea, possibly suggesting existence of subclinical disruption of intestinal barrier, and showed significant associations with inflammatory mediators, possibly being involved in systemic inflammation of obstructive sleep apnea.