Gender‐ and disease‐specific urinary thioredoxin in chronic kidney disease patients with or without type 2 diabetic nephropathy

Aim The role of urinary ( U ‐) thioredoxin ( T rx), a class of small redox proteins, in physiological and pathological conditions, in addition to its gender specificity, has been insufficiently determined in chronic kidney disease ( CKD ) patients, especially in diabetes mellitus ( DM ) nephropathy. Methods U ‐ T rx was measured cross‐sectionally in 110 CKD outpatients with estimated glomerular filtration rate ( eGFR ) of >15 mL/min per 1.73 m 2 , namely, in 57 type 2 DM patients (male: n  = 41, female: n  = 16) and 53 non‐ DM patients (M: n  = 33, F : n  = 20), as well as 30 healthy controls (M: n  = 11, F : n  = 19). Comparisons were made among controls, DM and non‐ DM , and between M and F , with clinical parameters compared in each group. In addition, a comparison between average U ‐ T rx level and the changes of renal function during a one‐year period was performed. Results U ‐ T rx was significantly higher in females than in males in controls ( P  < 0.05) and in non‐ DM patients ( P  < 0.05). Multiple regression analysis revealed that urinary protein ( UP )/creatinine ( C r) ratio, female sex and HbA1c were independent factors affecting U ‐ T rx among all subjects (adjusted R 2  = 0.468). In DM patients, U ‐ T rx was negatively correlated with eGFR , especially in males, and positively correlated with UP / C r and NAG in both sexes (all P  < 0.01), as well as with systolic blood pressure in all ( P  < 0.05). Average U ‐ T rx was positively correlated with the rate of annual eGFR decline of male ( P  < 0.01) but not female DM patients. Conclusion U ‐ T rx might have a gender‐specific physiological and pathological role and be a potent marker of renal damage in DM nephropathy.