Urinary excretions of lipocalin-type prostaglandin D synthase predict renal injury in type-2 diabetes: a cross-sectional and prospective multicentre study

Backgrounds. Urinary excretions of lipocalin-type prostaglandin D synthase/beta-trace (L-PGDS) probably reflect the increased permeability of injured glomerular capillary walls of the kidney. We tested the hypothesis in cross-sectional and prospective studies that urinary L-PGDS excretions predict renal injury in type-2 diabetes. Methods. (1) In the cross-sectional studies, we evaluated whether urinary L-PGDS excretions were able to predict renal diseases in a pooled population including 793 healthy subjects and 200 patients with various forms of renal diseases. (2) We determined the cut-off point of urinary L-PGDS excretions to predict >= 30 mg/gCr albuminuria in 666 patients with type-2 diabetes. (3) In the prospective study, 121 type-2 diabetic patients with < 30 mg/gCr albuminuria were followed for almost 2 years to examine whether urinary L-PGDS excretions predict the future status of renal injury in type-2 diabetes. Results. (1) In the cross-sectional studies, receiver operating characteristic analysis revealed that urinary L-PGDS excretions better predicted the patients with kidney diseases than the other markers of renal injury. (2) It was also demonstrated that >= 4.2 mg/gCr urinary L-PGDS excretions better predicted >= 30 mg/gCr albuminuria in type-2 diabetic patients than other markers. (3) The prospective study revealed that in type-2 diabetic patients with < 30 mg/ gCr albuminuria, the patients with >= 4.2 mg/gCr urinary L-PGDS excretions more likely exhibited the renal injury during the follow-up periods than those with < 4.2 mg/gCr urinary L-PGDS excretions. Conclusions. Urinary L-PGDS excretions reflect the current increased permeability of injured glomerular capillary walls and better predict the future status of renal injury in type-2 diabetes with < 30 mg/gCr albuminuria.