Podocyturia as an early marker of diabetic nephropathy

Eirini Lioudaki, Kostas Stylianou, Maria Panteri, Christianna Choulaki, Eugene Daphnis, Emmanuel Ganotakis



AIM: Podocyte injury plays a pivotal role in the pathogenesis and progression of diabetic nephropathy.. The aim of the present study was to examine whether patients with diabetes mellitus (DM) but without overt diabetic nephropathy may present podocyte markers in urine suggestive of early podocyte injury. PATIENTS AND METHODS: Seventy-nine patients with DM and 20 healthy controls were studied. The mRNA abundance of 3 podocyte-specific markers in urinary sediment was measured with real-time quantitative PCR. Clinical and laboratory parameters of both groups were recorded. RESULTS: Synaptopodin mRNA was detected in urinary sediment of all diabetics and healthy controls. Urinary expression of nephrin and/or podocin was reported in half of the diabetic patients, most of whom were normoalbuminuric. Among healthy controls, 5 had detectable levels of nephrin and/or podocin mRNA in urine. Diabetic patients with urinary expression of 2 or 3 podocyte markers did not differ significantly with regard to clinical and demographic characteristics from those with sole synaptopodin urinary expression. Urinary synaptopodin mRNA levels were weakly but significantly correlated with DM duration in diabetics (p<0.05). There was also a positive correlation between nephrin and podocin mRNA levels both in patients with DM and healthy controls (p<0.001). CONCLUSIONS: The presence of podocyte-associated molecules in the urine of diabetic patients with normoalbuminuria and presumably normal renal function may indicate increased urinary podocyte exretion. The utility of such measurements in the prediction and staging of diabetic nephropathy warrants further investigation. Prospective studies will also show whether prompt initiation of medical treatment as soon as podocyturia is discovered may withhold the progression of the disease.