Otozomal dominant polikistik böbrek hastalarinda podosit hasar belirteçlerinin proteinüri ile ilişkisi

Introduction-Objective: Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disease that is characterized by the abnormal proliferation of the tubular cells, abnormal fluid secretion in tubular cells, and abnormal extracellular matrix synthesis leading to the development of multiple renal cysts. In tubulo-interstitial diseases, the kidney injury may also involve the glomeruli with progression of the condition, causing injury to the podocytes in the glomeruli. In this controlled study, our aim was to assess and compare the urinary excretion of podocin (a protein found in the slit diaphragm of the podocyte), and podocalyxin (a molecule found in the apical membrane of the podocyte) as well as their association with the level of proteinuria. Materials and Methods: A total of 56 ADPKD patients and 28 age, gender, and BMI matched healthy controls were involved in this study. Demographic data, comorbid conditions, medical family history, use of medications, clinical signs of ADPKD, and blood pressure values were recorded for all patients. Also complete blood count and routine biochemistry tests were done. Glomerular filtration rate (GFR) was calculated using MDRD formula. Podocin, podocalyxin and proteinuria determinations were performed on spot urinary samples. ADPKD patients were assessed with regard to both their GFR levels (< 60 ml/min/1.73 m2 vs. > 60 ml/min/1.73 m2) and presence/absence of hypertension (HT). Results: As compared to controls ADPKD patients had lower GFR, and higher blood pressure as well as urinary protein, podocin and podocalyxin. When two subgroups of ADPKD patients defined on the basis of GFR were compared, those with a GFR < 60 ml/min/1.73 m2 had higher blood pressure, incidence of HT and proteinuria. In those with a GFR < 60 ml/min/1.73 m2 podocin was higher as compared to those with a GFR > 60 ml/min/1.73 m2 and controls, while in those with a GFR > 60 ml/min/1.73 m2 podocin was significantly higher than in controls. On the other hand, podocalyxin was only significantly higher in the group with a GFR < 60 ml/min/1.73 m2 than in controls. Comparison ADPKD patients with or without the presence of HT showed no significant differences in proteinuria, podocin, and podocalyxin. While there was a positive correlation between podocin and podocalyxin and a negative correlation between podocin and GFR, podolcalyxin had no significant correlation with GFR. Podocin levels in ADPKD patients were negatively correlated with the age in both GFR groups (i.e. > 60 ml/min/1.73 m2 and < 60 ml/min/1.73 m2). However, no significant correlation was established between proteinuria and podocin or podocalyxin in either group. Conclusion: Proteinuria and podocyte injury are more common in ADPKD patients as compared to the general patient. Absence of a significant association between podocyte injury and proteinuria suggests that the development and level of proteinuria in this patient group may not be explained on the basis of glomerular injury or HT alone, and that other pathological processes may also play a role in the occurrence of cysts.