Background: Microalbuminuria is the earliest clinical sign of diabetic nephropathy (DN). However, earlier markers as a diagnostic tool for DN was required for the invalid of microalbuminuria in some cases. Osteoinductive factor (OIF) was known to be an essential component of the normal vascular matrix. We aimed to research the relationship between DN and OIF, and discussed the availability of the serological markers for earlier stage of DN.
Method: One hundred twenty Chinese subjects, who included patients with type 2 diabetes mellitus (T2DM), DN with microalbuminuria, and DN with macroalbuminuria, as well as healthy controls, were enrolled in this study. Serum OIF levels were examined by ELISA and other clinical biochemical parameters were tested based on standard methods.
Results: Our results indicated that, serum OIF levels were significantly increased in DN subjects compared with healthy and T2DM subjects (P<0.05 respectively). However, no significant changes in serum OIF levels were found between T2DM and healthy subjects. Furthermore, serum OIF had negative correlation with estimated glomerular filtration rate (eGFR) and positive correlation with blood urea nitrogen(BUN) and creatinine. ROC curve analysis showed that serum OIF level was a good sensitive and specificity marker for microalbuminuria and early renal damage with sensitivity of 86.7% and specificity of 95%, as well as for macroalbuminuria and damage progress with sensitivity of 90% and specificity of 95%.
Conclusion: OIF may be an indicator of the earlier-stage DN in subjects with T2DM. Understanding the exact mechanism of up-regulated OIF in subjects with DN requires further study.
Keywords: Diabetic nephropathy; biomarker; early diagnosis; osteoinductive factor.