Q: Which one other test beside Glomerular Filtration Rate (GFR) and Serum Creatinine (SCr) , can be used in early stage to detect 'Contrast Induced Nephropathy'?

Answer:  Serum cystatin C 

Cystatin C is a protein that is produced throughout in the body by all cells. It contains a nucleus. It is filtered from the blood by the kidneys, and broken down at a constant rate. It is has been found to be an accurate marker of GFR.

Compared with SCr, cystatin C changes much earlier after contrast administration and is not subject to confounding factors, such age, sex, and muscle mass, that influence SCr values independent of the underlying GFR.

Cystatin C is increasingly being used as a marker of renal function in cardiac surgical patients.

Reference:

Droppa M, Desch S, Blase P, et al. Impact of N-acetylcysteine on contrast-induced nephropathy defined by cystatin C in patients with ST-elevation myocardial infarction undergoing primary angioplasty. Clin Res Cardiol. Jun 28 2011