contrast nephropathy

Everyone who got cronic renal failure presented with unstable angina or severe chest pain and require angioplasty intervention are warned about possible contrast nephropathy .
What the hell is that?
I will give you some brief account about that.
Cotrast nephropathy is impairment of renal function occured within 3 days of IV contrast.
Recovers in few days,Rarely irreversible.
Contrast nephropathy is peaked at 4-5 days and returns to baseline within 7-10 days. Renal function can persists up to 3 weeks.

Patient with impaired renal funtion.Iodinated contrast is nephrotoxic causing renal vasoconstiction and direct toxic effects upon renal tubules.
Is anyone with normal renal function carries the risk.
Risk factor for contrast nephropathy are
A:renal insufficiency
60% of pt develop contrast nephropathy had preexisting renal insufficiency.
The greater the impairment the greater the risk.
B:Diabetis mellitus(DM)
Pt with DM and preexisting renal insufficiency carries higher risk compare to nondiabetis with renal insufficiency develop contrart nephropathy.
But DM with normal renal function carries same risk as non diabetic pt.
C:Volume of contrast
The higher the amount the higher the risk
D:multiple myeloma
McCarthy found that is no increase incidence for nephropathy but previously they say yes.
How to prevent it
The main stay is hydration
Hydration with normal saline.
How about N acetyl cysteine?
Some evidence said benefit some say not.