Decreased fractional excreion of sodium is caused by -

FeNa(fractional excretion of sodium) is - <1% in prenal azotemia Early in the course of sepsis associated AKI. Rhabdomyolysis ,hemolysis associated AKI Contrast nephropathy >1% in Ischemia associated AKI in the late course of sepsis associated AKI Tubular injury or ATN. Ref:Harrison 20 th edition pg no 2105 tab -304.1