Which of the following tests is most sensitive for detecting early diabetic nephropathy

In the 40% of patients with diabetes who develop diabetic nephropathy ,the earliest manifestation is an increase in abluminuria detected by sensitive radioimmunoassay. Abluminuria in the range of 30-300 mg/24hr is called Microalbuminuria It is currently recommended to test for Microalbuminuria 5 years after diagnosis of type 1 and yearly thereafter At the time of diagnosis for type 2 and yearly thereafter. Ref:Harrison 20 th edition pg no 2145