is microalbuminuria an indication of renal biopsy?

Answer 1

No, it can indicate renal failure, though. Albumin is one of the smallest proteins, and will be the first lost if there is kidney hypertension, or nephritis.
A biopsy is where they stick a needle in your kidney to get a sample of it to look at it under a microscope. There are other kidney function tests they would do before a biopsy, including other biochemical tests, ultrasound, etc.