It is not uncommon to dump certain amounts of protein in your urine, perhaps up to 150 mg/day. Of that less than 30 mg of albumin is basically considered in the normal range. If you do have kidney damage the protein levels will rise and when albumin reaches 30-300 mg/L you are said to have albuminuria and your doctor will start to check and treat you for kidney disease. I believe most doctors will wait to see if you have two back to back tests with high microalbumin or albumin before further evaluation and consideration of treatment of kidney disease. There is a good description of what it all means and a standard protocol in this paper.
ps. I had a microalbumin greater than 30 mg/L and my next test was normal. I found that exercise caused me to dump a little protein.
pps. Low carb or high protein with normal kidney function is not known to cause microalbuminuria or albuminuria.