That looks like it was measured with a urinary dipstick. This method of measuring urinary protein is a bit crude. It also depends what units are used to measure on that particular urinalysis strip. If it is in mg/dl, then 15 would just be above the limit of detection - so it is only mildly elevated. A urinary protein (or albumin) to creatinine ratio could be done to provide a better estimate but the levels are likely low.