High protein in urine most likely indicates damage to the:

1. The filter normally retains protein. 2. Leakage points at the filter itself. 3. When higher amounts of protein are found, damage to the glomeruli is the likely basis. 4. So the answer is the glomeruli. _Source: OpenStax 'Anatomy and Physiology 2e', Ch 25 'The Urinary System'_