Avrum Gillespie, MD, Professor of Medicine at the Lewis Katz School of Medicine at Temple University, offered insight to Everyday Health about focal segmental glomerulosclerosis (FSGS), a condition that damages the filters in the kidneys and limits their ability to filter waste from blood. That waste buildup can then cause someone to feel tired and weak. Dr. Gillespie offered some suggestions on strategies for coping with FSGS fatigue and for feeling more energized.