GI assessment is foundational to functional medicine-because the gut is connected to every health and disease metric. Autoimmune disease, hormonal imbalances, neurological conditions, metabolic dysfunction-all roads lead back to the gut. But with multiple stool testing options available, knowing which test to order and when is critical. Ordering the wrong test wastes time and money. Worse, unreliable results lead to chasing ghosts-treating findings that aren't clinically relevant while missing what actually matters.