What causes metabolic acidosis and how does the body compensate?

Metabolic acidosis occurs when bicarbonate is low, either from excessive acid production or bicarbonate loss. Common causes include diabetic ketoacidosis, lactic acidosis from tissue hypoxia, renal failure, severe diarrhea which loses bicarbonate, and salicylate overdose. The body compensates through respiratory mechanisms: the lungs increase rate and depth of breathing, called Kussmaul respirations, to blow off carbon dioxide and raise the pH. Lab findings show pH below 7.35, bicarbonate below 22, and compensatory PaCO2 below 35 as the lungs work to correct the imbalance.