How is pathophysiology of pyruvate kinase deficiency?

RBC only glycolysis (no mitochondria), PK deficiency little or no ATP/NADH production, ATP deficiency affects Na+/K+ ATPase leading to osmotic instability and misshapes RBCs clear them in spleen (extravascular hemolysis). NADH deficiency decrease reducing power required to convert methemoglobin (Hb-Fe3+ to Fe2+) because of distal block, 2,3-DPG is increased, binds to Hb and alters its conformation (shifts OSC to right)