HMP Shunt (Pentose Phosphate Pathway)
| Rate-Limiting Enzyme: | Glucose-6-Phosphate Dehydrogenase (G6PD) |
| Primary Yield: | NADPH (Oxidative phase) & Ribose-5-Phosphate |
| Thiamine-Dependent: | Transketolase (Non-oxidative phase, requires Vitamin B1) |
| Net ATP Generation: | 0 ATP |
High-Yield Core Realities:
- NADPH Purpose: Drives anabolic reduction (fatty acid/steroid synthesis) and keeps **glutathione reduced** to neutralize peroxides in RBCs.
- G6PD Deficiency: X-linked recessive. Oxidative stress (Infections, Fava beans, Primaquine, Dapsone) causes hemoglobin denaturation → **Heinz bodies** and **Bite cells**.
- Diagnostic Trap: G6PD enzyme levels can test *falsely normal* during acute hemolysis because older deficient cells have already died, leaving younger reticulocytes.
- CGD Connection: NADPH fuels NADPH Oxidase for phagocytic respiratory burst. Deficiency leads to Chronic Granulomatous Disease (**catalase-positive infection risk**).