Learn / FMK
Every FMK condition
299 diseases, deficiencies, toxicities and drug mechanisms harvested from every FMK deck — the ones sprinkled through a single bullet as much as the ones with their own slide. Pick what you're given and what you have to name, or let it cycle; distractors come from the same category so you have to discriminate (hypoketotic vs. ketotic hypoglycemia, which GSD, which urea-cycle enzyme…). Every answer shows the whole card with the lecture and slide.
Toxin/Drug · FMK 08.4
Isoniazid-induced vitamin B6 (pyridoxine) deficiency Acquired / not inherited
Defect / target: Isoniazid antagonizes/depletes pyridoxal phosphate, the cofactor of ALA synthase
Mechanism: Isoniazid binds and inactivates pyridoxal phosphate, impairing PLP-dependent ALA synthase (and other PLP enzymes), which can unmask sideroblastic changes or worsen porphyria-like presentations.
↑ Accumulates: Iron in erythroid mitochondria (sideroblastic changes)· ↓ Deficient: Pyridoxal phosphate (vitamin B6); ALA / heme synthesis
Presentation: Sideroblastic anemia, peripheral neuropathy on isoniazid therapy
Labs: Ring sideroblasts, microcytic anemia
Treatment: Co-administer pyridoxine (vitamin B6) with isoniazid
ALA synthase needs PLP, like transaminases and decarboxylases
Learn the mechanism: Heme synthesis (porphyrias) →
FMK 08.4 Heme Metabolism · slide 9