Appendix: Integration Tables — USMLE Step 1

📊 High‑Yield Disease‑Mechanism Correlations

Each row links a classic disease to its underlying biochemistry, key pathology, and primary pharmacological management. Use this table to anchor cross‑disciplinary knowledge.

Disease	Biochemistry	Pathology	Pharmacology
Diabetes mellitus	Glucose metabolism, ketogenesis, insulin signaling defects	Microvascular/macrovascular complications (retinopathy, nephropathy, atherosclerosis)	Insulin, oral hypoglycemics (metformin, sulfonylureas, GLP‑1 agonists, SGLT2 inhibitors)
Myocardial infarction	Troponin release, anaerobic metabolism, ATP depletion	Coagulative necrosis, neutrophil infiltration, scar formation	Antiplatelets (aspirin, clopidogrel), anticoagulants (heparin), β‑blockers, ACE inhibitors
Sickle cell disease	HbS polymerization (glutamic acid → valine), sickling under hypoxia	Vaso‑occlusion, hemolysis, autosplenectomy, acute chest syndrome	Hydroxyurea (↑HbF), transfusion, pain management, antibiotics
Cystic fibrosis	CFTR dysfunction (defective chloride channel)	Bronchiectasis, pancreatic insufficiency, meconium ileus, cirrhosis	CFTR modulators (ivacaftor, lumacaftor), pancreatic enzymes, mucolytics
Phenylketonuria (PKU)	Phenylalanine hydroxylase deficiency → accumulation of phenylalanine	Intellectual disability, microcephaly, hypopigmentation, musty odour	Dietary phenylalanine restriction, sapropterin (tetrahydrobiopterin)
Alzheimer disease	Amyloid‑β accumulation, tau hyperphosphorylation	Amyloid plaques, neurofibrillary tangles, neuronal loss	Cholinesterase inhibitors (donepezil), NMDA antagonist (memantine)
Osteoporosis	Calcium/phosphate metabolism, vitamin D deficiency	Trabecular bone loss, increased fracture risk	Bisphosphonates (alendronate), denosumab, teriparatide, calcium/vitamin D
Gout	Purine metabolism, uric acid overproduction/underexcretion	Monosodium urate crystal deposition, tophi, nephrolithiasis	NSAIDs, colchicine, allopurinol, febuxostat, probenecid
Peptic ulcer disease (H. pylori)	Urease production, acid secretion (gastrin, histamine)	Chronic gastritis, mucosal erosion, perforation	PPIs, H₂ blockers, triple/quadruple therapy (amoxicillin, clarithromycin, metronidazole)
Asthma	Leukotriene synthesis, IgE‑mediated mast cell activation	Airway inflammation, goblet cell hyperplasia, smooth muscle hypertrophy	β₂‑agonists (albuterol), inhaled corticosteroids, leukotriene modifiers (montelukast)

🧩 Organ System Integration Summary

Vertical integration across biochemistry, physiology, pathology, and pharmacology for each major organ system — the core of Step 1 and clinical reasoning.

System	Key Biochemistry	Key Physiology	Key Pathology	Key Pharmacology
Cardiovascular	Lipid metabolism, troponins, ATP production, nitric oxide	Cardiac cycle, hemodynamics, baroreflex, Frank‑Starling	Atherosclerosis, myocardial infarction, heart failure, hypertension	Antihypertensives, antiarrhythmics, anticoagulants, statins
Respiratory	Surfactant composition, hemoglobin, carbonic anhydrase	V/Q matching, gas exchange, ventilation control, oxygen‑hemoglobin dissociation	COPD, asthma, pneumonia, interstitial lung disease, lung cancer	Bronchodilators, corticosteroids, mucolytics, antibiotics
Renal	Acid‑base balance, electrolyte transport, ammonia metabolism	GFR, tubular reabsorption/secretion, urine concentration, RAAS	Glomerulonephritis, acute tubular necrosis, chronic kidney disease, renal cell carcinoma	Diuretics, ACE inhibitors, ARBs, phosphate binders, erythropoiesis‑stimulating agents
GI / Hepatic	Bilirubin metabolism, ammonia detoxification, bile acid synthesis	Digestion, absorption, motility, enterohepatic circulation	Cirrhosis, hepatitis, inflammatory bowel disease, pancreatitis	PPIs, H₂ blockers, antiemetics, ursodeoxycholic acid, lactulose
Endocrine	Hormone synthesis (steroids, thyroid), receptor signaling	Feedback loops (hypothalamic‑pituitary axes), glucose homeostasis, calcium balance	Diabetes mellitus, thyroid disorders, adrenal insufficiency, MEN syndromes	Insulin, oral hypoglycemics, levothyroxine, methimazole, glucocorticoids
Hematologic	Heme synthesis, coagulation cascade, globin structure	Hemostasis, erythropoiesis, leukocyte function	Anemias, leukemias, lymphomas, thrombophilia, bleeding disorders	Anticoagulants (warfarin, DOACs), antiplatelets, growth factors (EPO, G‑CSF)
Neurologic	Neurotransmitter synthesis (ACh, dopamine, GABA), ion channels	Action potentials, synaptic transmission, reflexes, autonomic function	Stroke, dementia, epilepsy, multiple sclerosis, Parkinson disease	Antiepileptics, antidepressants, antipsychotics, levodopa, cholinesterase inhibitors
Musculoskeletal	Collagen synthesis, calcium/phosphate metabolism, creatine kinase	Muscle contraction, length‑tension relationship, bone remodeling	Osteoporosis, osteoarthritis, rheumatoid arthritis, muscular dystrophies	NSAIDs, DMARDs (methotrexate, biologics), bisphosphonates, muscle relaxants
Reproductive	Steroid hormone synthesis, gonadotropin regulation	Menstrual cycle, spermatogenesis, pregnancy physiology	Endometriosis, PCOS, testicular tumors, breast cancer, gestational trophoblastic disease	Oral contraceptives, SERMs, aromatase inhibitors, GnRH agonists

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Integration Tables: Disease‑Mechanism Correlations & Organ System Summary