The 20 must-knows, per system.

ACS pathway. STEMI = ST elevation in 2 contiguous leads → cath lab within 90 min (lytics within 30 if no PCI in 120). NSTEMI/UA = troponin ± ST depression → heparin, DAPT, early cath. Aspirin, nitrates, beta-blocker unless RV infarct/shock.

MI by lead. II, III, aVF = inferior (RCA; check right-sided V4R — no nitrates if RV). V1–V4 = anterior (LAD). I, aVL, V5–6 = lateral (circumflex). ST depression V1–V3 with tall R = posterior.

Post-MI complications. Days 1–3: arrhythmia, cardiogenic shock. Days 3–7: free-wall rupture (tamponade), papillary muscle rupture (new MR), VSD (new murmur + thrill). Weeks: Dressler, aneurysm.

Heart failure. HFrEF (EF ≤40%): ARNI/ACEi + beta-blocker + MRA + SGLT2i — all four, titrated. HFpEF: SGLT2i, diuretics, control BP/AF. Acute decompensation: IV loop diuretic, nitrates, BiPAP; no beta-blocker initiation while wet.

Atrial fibrillation. Rate control (beta-blocker/diltiazem) for most; rhythm control if symptomatic or new. Anticoagulate by CHA₂DS₂-VASc ≥2 (men) / ≥3 (women): DOAC > warfarin (warfarin for mechanical valve, mitral stenosis). Cardiovert unstable now; stable = 3 weeks anticoagulated or TEE first.

Tachycardia rules. Unstable = synchronized cardioversion. SVT: vagal → adenosine. WPW with AF: procainamide/ibutilide — never AV-nodal blockers. Monomorphic VT stable: amiodarone. Torsades: magnesium, stop QT drugs. VF/pulseless VT: defibrillate.

Bradycardia & blocks. Symptomatic: atropine → pacing → epi/dopamine. Mobitz I (Wenckebach) = observe. Mobitz II and 3rd-degree = pacemaker. Any new high-grade block after inferior MI: pace.

Murmurs — systolic. Aortic stenosis: crescendo-decrescendo, radiates to carotids, ↓ with Valsalva; syncope/angina/HF = replace. HOCM: ↑ with Valsalva/standing, ↓ with squatting. MR: holosystolic at apex → axilla. VSD: holosystolic LLSB with thrill.

Murmurs — diastolic. Aortic regurgitation: decrescendo at LSB, wide pulse pressure, water-hammer pulse. Mitral stenosis: opening snap + diastolic rumble at apex, AF, rheumatic history. Diastolic murmurs are always pathologic.

Endocarditis. Fever + new murmur + risk (IVDU → tricuspid, S. aureus; prosthetic valve; dental → viridans). Three blood cultures before antibiotics, then echo (TEE if TTE negative). Prophylaxis only for prosthetic valve, prior endocarditis, cyanotic CHD, transplant valvulopathy — amoxicillin 2 g before dental work.

Pericardial disease. Pericarditis: pleuritic pain better sitting forward, friction rub, diffuse ST elevation with PR depression → NSAID + colchicine. Tamponade: Beck triad, pulsus paradoxus >10, electrical alternans → pericardiocentesis. Constriction: Kussmaul sign, pericardial knock.

Cardiomyopathies. Dilated: systolic failure (alcohol, viral, doxorubicin, peripartum). Hypertrophic: young athlete syncope/sudden death, family history — beta-blocker, avoid dehydration/nitrates, ICD if high risk. Restrictive: amyloid, sarcoid, hemochromatosis. Takotsubo: stress, apical ballooning, clean coronaries.

Hypertension numbers. Normal <120/80; stage 1 130–139/80–89; stage 2 ≥140/90. Target <130/80 for nearly all. First-line: thiazide (chlorthalidone), ACEi/ARB, CCB. Two drugs at stage 2. Emergency = organ damage: MAP −20–25% in hour 1.

Aortic dissection. Tearing chest/back pain, pulse or BP differential, widened mediastinum; CTA (TEE if unstable). Type A (ascending) = surgery. Type B = medical. First drug is esmolol/labetalol to HR <60 and SBP <120 — beta-blocker before any vasodilator.

Shock by numbers. Hypovolemic: ↓CVP, ↓CO, ↑SVR — fluids/blood. Cardiogenic: ↑CVP, ↓CO, ↑SVR — inotropes, no fluids. Septic: ↓SVR, ↑CO early — 30 mL/kg crystalloid, norepinephrine. Obstructive: tamponade, tension pneumothorax, massive PE — relieve the obstruction.

Syncope. Cardiac syncope (exertional, no prodrome, structural disease, abnormal ECG) is admitted and worked up: echo, monitor. Vasovagal: prodrome, trigger, reassure. Orthostatic: drop ≥20/10 — volume, review meds. Every syncope gets an ECG.

Peripheral arterial disease. Claudication, ABI ≤0.9 (>1.4 = calcified, use toe-brachial). Supervised exercise, statin, antiplatelet, cilostazol (not in HF); revascularize for limb threat/rest pain. Acute limb ischemia (6 Ps) = heparin and vascular surgery now.

DVT / venous disease. Wells → D-dimer (low risk) or duplex. Anticoagulate 3 months provoked, indefinite unprovoked/recurrent; DOAC first-line. Superficial thrombophlebitis near the saphenofemoral junction gets anticoagulated. Chronic venous insufficiency: compression, elevation, ulcer over the medial malleolus.

Lipids. High-intensity statin for ASCVD, LDL ≥190, diabetes 40–75 with risk, or 10-year risk ≥20%; moderate for 7.5–20%. Add ezetimibe then PCSK9 inhibitor if LDL stays ≥70 in very high risk. Myalgia: check CK, try a different statin or alternate-day dosing.

Cardiac arrest. CPR 100–120/min, defibrillate shockable rhythms (epinephrine every 3–5 min, amiodarone after 3rd shock). PEA/asystole: epinephrine, find the Hs and Ts. Targeted temperature management for comatose survivors. Hypothermia: rewarm before calling it.

Asthma control. Step therapy: ICS-formoterol as reliever and maintenance (GINA), or SABA + daily ICS. Add LABA before raising ICS dose. Never LABA alone. Spirometry: obstructive with ≥12% and 200 mL bronchodilator reversibility.

Asthma exacerbation. Peak flow <50% or can't speak in sentences = severe. Nebulized albuterol + ipratropium, systemic steroids within the hour, magnesium if severe. Normal or rising PaCO₂ in a tiring asthmatic = impending failure — ICU, intubate.

COPD. FEV₁/FVC <0.70 post-bronchodilator. GOLD groups A/B/E: bronchodilator → LABA + LAMA → add ICS only with eosinophils ≥300 or frequent exacerbations. Only smoking cessation, oxygen (PaO₂ ≤55 or SpO₂ ≤88%), and lung reduction in selected patients change mortality.

COPD exacerbation. SABA/SAMA, prednisone 40 mg × 5 days, antibiotics if increased purulence or ventilated (azithromycin, doxycycline, amoxicillin-clavulanate). Target SpO₂ 88–92%. BiPAP for pH <7.35 with PaCO₂ >45 — it reduces intubation and mortality.

Pneumonia. CURB-65 / PSI decide admission. Outpatient healthy: amoxicillin or doxycycline (macrolide if resistance <25%). Comorbid: amoxicillin-clavulanate + macrolide, or respiratory FQ. Inpatient: beta-lactam + macrolide or FQ. Cover MRSA/Pseudomonas only with prior isolation or recent IV antibiotics + hospitalization.

Pneumonia clues. Atypical (Mycoplasma): young, dry cough, cold agglutinins. Legionella: hyponatremia, diarrhea, hot tubs — urine antigen, FQ/azithromycin. Aspiration: right lower lobe, alcohol/stroke. Klebsiella: currant-jelly sputum, alcoholic. PJP: HIV CD4 <200, ↑LDH, ground glass — TMP-SMX + steroids if PaO₂ <70.

Tuberculosis. Latent: IGRA/TST positive, normal CXR → rifampin 4 months or INH 9 months (INH + pyridoxine). Active: RIPE × 2 months then RI × 4; airborne isolation; sputum × 3. Rifampin turns fluids orange and induces CYP; ethambutol = optic neuritis; INH = hepatitis, neuropathy; PZA = hyperuricemia.

Pulmonary embolism. Wells: low → PERC/D-dimer; high → CTA (V/Q if contrast contraindicated; pregnancy → duplex then V/Q). Anticoagulate before imaging if high suspicion. Massive (hypotension) = thrombolysis or embolectomy. Sub-massive with RV strain: anticoagulate, monitor. Three months provoked; indefinite unprovoked.

Pneumothorax. Tension: hypotension, tracheal deviation, absent breath sounds → needle decompression then chest tube; never wait for X-ray. Primary spontaneous small (<2–3 cm, stable): oxygen and observe. Large or symptomatic: aspiration or chest tube. Recurrent: pleurodesis.

Pleural effusion. Light criteria for exudate (any one): fluid/serum protein >0.5, LDH >0.6, LDH >2/3 upper normal. Transudate = HF, cirrhosis, nephrotic. Exudate = infection, malignancy, PE. Complicated parapneumonic (pH <7.2, glucose <60, positive culture) or empyema = chest tube.

Lung nodule & cancer. Nodule >8 mm or growing = PET/biopsy; <6 mm in low risk = no follow-up. Screen annual low-dose CT: age 50–80, ≥20 pack-years, quit <15 years ago. Small cell: central, smoker, SIADH/Lambert-Eaton/Cushing — chemo, not surgery. Squamous: central, cavitary, PTHrP hypercalcemia. Adenocarcinoma: peripheral, non-smokers.

Lung cancer syndromes. Pancoast: shoulder pain, Horner syndrome, brachial plexus. SVC syndrome: facial plethora, arm swelling, dilated neck veins — small cell or lymphoma. Hoarseness = recurrent laryngeal nerve.

Interstitial lung disease. Progressive dyspnea, dry cough, bibasilar Velcro crackles, clubbing, restrictive PFTs with ↓DLCO. IPF: honeycombing, UIP pattern → nirtedanib/pirfenidone, transplant. Sarcoid: bilateral hilar adenopathy, non-caseating granulomas, ↑ACE, hypercalcemia, erythema nodosum — steroids if symptomatic. Hypersensitivity pneumonitis: remove the antigen.

Occupational lung. Asbestos: pleural plaques, lower lobes, mesothelioma; lung cancer risk multiplied by smoking. Silica: upper lobes, eggshell hilar calcification, TB risk. Coal: upper lobes. Berylliosis: mimics sarcoid. Byssinosis: Monday chest tightness.

Obstructive sleep apnea. Snoring, witnessed apneas, daytime sleepiness, BMI ↑, neck circumference. Polysomnography: AHI ≥5 with symptoms or ≥15. CPAP first-line; weight loss; treat because of hypertension, AF, and stroke risk. Obesity hypoventilation adds daytime PaCO₂ >45.

ARDS. Acute bilateral infiltrates, PaO₂/FiO₂ ≤300, not cardiogenic (normal wedge). Lung-protective ventilation: 6 mL/kg ideal body weight, plateau <30, permissive hypercapnia, PEEP; prone for P/F <150. Treat the cause (sepsis, aspiration, pancreatitis, transfusion).

Cystic fibrosis. Recurrent sinopulmonary infection, pancreatic insufficiency, meconium ileus, infertility. Sweat chloride ≥60 → CFTR genetics. Pseudomonas and Burkholderia colonization. Airway clearance, dornase alfa, hypertonic saline, CFTR modulators (elexacaftor/tezacaftor/ivacaftor), pancreatic enzymes, fat-soluble vitamins.

Hemoptysis. Massive (>100–600 mL/24 h): airway first, bleeding side down, bronchoscopy/bronchial artery embolization. Common causes: bronchitis, bronchiectasis, TB, cancer, PE. Everyone gets a CXR; CT if smoker >40 or persistent.

Oxygen & ventilation. Hypoxemia with normal A-a gradient = hypoventilation or high altitude. Widened gradient: V/Q mismatch (corrects with O₂) vs shunt (does not). Long-term O₂ criteria: PaO₂ ≤55 or SpO₂ ≤88%, or ≤59/89 with cor pulmonale/polycythemia. BiPAP for hypercapnic failure; CPAP for cardiogenic edema/OSA.

Pulmonary hypertension. Mean PA pressure >20 mmHg on right heart catheterization; echo screens. Group 1 (PAH): idiopathic, scleroderma, drugs → PDE5i, endothelin antagonists, prostacyclins. Group 2 (left heart) and 3 (lung disease/hypoxia) = treat the cause; group 4 (CTEPH) = anticoagulate, thromboendarterectomy. Loud P2, RV heave, right heart failure.

GERD & Barrett. Typical GERD: 8-week PPI trial; EGD for alarm features (dysphagia, weight loss, bleeding, age >60 new onset) or refractory symptoms. Barrett = intestinal metaplasia → surveillance EGD; dysplasia → ablation. PPI long-term: fracture, C. diff, B12, magnesium.

Peptic ulcer & H. pylori. Duodenal ulcer pain improves with food; gastric worsens. Test: stool antigen or urea breath test off PPI × 2 weeks; biopsy on EGD. Treat: bismuth quadruple (PPI + bismuth + tetracycline + metronidazole) 14 days; confirm eradication ≥4 weeks after. Gastric ulcers get repeat EGD to exclude cancer.

Upper GI bleed. Two large IVs, fluids, type and cross, PPI drip, EGD within 24 h (12 h if variceal). Variceal: octreotide, ceftriaxone, band ligation, TIPS if refractory; beta-blocker for secondary prevention. Transfuse at Hb <7 (8 with CAD). Glasgow-Blatchford 0–1 = outpatient.

Lower GI bleed. Diverticulosis = painless bright red bleeding, most common. Angiodysplasia = elderly, aortic stenosis. Ischemic colitis = elderly, pain then bloody diarrhea, watershed areas. Exclude an upper source (NG lavage/EGD) if hemodynamically significant; colonoscopy after prep; CTA if brisk.

Dysphagia. Solids only, progressive = mechanical (cancer, stricture, Schatzki ring) → EGD. Solids and liquids from the start = motility (achalasia: bird-beak esophagram, manometry; scleroderma). Oropharyngeal (coughing, nasal regurgitation) = neurologic → modified barium swallow.

Acute pancreatitis. Two of three: epigastric pain to the back, lipase >3× normal, imaging. Gallstones and alcohol lead. Aggressive lactated Ringer's, analgesia, early oral feeding; no routine antibiotics; ERCP only for cholangitis or persistent obstruction; cholecystectomy same admission for gallstone pancreatitis. Necrosis/organ failure = severe.

Gallbladder. Biliary colic: RUQ ultrasound, elective cholecystectomy. Cholecystitis: Murphy sign, wall thickening/pericholecystic fluid, HIDA if unclear → antibiotics + cholecystectomy within 72 h. Choledocholithiasis: dilated duct, ↑ALP/bilirubin → ERCP. Cholangitis (Charcot triad ± Reynolds pentad) = antibiotics + urgent ERCP.

Hepatitis serology. HBsAg+ = infected; anti-HBs alone = vaccinated; anti-HBs + anti-HBc IgG = recovered; IgM anti-HBc = acute (window period). HBeAg = high replication. Hepatitis C: antibody then RNA; treat everyone with DAAs 8–12 weeks. Hepatitis A/E: fecal-oral, self-limited (E is dangerous in pregnancy).

Cirrhosis complications. Ascites: diuretics (spironolactone:furosemide 100:40), salt restriction; SBP = PMN ≥250 → ceftriaxone + albumin, then prophylaxis. Varices: screen EGD, non-selective beta-blocker. Hepatic encephalopathy: lactulose ± rifaximin, find the trigger. HCC: ultrasound + AFP every 6 months.

Liver labs pattern. AST:ALT >2 = alcohol. ALT >>1,000 = viral, ischemic, acetaminophen. ↑ALP with ↑GGT = cholestatic → ultrasound; PBC (AMA, middle-aged woman, ursodiol), PSC (IBD, beading on MRCP). Hemochromatosis: ferritin/TSAT ↑, phlebotomy. Wilson: young, Kayser-Fleischer rings, low ceruloplasmin. Autoimmune: ANA/ASMA, steroids.

Acetaminophen. Rumack-Matthew nomogram from 4 h post-ingestion; N-acetylcysteine if above the line, unknown timing, or any hepatotoxicity — it works best within 8 hours. King's College criteria for transplant referral.

Inflammatory bowel disease. Crohn: skip lesions, transmural, mouth-to-anus, fistulas, cobblestoning, non-caseating granulomas, B12/bile-acid malabsorption. UC: continuous from rectum, mucosal, bloody diarrhea, toxic megacolon, colon cancer surveillance at 8 years, PSC. Induction: 5-ASA (UC), steroids; maintenance: thiopurines, anti-TNF. Colectomy cures UC.

Diarrhea by clue. Bloody + fever = invasive (Shigella, Campylobacter, EHEC — no antibiotics for O157:H7/HUS risk). Recent antibiotics = C. difficile → oral vancomycin or fidaxomicin; fulminant = vancomycin + IV metronidazole. Hikers/travelers = Giardia (metronidazole). Chronic + weight loss = celiac, IBD, malabsorption.

Celiac disease. Diarrhea, bloating, iron-deficiency anemia, dermatitis herpetiformis, osteoporosis. Tissue transglutaminase IgA (with total IgA) while eating gluten; duodenal biopsy villous atrophy confirms. Gluten-free diet; screen for deficiencies; lymphoma risk if untreated.

Colorectal screening. Average risk: start at 45 — colonoscopy every 10 years, FIT yearly, or stool DNA every 3 years. First-degree relative with CRC: colonoscopy at 40 or 10 years before their diagnosis, every 5 years. Adenoma follow-up: 1–2 small = 7–10 years; advanced or ≥3 = 3 years. FAP: colectomy; Lynch: colonoscopy every 1–2 years from 20–25.

Appendicitis & diverticulitis. Appendicitis: periumbilical pain migrating to RLQ, anorexia, McBurney, Rovsing; CT (ultrasound in children/pregnancy); appendectomy. Diverticulitis: LLQ pain, fever, CT; uncomplicated = outpatient, antibiotics optional in healthy patients; complicated (abscess, perforation) = admit, drain/surgery; colonoscopy 6–8 weeks after to exclude cancer.

Bowel obstruction. SBO: adhesions > hernia; colicky pain, vomiting, distension, air-fluid levels; NG decompression, fluids, surgery for strangulation (fever, peritonitis, lactate). LBO: cancer, volvulus (sigmoid: coffee bean, decompress with sigmoidoscopy). Ogilvie: pseudo-obstruction, neostigmine.

Mesenteric ischemia. Acute: pain out of proportion to exam, AF or atherosclerosis, lactate ↑ → CTA, heparin, embolectomy/resection. Chronic: postprandial pain, weight loss, food fear — revascularize. Ischemic colitis: elderly after hypotension, bloody diarrhea, watershed; supportive.

Anorectal. Hemorrhoids: fiber, sitz baths; banding for internal grade 1–3; thrombosed external = excision within 72 h. Anal fissure: painful bleeding with defecation, posterior midline → topical nitroglycerin/diltiazem; lateral fissures suggest Crohn/HIV. Perianal abscess: I&D; fistula: seton/fistulotomy. Anal cancer: HPV, MSM/HIV.

GI cancers. Esophageal: adenocarcinoma (GERD/Barrett, distal) vs squamous (alcohol/tobacco, proximal). Gastric: H. pylori, Virchow node, Sister Mary Joseph nodule. Pancreatic: painless jaundice, Courvoisier gallbladder, CA 19-9, Trousseau syndrome, new diabetes >50. HCC: cirrhosis + AFP + arterial enhancement. Carcinoid: flushing, diarrhea, 5-HIAA.

Sepsis. qSOFA/SIRS to screen, lactate >2 and hypotension define septic shock. Blood cultures before antibiotics, antibiotics within 1 hour, 30 mL/kg crystalloid, norepinephrine for MAP <65, source control. De-escalate at 48–72 h on cultures.

Empiric antibiotic map. MRSA: vancomycin, linezolid, daptomycin (not for pneumonia), TMP-SMX/doxycycline outpatient. Pseudomonas: pip-tazo, cefepime, meropenem, ciprofloxacin. Anaerobes: metronidazole, pip-tazo, clindamycin. Atypicals: macrolide, doxycycline, FQ. ESBL: carbapenem.

Meningitis. LP before antibiotics unless focal deficit, papilledema, immunocompromise, seizure, altered mental status — then CT first but antibiotics first of all. Bacterial CSF: neutrophils, glucose <40, protein >200. Empiric: ceftriaxone + vancomycin (+ ampicillin if <1 month or >50 for Listeria) + dexamethasone before/with the first dose. Rifampin for contacts of meningococcus.

HIV essentials. Screen everyone 15–65 once; 4th-generation Ag/Ab then HIV RNA. Start ART at diagnosis regardless of CD4. Prophylaxis: CD4 <200 TMP-SMX (PJP), <100 add toxoplasma coverage, <50 MAC no longer routine if on ART. PrEP: tenofovir-emtricitabine daily or cabotegravir injection. PEP within 72 h × 28 days.

Opportunistic infections. PJP: CD4 <200, ↑LDH, ground glass → TMP-SMX + steroids if PaO₂ <70. Toxoplasma: ring-enhancing lesions → pyrimethamine-sulfadiazine. Cryptococcus: CD4 <100, headache, high opening pressure → amphotericin + flucytosine. CMV retinitis: CD4 <50 → ganciclovir. Esophageal candidiasis → fluconazole. Kaposi = HHV-8.

Tuberculosis. IGRA preferred (BCG-vaccinated); TST ≥5 mm HIV/contacts/immunosuppressed, ≥10 mm high-risk, ≥15 mm everyone. Latent: rifampin 4 months. Active: RIPE 2 + RI 4, airborne isolation, DOT. Drug toxicities: INH hepatitis/neuropathy (B6), rifampin orange fluids/CYP induction, ethambutol vision, PZA gout/liver.

Sexually transmitted infections. Gonorrhea: ceftriaxone 500 mg IM (1 g if ≥150 kg); chlamydia: doxycycline 100 mg BID × 7 days (azithromycin 1 g in pregnancy). Test of cure in pregnancy; retest at 3 months; treat partners (EPT). PID: ceftriaxone + doxycycline + metronidazole. Syphilis: benzathine penicillin — 1 dose early, 3 weekly doses late latent; neurosyphilis IV penicillin; desensitize penicillin-allergic pregnant patients.

Genital ulcers & discharge. Painless ulcer = syphilis (chancre) or LGV; painful = HSV (vesicles) or chancroid (ragged, painful nodes). Trichomonas: strawberry cervix, motile trichomonads → metronidazole, treat partner. BV: clue cells, fishy whiff, pH >4.5 → metronidazole. Candida: pseudohyphae → fluconazole.

Urinary tract infection. Uncomplicated cystitis: nitrofurantoin 5 days, TMP-SMX 3 days, fosfomycin single dose. Pyelonephritis: ceftriaxone or FQ (if resistance <10%); admit if unable to take PO, pregnant, obstructed. Asymptomatic bacteriuria treated only in pregnancy and before urologic procedures. Men: 7-day course, evaluate prostate.

Skin & soft tissue. Non-purulent cellulitis (strep): cephalexin. Purulent/abscess (MRSA): I&D ± TMP-SMX or doxycycline. Necrotizing fasciitis: pain out of proportion, crepitus, rapid spread → surgical debridement + broad antibiotics + clindamycin. Animal bite: amoxicillin-clavulanate (Pasteurella); cat scratch: azithromycin. Diabetic foot: probe-to-bone, MRI for osteomyelitis.

Endocarditis. Modified Duke criteria; 3 blood culture sets before antibiotics, TTE then TEE. Native valve/IVDU: vancomycin ± cefepime/gentamicin; prosthetic: add rifampin. Surgery for HF, abscess, persistent bacteremia, large mobile vegetation with emboli. S. bovis = colonoscopy. Prophylaxis: amoxicillin 2 g for high-risk cardiac lesions only.

Tick-borne. Lyme: erythema migrans = treat without testing (doxycycline 10–14 days; amoxicillin in pregnancy/young children); facial palsy, AV block, arthritis later; IV ceftriaxone for carditis with high-grade block or meningitis. RMSF: fever, headache, rash wrists/ankles → palms/soles, thrombocytopenia, hyponatremia — doxycycline immediately, all ages. Anaplasma/Ehrlichia: leukopenia, ↑LFTs — doxycycline. Babesia: hemolysis, Maltese cross — atovaquone + azithromycin.

Influenza & COVID. Influenza: oseltamivir within 48 h (any time if hospitalized/high-risk); vaccinate everyone ≥6 months yearly. COVID-19: nirmatrelvir-ritonavir within 5 days for high-risk outpatients (check interactions); hospitalized hypoxic = dexamethasone ± remdesivir; anticoagulation prophylaxis.

Vaccines — adults. Tdap once then Td/Tdap every 10 years (Tdap each pregnancy 27–36 weeks). Pneumococcal: PCV20 (or PCV21) once at ≥50 or with risk conditions. Zoster: recombinant 2 doses at ≥50. HPV through 26 (shared decision to 45). MMR/varicella/live vaccines never in pregnancy or severe immunosuppression. RSV ≥75 (60–74 with risk), and in pregnancy 32–36 weeks.

Fever in the returned traveler. Malaria until proven otherwise: thick and thin smears × 3, rapid antigen. P. falciparum severe → IV artesunate; uncomplicated → artemether-lumefantrine; P. vivax/ovale add primaquine (check G6PD). Typhoid: fever, relative bradycardia, rose spots → ceftriaxone/azithromycin. Dengue: fever, retro-orbital pain, thrombocytopenia — no NSAIDs, no aspirin.

Hepatitis & bloodborne exposure. Needlestick: wash, baseline HIV/HBV/HCV, HIV PEP within 72 h, HBIG + vaccine if non-immune to hepatitis B; no PEP exists for hepatitis C — test RNA at 4–6 weeks. Anti-HBs ≥10 = immune.

Osteomyelitis & septic joint. Septic arthritis: hot swollen joint → arthrocentesis before antibiotics (WBC >50,000, positive Gram stain); S. aureus most common, gonococcal in sexually active young adults (migratory, tenosynovitis, pustules) — ceftriaxone. Osteomyelitis: MRI, bone biopsy for the organism, 4–6 weeks IV; salmonella in sickle cell, Pseudomonas in puncture wounds through sneakers.

Fungal infections. Histoplasma: Ohio/Mississippi valleys, caves/bird droppings, mediastinal nodes, pancytopenia. Coccidioides: Southwest, erythema nodosum, eosinophilia. Blastomyces: Great Lakes, skin/bone, broad-based budding. Mild-moderate → itraconazole/fluconazole; severe → amphotericin B. Aspergillus: neutropenia, halo sign → voriconazole. Mucor: DKA, black eschar → surgery + amphotericin.

C. difficile. Diarrhea after antibiotics (clindamycin, FQ, cephalosporins) or PPI; test only unformed stool (toxin/PCR). Non-severe and severe: oral vancomycin or fidaxomicin 10 days; fulminant (hypotension, ileus, megacolon): vancomycin PO/PR + IV metronidazole, surgery. Recurrence: fidaxomicin, bezlotoxumab, fecal transplant. Contact precautions, soap and water (alcohol gel fails).

Immunocompromised fever. Febrile neutropenia (ANC <500, T ≥38.3): cultures, then cefepime/pip-tazo/meropenem within an hour; add vancomycin for line infection, MRSA, hypotension, mucositis; antifungal if fever persists 4–7 days. Transplant recipients: CMV at months 1–6, PJP prophylaxis, no live vaccines. Asplenia: encapsulated organisms — vaccinate, treat fever as an emergency.

KDIGO AKI. Cr ↑≥0.3 in 48 h, or ≥1.5× in 7 d, or UO <0.5 mL/kg/h × 6 h. Stage 3 = 3×, Cr ≥4, KRT, anuria 12 h.

Prerenal vs ATN. BUN:Cr >20, FENa <1%, bland urine, improves with volume = prerenal. FENa >2%, muddy casts, no response = ATN.

FENa limits. Invalid on diuretics (use FEUrea <35%). Low-FENa impostors: contrast, rhabdo, hemolysis, hepatorenal, sepsis, early GN.

Sediment. Muddy = ATN. RBC casts = GN. WBC casts = AIN/pyelo. Fatty/Maltese = nephrotic. Envelope oxalate, rhomboid urate, coffin-lid struvite, hexagon cystine.

Dipstick traps. Heme + / RBC − = myoglobin. Protein − / UPCR + / low anion gap = myeloma light chains.

Nephrotic range. >3.5 g/day, albumin <3.5, edema, lipids. Child = steroids (MCD). Adult = biopsy. Membranous = renal vein thrombosis.

RBC casts. Glomerular bleeding = glomerulonephritis. Never benign. Serologies and nephrology the same week.

Complement shortcut. Low C3: PSGN (weeks), lupus (+C4), MPGN/HCV, endocarditis. Normal C3: IgA (days), ANCA, anti-GBM.

Pulmonary-renal. Hemoptysis + RBC casts: send ANCA + anti-GBM, pulse steroids now, plasmapheresis for anti-GBM/hemorrhage.

Hyperkalemia. STABILIZE (calcium; any ECG change or K ≥6.5) → SHIFT (insulin/dextrose, albuterol) → REMOVE (loop, SZC/patiromer, dialysis). Kayexalate is out.

Hyponatremia. Serum osm → urine osm (<100 = intake) → volume + urine Na. SIADH needs normal TSH/cortisol. Saline for hypovolemia; restriction for SIADH.

Sodium speed limit. Severe symptoms: 3% saline 100–150 mL ×3 (+4–6). Chronic: ≤8 mEq/L per 24 h. Overshoot: D5W + desmopressin. Hypernatremia ≤10–12/day.

Anion gap approach. AG = Na − Cl − HCO₃ (+2.5 per g/dL albumin <4). Gap: MUDPILES → osmolar gap. Non-gap: HARDASS → urine anion gap (neg = diarrhea, pos = RTA).

Winter’s formula. Expected PaCO₂ = 1.5 × HCO₃ + 8 ± 2. Outside the range = second disorder.

RTA 1 / 2 / 4. Type 1: urine pH >5.5, low K, stones (Sjögren, amphotericin). Type 2: Fanconi (myeloma, tenofovir). Type 4: high K (diabetes, NSAIDs, ACEi).

Stones. Non-contrast CT; ultrasound in pregnancy (no CT first, no ESWL). ≤10 mm: NSAID + tamsulosin + 14-day reimage. Never restrict calcium.

Infected obstruction. Fever + obstructing stone = IV antibiotics + stent or nephrostomy TODAY. Antibiotics alone fail.

CKD principle. ≥3 months. G 90/60/45/30/15; A 30/300. Four pillars: max ACEi/ARB (Cr ≤30% OK, never two), SGLT2i ≥20, finerenone, GLP-1 RA. Iron before ESA.

AEIOU. Refractory Acidosis, Electrolytes (K), Ingestions (SLIME), Overload, Uremia (pericarditis, encephalopathy). Refractory is the word.

Dialysis & transplant. Fistula first, subclavian never. Catheter fever = cultures, vancomycin, pull the line. No thrill = same-day thrombectomy. BK = reduce; rejection = increase. Azole + tacrolimus = toxicity.

Diabetes numbers. A1c ≥6.5 · FPG ≥126 · OGTT ≥200 · random ≥200 + symptoms. Prediabetes 5.7 / 100 / 140. Screen at 35.

Drug by comorbidity. HF or CKD → SGLT2i. ASCVD or obesity → GLP-1 RA / tirzepatide. A1c >10 or catabolic → insulin. Pioglitazone never in HF.

DKA order. Fluids → K (hold insulin if <3.3) → insulin → dextrose at ~200–250 → stop the drip only after the gap closes with basal overlap.

HHS. Glucose >600, osm >320, pH >7.3, obtunded. Fluids are the treatment.

Morning hyperglycemia. 3 AM low = Somogyi → less insulin. 3 AM normal/high = dawn → more or later basal.

Hypoglycemia. Rule of 15; glucagon if not swallowing; sulfonylurea → admit + octreotide. High insulin + low C-peptide = injected insulin.

TSH first. TSH↑ FT4↓ = Hashimoto. TSH↓ FT4↑ = thyrotoxicosis → RAIU/TRAb. Low/normal TSH + low FT4 = central → cortisol before levothyroxine.

Uptake decides. High uptake = Graves/toxic nodule → thionamide, RAI, surgery. Low uptake = thyroiditis/factitious → NSAID + beta-blocker, no thionamide.

Thyroid emergencies. Storm: thionamide → iodine 1 h later → propranolol → steroids. Myxedema coma: IV T4 + hydrocortisone + passive warming.

Thyroid nodule. TSH low → scan (hot = benign). Normal TSH → ultrasound → FNA ≥1 cm if suspicious. MTC = calcitonin, RET, MEN 2.

Thionamide rules. Methimazole first-line; PTU in the first trimester and storm. Fever + sore throat = stop and CBC. Never RAI in pregnancy.

Adrenal insufficiency. Unstable: draw cortisol/ACTH, give hydrocortisone and saline NOW. Stable: AM cortisol → cosyntropin. ACTH↑ + K↑ + pigment = primary; steroid withdrawal = most common secondary.

Cushing algorithm. Exclude exogenous → screen ×2 (1-mg DST, salivary, urine) → ACTH (low = adrenal; high = pituitary/ectopic → high-dose DST/IPSS) → image last.

Adrenal hypertension. Low K + resistant HTN → aldosterone/renin ratio; AVS before surgery. Paroxysms → metanephrines; alpha before beta before surgery.

Incidentaloma. Two questions: functioning (DST, metanephrines, ARR) and malignant (>4 cm, >10 HU, slow washout).

Calcium / PTH. Ca↑ PTH↑ = primary hyperpara (surgery: symptoms, Ca >1 above normal, <50, eGFR <60, T ≤−2.5, stones; low urine Ca = FHH). Ca↑ PTH↓ = cancer/granuloma/vitamin D.

Severe hypercalcemia. Saline → calcitonin → zoledronate (denosumab if CKD); steroids for lymphoma/granuloma; no thiazides.

Hypocalcemia & bone. Tetany/QT = IV calcium; hypoparathyroidism needs calcitriol. Osteoporosis: T ≤−2.5 or fragility fracture = bisphosphonate (eGFR ≥35), denosumab if not.

Pituitary rule. Prolactinoma = cabergoline (even macro). Everything else = transsphenoidal surgery. Acromegaly: IGF-1 → OGTT → MRI. Apoplexy: steroids first.

Water. DI: dilute urine + high Na; DDAVP response = central. SIADH: urine osm >100, urine Na >30, euvolemic, normal TSH/cortisol; restrict; 3% for seizures; ≤8 in 24 h.

Stroke — first minutes. Last known well, glucose, non-contrast CT to exclude hemorrhage. Alteplase/tenecteplase within 4.5 h if no contraindications (BP <185/110 before lysis); thrombectomy for large-vessel occlusion up to 24 h with perfusion imaging. Permissive hypertension to 220/120 if no lysis. Aspirin after 24 h; DAPT 21 days for minor stroke/TIA.

Stroke by artery. MCA: contralateral face/arm weakness, aphasia (left), neglect (right). ACA: leg weakness, abulia, incontinence. PCA: contralateral homonymous hemianopia with macular sparing. Vertebrobasilar: crossed findings, vertigo, diplopia, dysarthria; locked-in. Lacunar: pure motor or sensory, clumsy hand.

Hemorrhagic stroke. Intracerebral: hypertension, reverse anticoagulation (PCC + vitamin K; idarucizumab; andexanet), SBP 140–160, neurosurgery for cerebellar >3 cm. Subarachnoid: thunderclap headache → CT (LP for xanthochromia if CT negative after 6 h) → CTA; nimodipine, secure the aneurysm, watch for vasospasm days 3–14.

TIA & secondary prevention. ABCD² for risk; MRI, carotid imaging, ECG/monitor for AF, echo. Carotid endarterectomy for symptomatic 70–99% stenosis within 2 weeks. Statin high-intensity, antiplatelet (anticoagulate for AF), BP <130/80, diabetes control, stop smoking.

Seizure workup. First unprovoked seizure: glucose, electrolytes, tox screen, MRI, EEG; treat if abnormal EEG/MRI, nocturnal, or second seizure. Provoked (alcohol withdrawal, hypoglycemia, hyponatremia, drugs) = fix the cause, no long-term AED. Driving restrictions per state. Todd paralysis is transient post-ictal weakness.

Status epilepticus. Seizure >5 min or recurrent without recovery. ABCs, glucose/thiamine, lorazepam IV (midazolam IM if no access) → levetiracetam, fosphenytoin, or valproate → intubate and propofol/midazolam infusion. Eclampsia = magnesium. Isoniazid overdose = pyridoxine.

Antiepileptic pearls. Focal: levetiracetam, lamotrigine, carbamazepine (SJS in HLA-B*1502, hyponatremia). Generalized: valproate (teratogenic, hepatotoxic, pancreatitis, weight), lamotrigine (rash — titrate slowly), levetiracetam (mood). Absence: ethosuximide. Pregnancy: lamotrigine/levetiracetam + folate 4 mg; never valproate.

Headache red flags. SNOOP: systemic symptoms, neurologic deficit, onset sudden, older >50, pattern change. Thunderclap = SAH. New headache >50 with jaw claudication/vision = giant cell arteritis: ESR/CRP, start prednisone before biopsy. Papilledema + obese young woman = idiopathic intracranial hypertension: LP (high opening pressure), acetazolamide, weight loss.

Migraine, tension, cluster. Migraine: unilateral pulsatile, nausea, photophobia, aura; abort with NSAID/triptan (no triptans with CAD/hemiplegic migraine); prevent with propranolol, topiramate, amitriptyline, CGRP antagonists (≥4/month). Tension: bilateral band, NSAIDs. Cluster: unilateral orbital, tearing, rhinorrhea, restless; abort with 100% oxygen/sumatriptan SC, prevent with verapamil.

Multiple sclerosis. Woman 20–40; optic neuritis, INO, Lhermitte, Uhthoff, bladder symptoms. MRI: periventricular ovoid lesions separated in space and time; CSF oligoclonal bands. Acute relapse: high-dose IV methylprednisolone (plasma exchange if refractory). Disease-modifying: interferon, glatiramer, natalizumab (PML/JC virus), ocrelizumab. Spasticity: baclofen.

Parkinson vs mimics. Parkinson: resting tremor, bradykinesia, cogwheel rigidity, asymmetric onset — levodopa/carbidopa (dyskinesias), dopamine agonists (impulse control), MAO-B inhibitors. Drug-induced: symmetric, antipsychotics/metoclopramide. Lewy body: dementia + visual hallucinations + parkinsonism; avoid antipsychotics. Essential tremor: action tremor, better with alcohol — propranolol/primidone. Normal pressure hydrocephalus: wet, wobbly, wacky — LP improves, shunt.

Dementia types. Alzheimer: gradual memory-first, temporoparietal atrophy — cholinesterase inhibitor, memantine. Vascular: stepwise, vascular risk. Frontotemporal: personality/language first, younger. Lewy body: fluctuations, hallucinations, REM sleep disorder. Reversible: B12, TSH, depression, NPH, medications. Delirium is acute and fluctuating with inattention.

Guillain-Barré & myasthenia. GBS: ascending symmetric weakness, areflexia, after Campylobacter/viral illness; CSF albuminocytologic dissociation; monitor FVC/NIF, intubate if FVC <20 mL/kg; IVIG or plasmapheresis, no steroids. Myasthenia: fatigable ptosis/diplopia/bulbar weakness, AChR antibodies, ice-pack test, CT chest for thymoma — pyridostigmine, steroids; crisis = intubate, IVIG/plasmapheresis. Lambert-Eaton: proximal weakness improves with use, small cell lung cancer.

Spinal cord emergencies. Cauda equina: saddle anesthesia, urinary retention with overflow, bilateral leg weakness — emergent MRI and decompression. Cord compression (metastasis, abscess): back pain + weakness + sensory level → dexamethasone, MRI, neurosurgery/radiation. Epidural abscess: fever, back pain, IVDU — MRI, antibiotics, drainage.

Neuropathy patterns. Distal symmetric stocking-glove = diabetes, alcohol, B12 (with dorsal column signs), chemotherapy — gabapentin, duloxetine, foot care. Mononeuropathy: carpal tunnel (median; splint, steroid injection, release), foot drop (peroneal), Bell palsy (whole face including forehead → prednisone within 72 h ± valacyclovir, eye protection). Central facial weakness spares the forehead.

Vertigo. Peripheral: BPPV (seconds, positional, Dix-Hallpike → Epley), vestibular neuritis (days, after URI, unidirectional nystagmus, steroids), Ménière (hours, hearing loss, tinnitus, fullness — salt restriction, diuretic). Central: vertical/direction-changing nystagmus, gait ataxia, other brainstem signs, HINTS exam — MRI for posterior stroke.

Head trauma. Canadian CT Head Rule / PECARN for imaging. Epidural: lucid interval, lens-shaped, middle meningeal artery — emergent evacuation. Subdural: crescent, elderly/alcohol/anticoagulated, can be chronic. Concussion: no same-day return to play, graded return; second-impact syndrome. Elevated ICP: head up, hyperventilate briefly, hypertonic saline/mannitol, neurosurgery.

CNS infections. Bacterial meningitis: ceftriaxone + vancomycin (+ ampicillin for Listeria extremes of age) + dexamethasone; LP unless focal deficit/papilledema/immunocompromised (CT first). HSV encephalitis: fever, temporal lobe, RBCs in CSF → IV acyclovir immediately. Brain abscess: ring-enhancing, from sinus/dental/endocarditis → drain + antibiotics.

ALS & muscle disease. ALS: upper AND lower motor neuron signs (fasciculations + hyperreflexia), no sensory loss, bulbar onset possible; riluzole, edaravone, supportive. Duchenne: boy <5, Gower sign, calf pseudohypertrophy, dystrophin absent, CK ↑↑. Polymyositis/dermatomyositis: proximal weakness, CK ↑, heliotrope rash/Gottron papules — steroids, screen for malignancy.

Coma & brain death. Coma workup: glucose, naloxone, thiamine, CT; pupils (pinpoint = opioids/pontine; fixed dilated = herniation/anticholinergic); posturing (decorticate = above red nucleus, decerebrate = brainstem). Uncal herniation: ipsilateral CN III palsy then contralateral weakness. Brain death: irreversible cause, no confounders, absent brainstem reflexes, positive apnea test.