ABIM Internal Medicine cheat sheet

Anaphylaxis: give IM epinephrine 0.3–0.5 mg of 1 mg/mL solution into the anterolateral thigh; repeat every 5–15 minutes as needed; antihistamines and corticosteroids never delay epinephrine.

Hypersensitivity types: type I is IgE/mast-cell mediated; type II is antibody-mediated; type III is immune-complex mediated; type IV is T-cell mediated and delayed.

Hereditary angioedema: C1 inhibitor deficiency causes recurrent nonpruritic swelling without urticaria; C4 is low, tryptase is normal, and epinephrine or antihistamines do not relieve attacks.

Chronic urticaria lasting more than 6 weeks: use second-generation H1 antihistamines first, uptitrate as needed, add omalizumab if uncontrolled, and avoid chronic systemic corticosteroids.

Common variable immunodeficiency: low IgG with poor vaccine response and recurrent sinopulmonary infections; treat with immunoglobulin replacement.

Allergic rhinitis: intranasal corticosteroids are the most effective single agent; add an antihistamine for sneezing/itch, and immunotherapy can modify the disease course.

Penicillin allergy: skin testing has a high negative predictive value; a negative test permits beta-lactam use, while desensitization is used for immediate reactions when no alternative exists.

STEMI: primary PCI is preferred within 90 minutes of first medical contact; fibrinolysis within 30 minutes is used when PCI cannot be achieved within 120 minutes and symptoms are under 12 hours.

HFrEF: guideline therapy includes an ARNI or ACE inhibitor/ARB, an evidence-based beta-blocker, a mineralocorticoid receptor antagonist, and an SGLT2 inhibitor.

Atrial fibrillation anticoagulation: use CHA2DS2-VASc to estimate stroke risk; DOACs are preferred over warfarin except with mechanical valves or moderate-to-severe mitral stenosis.

Acute decompensated heart failure: IV loop diuretics are first-line; add nitrates for hypertensive pulmonary edema; do not initiate beta-blockers during acute decompensation.

Severe aortic stenosis: aortic valve area below 1.0 cm2, mean gradient above 40 mm Hg, or peak velocity above 4 m/s; symptoms warrant valve intervention.

Pericarditis: ECG shows diffuse ST elevation and PR depression; treat with NSAIDs plus colchicine.

Hypertrophic cardiomyopathy: avoid volume depletion and vasodilators; beta-blockers are first-line; ICD is indicated for high sudden-death risk.

DKA: begin IV insulin infusion after potassium is above 3.3 mEq/L; add dextrose when glucose falls below 200–250 mg/dL while continuing insulin until ketoacidosis resolves.

Thyroid storm: treat with beta-blockade, a thionamide such as PTU, iodine at least 1 hour after the thionamide, glucocorticoids, and supportive care.

Myxedema coma: give IV levothyroxine plus stress-dose hydrocortisone until adrenal insufficiency is excluded.

Primary hypothyroidism: TSH is elevated and free T4 is low; start levothyroxine and recheck TSH in 6–8 weeks.

Adrenal crisis: give hydrocortisone 100 mg IV then 50 mg every 6 hours plus isotonic saline without waiting for confirmatory tests.

Hypercalcemia: corrected calcium = measured calcium + 0.8 × (4.0 − albumin); primary hyperparathyroidism causes high PTH, while malignancy usually causes low PTH.

Diabetes diagnosis: A1c ≥6.5%, fasting glucose ≥126 mg/dL, or 2-hour glucose ≥200 mg/dL; prediabetes A1c is 5.7–6.4%.

SIADH: euvolemic hypotonic hyponatremia with urine osmolality >100 mOsm/kg and urine sodium >40 mEq/L; fluid restriction is first-line.

Upper GI bleeding: give IV proton-pump inhibitor and perform endoscopy within 24 hours; for suspected variceal bleeding add octreotide and ceftriaxone.

Acute pancreatitis: diagnosis requires 2 of 3 features-characteristic pain, lipase >3 times upper limit of normal, and imaging findings; give early aggressive IV fluids.

Ascites: serum-ascites albumin gradient ≥1.1 g/dL indicates portal hypertension; first-line therapy is spironolactone plus furosemide with sodium restriction.

Spontaneous bacterial peritonitis: ascitic fluid polymorphonuclear cells ≥250/mm3; treat with IV cefotaxime and add albumin for renal impairment or bilirubin >4 mg/dL.

Hepatitis B serology: HBsAg with anti-HBc IgM indicates acute infection; isolated anti-HBs indicates vaccination or resolved immunity.

Clostridioides difficile: watery diarrhea with positive toxin or NAAT; treat with oral vancomycin or fidaxomicin and avoid antiperistaltic agents.

Celiac disease: IgA tissue transglutaminase is the preferred screen; IgA deficiency can cause a false-negative result; confirm with duodenal biopsy.

Inflammatory bowel disease: ulcerative colitis is continuous from the rectum; Crohn disease is transmural with skip lesions; severe colitis warrants systemic corticosteroids.

Colorectal cancer screening: USPSTF recommends screening adults aged 45–75 years.

Breast cancer screening: USPSTF recommends biennial mammography for women aged 40–74 years.

Cervical cancer screening: ages 21–29 cytology every 3 years; ages 30–65 HPV testing every 5 years, co-testing every 5 years, or cytology every 3 years.

Osteoporosis: DEXA T-score ≤−2.5 defines osteoporosis; treatment includes bisphosphonates plus adequate calcium and vitamin D.

Delirium: acute fluctuating inattention and awareness; identify and treat the cause, avoid restraints, and reserve antipsychotics for severe distress.

Depression: screen with PHQ-2 and confirm with PHQ-9; first-line treatment is psychotherapy or an SSRI.

Melanoma: use ABCDE-asymmetry, border irregularity, color variation, diameter >6 mm, and evolving lesion.

Preeclampsia: new hypertension after 20 weeks with proteinuria or organ dysfunction; magnesium sulfate prevents seizures in severe disease.

Preventive statin therapy: discuss a statin when 10-year ASCVD risk is ≥7.5%; aspirin is not routinely used for primary prevention.

Iron deficiency: ferritin <30 ng/mL is diagnostic; with inflammation, ferritin <100 ng/mL plus transferrin saturation <20% suggests iron deficiency.

Vitamin B12 deficiency: macrocytic anemia with elevated methylmalonic acid and homocysteine; treat parenterally for pernicious anemia or ileal disease.

Heparin-induced thrombocytopenia: platelets fall by >50% 5–10 days after heparin exposure and thrombosis may occur; stop heparin and start argatroban or bivalirudin.

Thrombotic thrombocytopenic purpura: microangiopathic hemolytic anemia, thrombocytopenia, neurologic or renal findings, and ADAMTS13 <10%; urgent plasma exchange is required.

Disseminated intravascular coagulation: prolonged PT/PTT, low fibrinogen, high D-dimer, and schistocytes; treat the underlying cause.

Sickle cell vaso-occlusive crisis: hydration, opioid analgesia, and oxygen only if hypoxemic; hydroxyurea reduces crisis frequency.

Neutropenic fever: fever ≥38.3°C once or ≥38.0°C sustained with ANC <500/mcL; give empiric anti-pseudomonal beta-lactam within 1 hour.

Polycythemia vera: JAK2 mutation with low erythropoietin; treat with therapeutic phlebotomy and aspirin for thrombosis risk.

Septic shock: obtain cultures, measure lactate, and give broad-spectrum antibiotics within 1 hour; give 30 mL/kg crystalloid for hypotension or lactate ≥4 mmol/L.

Community-acquired pneumonia: outpatients without comorbidity can receive amoxicillin or doxycycline; inpatients often receive ceftriaxone plus azithromycin.

Latent tuberculosis: positive interferon-gamma release assay or tuberculin skin test without active disease; treat with rifampin for 4 months or isoniazid for 9 months.

HIV: screen all adults aged 13–64; start antiretroviral therapy regardless of CD4 count; give Pneumocystis pneumonia prophylaxis when CD4 <200/mcL.

Bacterial meningitis: start vancomycin plus ceftriaxone immediately; add ampicillin for age >50 or immunocompromise; give dexamethasone before or with the first antibiotic dose.

Uncomplicated cystitis: nitrofurantoin for 5 days is first-line; avoid fluoroquinolones as initial therapy.

Cellulitis: typically caused by beta-hemolytic streptococci or Staphylococcus aureus; treat with cephalexin and add MRSA coverage for purulent infection.

Infective endocarditis: obtain 3 sets of blood cultures before antibiotics; native-valve empiric therapy often uses vancomycin plus ceftriaxone.

AKI KDIGO: serum creatinine rise ≥0.3 mg/dL within 48 hours, increase to ≥1.5 times baseline within 7 days, or urine output <0.5 mL/kg/hour for 6 hours.

Prerenal AKI: BUN/Cr >20, FENa <1%, and urine sodium <20 mEq/L; ATN shows FENa >2% and muddy-brown casts.

Hyperkalemia: obtain ECG; give calcium gluconate for instability, then insulin/glucose and albuterol; dialysis is used for refractory cases.

Hyponatremia: assess volume status and osmolality; severe neurologic symptoms require hypertonic 3% saline with controlled correction.

CKD: eGFR <60 mL/min/1.73 m2 for >3 months; use ACE inhibitor/ARB for proteinuria and SGLT2 inhibitor for albuminuric CKD.

Nephrotic syndrome: proteinuria >3.5 g/day with hypoalbuminemia, edema, and hyperlipidemia; minimal change disease is steroid-responsive.

Nephritic syndrome: hematuria, RBC casts, hypertension, and oliguria; post-streptococcal glomerulonephritis causes low C3.

Dialysis indications: AEIOU-acidosis, electrolyte disturbance, intoxication, volume overload, and uremia.

Contrast-associated AKI: use isotonic saline hydration and the lowest volume of iso-osmolar contrast; bicarbonate and N-acetylcysteine are not proven.

Ischemic stroke: CT excludes hemorrhage; IV thrombolysis is given within 4.5 hours, and thrombectomy is used up to 24 hours in selected patients; BP must be <185/110 before thrombolysis.

Status epilepticus: give a benzodiazepine first, then levetiracetam, fosphenytoin, or valproate if seizures continue; intubate for refractory status.

Migraine: triptans are acute therapy; preventive options include beta-blockers, topiramate, and amitriptyline.

Parkinson disease: bradykinesia plus rigidity or tremor; levodopa/carbidopa is most effective; avoid metoclopramide and dopamine-blocking antipsychotics.

Multiple sclerosis: demyelinating disease diagnosed by MRI dissemination in space and time; IV corticosteroids treat acute relapses, and disease-modifying therapy reduces relapses.

Myasthenia gravis: fatigable ptosis, diplopia, or bulbar weakness; anti-acetylcholine receptor antibodies are common; pyridostigmine is symptomatic therapy, and crisis requires IVIG or plasma exchange.

Bell palsy: give corticosteroids within 72 hours and protect the eye; antivirals are optional.

Subarachnoid hemorrhage: thunderclap headache; CT is first, followed by lumbar puncture if CT is negative; nimodipine reduces vasospasm.

Tumor lysis syndrome: hyperkalemia, hyperphosphatemia, hyperuricemia, and hypocalcemia; treat with aggressive hydration and allopurinol or rasburicase.

Spinal cord compression: back pain with weakness, sensory loss, or bowel/bladder dysfunction in cancer; give dexamethasone immediately and obtain MRI.

Superior vena cava syndrome: facial swelling, distended neck veins, and dyspnea; obtain CT and treat with steroids plus stent or radiation.

Malignant hypercalcemia: give IV fluids, a bisphosphonate such as zoledronic acid, and calcitonin for rapid control.

Small cell lung cancer: often paraneoplastic with SIADH or Cushing syndrome; extensive disease is treated with platinum plus etoposide.

Non-small cell lung cancer: test for EGFR, ALK, and PD-L1; targeted therapy is used for actionable drivers.

Breast cancer: determine ER, PR, and HER2 status; HER2-positive disease receives trastuzumab-based therapy.

Prostate cancer: PSA screening requires shared decision-making; Gleason score determines risk group.

COPD: post-bronchodilator FEV1/FVC <0.70 confirms persistent airflow obstruction; long-acting bronchodilators are mainstay, and oxygen is indicated for PaO2 ≤55 mm Hg or SpO2 ≤88%.

Asthma: reversible airflow obstruction; inhaled corticosteroids are used for persistent disease, SABA is rescue therapy, and systemic steroids treat severe exacerbations.

Pulmonary embolism: use Wells score or PERC to estimate pretest probability; CTPA is diagnostic; anticoagulate, and give thrombolysis for massive PE with hypotension.

ARDS: Berlin criteria are acute onset, bilateral opacities, PaO2/FiO2 ≤300, and not primarily cardiac; use low tidal volume ventilation at 6 mL/kg predicted body weight.

Pleural effusion: Light criteria define exudate when protein ratio >0.5, LDH ratio >0.6, or pleural LDH >2/3 upper normal serum limit.

Obstructive sleep apnea: STOP-BANG identifies risk; polysomnography confirms diagnosis; CPAP is first-line therapy.

Pulmonary hypertension: mean pulmonary artery pressure >20 mm Hg at rest; classify by group and treat the underlying cause.

Gout: acute flares are treated with NSAIDs, colchicine, or corticosteroids; urate-lowering therapy is indicated for tophi, frequent flares, or CKD, with allopurinol titrated to urate <6 mg/dL.

Rheumatoid arthritis: symmetric small-joint synovitis with anti-CCP; methotrexate is first-line disease-modifying therapy, and treatment targets remission.

Systemic lupus erythematosus: ANA is sensitive; anti-dsDNA and anti-Smith are specific; hydroxychloroquine is used in most patients, and lupus nephritis requires biopsy.

Giant cell arteritis: age >50 with headache, jaw claudication, visual symptoms, and elevated ESR; start high-dose corticosteroids immediately and confirm with temporal artery biopsy or ultrasound.

Polymyalgia rheumatica: shoulder and hip girdle stiffness with elevated ESR and rapid response to low-dose prednisone.

Osteoarthritis: weight loss and exercise are first-line; acetaminophen or NSAIDs treat pain, and intra-articular corticosteroids are used for flares.

Septic arthritis: acute monoarthritis with fever; aspirate for Gram stain and culture, start IV antibiotics, and drain the joint promptly.

Ankylosing spondylitis: sacroiliitis with HLA-B27; TNF inhibitors are used for persistent axial disease.

Compartment syndrome: pain out of proportion and pain with passive stretch; emergent fasciotomy is required.