Chest pain

Start with immediate stability, ACS risk, PE clues, aortic pain features, ECG, troponin timing, and when outpatient workup is no longer safe.

Dyspnea and hypoxemia

Sort airway disease, pneumonia, PE, heart failure, anemia, acidosis, and anxiety by oxygenation, work of breathing, auscultation, and imaging/lab pattern.

Fever and sepsis risk

Identify source, immune status, lactate trend, mental status, perfusion, and need for cultures, broad-spectrum coverage, source control, or ED transfer.

Abdominal and pelvic pain

Screen for pregnancy, peritonitis, torsion, appendicitis, cholecystitis, pancreatitis, bowel obstruction, urinary infection, and GI bleeding.

Diabetes, CKD, and cardiovascular risk

Pair A1c and glucose data with albuminuria, BP, statin need, foot care, vaccine status, kidney trajectory, and medication access.

Asthma, COPD, and sleep-related disease

Track symptom burden, rescue use, exacerbation history, smoking exposure, inhaler technique, nocturnal symptoms, and when to step up maintenance therapy.

Pain, mood, and function

Reassess goals, disability, sleep, bowel effects, substance risk, falls risk, antidepressant response, and whether the diagnosis still explains the current problem.

Transitions of care

Medication reconciliation, pending results, follow-up timing, return precautions, and specialist handoff quality often determine whether chronic care stays stable.

Acute coronary syndrome

Pathophysiology: Plaque rupture or erosion triggers coronary thrombosis and myocardial ischemia, with unstable angina, NSTEMI, or STEMI on the same spectrum.

Diagnosis: Serial ECGs, serial troponins, bedside assessment for ongoing ischemia or shock, and early cardiology/PCI evaluation when risk is elevated.

First-line treatment: Aspirin (Bayer/Ecotrin), nitroglycerin (Nitrostat), oxygen only if hypoxemic, and antithrombotic therapy such as heparin or enoxaparin (Lovenox) when appropriate.

Second-line treatment: Add clopidogrel (Plavix) or ticagrelor (Brilinta), high-intensity statin atorvastatin (Lipitor) or rosuvastatin (Crestor), beta-blocker metoprolol (Lopressor/Toprol XL), and proceed to PCI when indicated.

Atrial fibrillation

Pathophysiology: Disorganized atrial depolarization causes ineffective atrial contraction, stasis, and thromboembolic stroke risk.

Diagnosis: ECG confirmation, then evaluate thyroid function, electrolytes, renal function, echocardiography, and stroke/bleeding risk with CHA2DS2-VASc and HAS-BLED.

First-line treatment: Rate control with metoprolol (Lopressor/Toprol XL) or diltiazem (Cardizem/CD) when blood pressure allows.

Second-line treatment: Anticoagulation with apixaban (Eliquis) or rivaroxaban (Xarelto), and rhythm-control options such as amiodarone (Pacerone/Cordarone) or cardioversion for selected patients.

Heart failure

Pathophysiology: Reduced pump performance or impaired filling leads to neurohormonal activation, sodium retention, pulmonary/systemic congestion, and progressive remodeling.

Diagnosis: BNP or NT-proBNP, echocardiography, chest x-ray, renal function, and volume status assessment; search for ischemia, arrhythmia, valve disease, and precipitating infection.

First-line treatment: Furosemide (Lasix) for congestion plus guideline-directed therapy such as sacubitril/valsartan (Entresto) or lisinopril (Zestril/Prinivil) when tolerated.

Second-line treatment: Add empagliflozin (Jardiance) or dapagliflozin (Farxiga), spironolactone (Aldactone), and carvedilol (Coreg) with close monitoring of BP, renal function, and potassium.

Hypertension

Pathophysiology: Chronic vascular tone, renal sodium handling, sympathetic activation, and endothelial dysfunction sustain elevated blood pressure and end-organ injury risk.

Diagnosis: Repeat correct office BP, home or ambulatory readings when possible, and assess BMP/creatinine, potassium, urine albumin, lipids, and ECG for end-organ disease or secondary causes.

First-line treatment: Lifestyle change plus amlodipine (Norvasc), chlorthalidone (Thalitone), lisinopril (Zestril/Prinivil), or losartan (Cozaar) based on comorbidity and tolerability.

Second-line treatment: Resistant or severe cases may need spironolactone (Aldactone), labetalol (Trandate), or nicardipine (Cardene) if crisis-level management is required.

Asthma exacerbation

Pathophysiology: Bronchial hyperresponsiveness and airway inflammation cause reversible airflow obstruction, mucus plugging, and bronchospasm.

Diagnosis: Clinical severity, pulse oximetry, peak flow when feasible, and exclusion of pneumonia, pneumothorax, or pulmonary edema when the picture is unclear.

First-line treatment: Albuterol (ProAir HFA/Proventil/Ventolin) plus inhaled corticosteroid-formoterol such as budesonide-formoterol (Symbicort) for controller therapy.

Second-line treatment: Prednisone (Deltasone), ipratropium-albuterol (DuoNeb/Combivent), and IV magnesium sulfate for severe attacks or poor bronchodilator response.

COPD exacerbation

Pathophysiology: Chronic airway inflammation, mucus hypersecretion, and small-airway remodeling produce fixed obstruction with acute worsening from infection or irritants.

Diagnosis: Post-bronchodilator spirometry for baseline disease, plus pulse ox, chest x-ray, and blood gas testing when hypercapnia or respiratory failure is suspected.

First-line treatment: Albuterol/ipratropium (Combivent or DuoNeb) and prednisone (Deltasone); add azithromycin (Zithromax) or doxycycline (Vibramycin) when bacterial trigger is likely.

Second-line treatment: Maintenance escalation with tiotropium (Spiriva) or budesonide-formoterol (Symbicort), plus smoking cessation support and oxygen titration when indicated.

Community-acquired pneumonia

Pathophysiology: Bacterial, viral, or atypical pathogens inflame alveoli and impair gas exchange, often after aspiration or viral illness.

Diagnosis: Chest x-ray infiltrate, pulse ox, CBC, and severity scoring such as CURB-65 or PSI; consider viral testing and cultures when severe.

First-line treatment: Amoxicillin/clavulanate (Augmentin) plus azithromycin (Zithromax), or doxycycline (Vibramycin) in selected outpatient cases.

Second-line treatment: Ceftriaxone (Rocephin) plus azithromycin, or levofloxacin (Levaquin) when broader respiratory coverage is clinically appropriate.

Pulmonary embolism

Pathophysiology: Venous thrombus embolizes to the pulmonary arteries, causing dead-space ventilation, hypoxemia, and possible right-heart strain.

Diagnosis: Use Wells/PERC risk assessment, D-dimer when low risk, CT pulmonary angiography or V/Q scanning, and venous duplex when DVT is suspected.

First-line treatment: Apixaban (Eliquis) or rivaroxaban (Xarelto) for stable patients needing anticoagulation.

Second-line treatment: Enoxaparin (Lovenox) or unfractionated heparin for hospitalized patients, with alteplase (Activase) reserved for massive, unstable PE in expert settings.

Type 2 diabetes

Pathophysiology: Insulin resistance, beta-cell dysfunction, hepatic glucose overproduction, and adipose inflammation produce chronic hyperglycemia and vascular injury.

Diagnosis: A1c, fasting plasma glucose, or random glucose with symptoms; assess urine albumin, eGFR, lipids, feet, eyes, and hypoglycemia risk.

First-line treatment: Lifestyle therapy and metformin (Glucophage) when tolerated; semaglutide (Ozempic/Rybelsus) is a strong option when weight or ASCVD risk is a major issue.

Second-line treatment: Empagliflozin (Jardiance), dapagliflozin (Farxiga), tirzepatide (Mounjaro/Zepbound), or insulin glargine (Lantus/Basaglar/Semglee) based on phenotype and control.

DKA and HHS

Pathophysiology: Absolute or relative insulin deficiency causes ketogenesis in DKA or profound hyperosmolar dehydration in HHS.

Diagnosis: Glucose, anion gap, beta-hydroxybutyrate, VBG/ABG, electrolytes, serum osmolality, and a search for the trigger such as infection, missed insulin, or MI.

First-line treatment: IV fluids, regular insulin (Humulin R/Novolin R), and potassium replacement with frequent lab reassessment.

Second-line treatment: Transition to basal-bolus insulin, treat the precipitating illness, and use ICU-level care when hypotension, altered mentation, or severe acidosis is present.

Chronic kidney disease

Pathophysiology: Progressive nephron loss causes hyperfiltration injury, albuminuria, reduced filtration, hypertension, anemia, and mineral-bone complications.

Diagnosis: eGFR trend, urine albumin-creatinine ratio, urinalysis/sediment, creatinine, potassium, bicarbonate, and renal imaging when obstruction is possible.

First-line treatment: Lisinopril (Zestril/Prinivil) or losartan (Cozaar) for albuminuric disease, plus BP, glycemic, and dietary sodium control.

Second-line treatment: Add empagliflozin (Jardiance) or dapagliflozin (Farxiga), finerenone (Kerendia) for diabetic CKD when appropriate, and refer to nephrology for rapid decline or advanced stages.

Hypothyroidism

Pathophysiology: Low thyroid hormone slows metabolism, cardiac output, gut motility, and cognition; Hashimoto disease is a common U.S. cause.

Diagnosis: Elevated TSH with low free T4; TPO antibodies help when autoimmune thyroiditis is suspected.

First-line treatment: Levothyroxine (Synthroid/Levoxyl) with dose adjustment by age, cardiac disease, pregnancy, and TSH response.

Second-line treatment: Address absorption issues and interacting drugs, and use IV levothyroxine for myxedema coma with critical-care support.

Hyperthyroidism

Pathophysiology: Excess thyroid hormone increases adrenergic tone, heat intolerance, tachycardia, and catabolism; Graves disease is the classic autoimmune cause.

Diagnosis: Low TSH with elevated free T4/T3, plus thyroid receptor antibodies or uptake scan when the cause needs clarification.

First-line treatment: Methimazole (Tapazole) for most nonpregnant patients; propranolol (Inderal) can help tremor and tachycardia while control is established.

Second-line treatment: Propylthiouracil for thyroid storm or early pregnancy, with radioactive iodine or surgery for definitive management when medication fails or is unsuitable.

GERD and peptic ulcer disease

Pathophysiology: Reflux from a weak lower esophageal sphincter and acid-peptic injury, often worsened by NSAIDs or Helicobacter pylori.

Diagnosis: Clinical trial of therapy is common; EGD for alarm features, and stool antigen or urea breath testing for H. pylori when ulcer disease is suspected.

First-line treatment: Omeprazole (Prilosec) or pantoprazole (Protonix) plus reflux precautions and NSAID review.

Second-line treatment: Famotidine (Pepcid) or H. pylori eradication regimens using amoxicillin (Amoxil), clarithromycin (Biaxin), metronidazole (Flagyl), bismuth subsalicylate (Pepto-Bismol), and tetracycline (Sumycin) when indicated.

Upper GI bleed

Pathophysiology: Ulcer, erosive disease, varices, or mucosal tears cause hemorrhage with anemia, hemodynamic compromise, and possible aspiration.

Diagnosis: CBC, BUN/creatinine, coagulation studies, stool or emesis evidence of bleeding, and endoscopy to identify the source.

First-line treatment: IV pantoprazole (Protonix), resuscitation, and transfusion or reversal strategies as clinically needed.

Second-line treatment: Octreotide (Sandostatin) plus ceftriaxone (Rocephin) for suspected variceal bleeding, with urgent endoscopic therapy and specialist care.

Appendicitis

Pathophysiology: Appendiceal obstruction leads to bacterial overgrowth, ischemia, transmural inflammation, and perforation risk.

Diagnosis: RLQ pain, migration, leukocytosis, CT abdomen/pelvis in adults, and ultrasound-first strategies in children or pregnancy.

First-line treatment: Ceftriaxone (Rocephin) plus metronidazole (Flagyl) when antibiotics are started before source control.

Second-line treatment: Surgical appendectomy, with broader inpatient coverage if perforation or abscess is present.

Cholecystitis

Pathophysiology: Gallstone obstruction of the cystic duct causes gallbladder inflammation, edema, and possible necrosis.

Diagnosis: RUQ pain, Murphy sign, ultrasound, WBC, bilirubin/LFTs, and HIDA scan when ultrasound is equivocal.

First-line treatment: Ceftriaxone (Rocephin) plus metronidazole (Flagyl), NPO status, IV fluids, and analgesia.

Second-line treatment: Laparoscopic cholecystectomy, with ERCP when common bile duct obstruction or cholangitis is suspected.

Acute pancreatitis

Pathophysiology: Premature pancreatic enzyme activation causes autodigestion, inflammation, and third-spacing; gallstones and alcohol are common triggers.

Diagnosis: Lipase, characteristic abdominal pain, and imaging when diagnosis is uncertain or complications are suspected; check triglycerides and calcium for cause.

First-line treatment: Aggressive IV fluids, analgesia such as hydromorphone (Dilaudid) when needed, and antiemetic ondansetron (Zofran).

Second-line treatment: Treat the underlying cause, advance enteral feeding as tolerated, perform cholecystectomy for gallstone disease, and consider insulin-based strategies for severe hypertriglyceridemia.

Pyelonephritis and complicated UTI

Pathophysiology: Ascending bacterial infection reaches the renal pelvis and parenchyma, producing fever, flank pain, and sepsis risk.

Diagnosis: Urinalysis, urine culture, pregnancy test when relevant, and CT when obstruction, stone, or abscess is a concern.

First-line treatment: Ceftriaxone (Rocephin) followed by culture-guided oral therapy such as TMP-SMX (Bactrim DS) or ciprofloxacin (Cipro) when appropriate.

Second-line treatment: Hospitalize for severe disease and use IV cefepime (Maxipime) or piperacillin-tazobactam (Zosyn) when complicated infection or resistant pathogens are likely.

Cellulitis and abscess

Pathophysiology: Skin barrier disruption allows streptococcal or staphylococcal infection; abscesses add a walled-off purulent collection.

Diagnosis: Clinical exam and bedside ultrasound when abscess is uncertain; consider CBC and blood cultures for systemic illness.

First-line treatment: Cephalexin (Keflex) or dicloxacillin (Dynapen) for nonpurulent cellulitis, with incision and drainage for abscesses.

Second-line treatment: TMP-SMX (Bactrim DS), doxycycline (Vibramycin), clindamycin (Cleocin), or linezolid (Zyvox) when MRSA risk or treatment failure is present.

Gout flare

Pathophysiology: Monosodium urate crystal deposition drives neutrophilic inflammation and intense monoarthritis, often in the first MTP joint.

Diagnosis: Arthrocentesis with crystal analysis when feasible, plus serum urate, inflammatory markers, renal function, and culture if septic arthritis is possible.

First-line treatment: Colchicine (Colcrys/Mitigare) or indomethacin (Indocin) early in the flare if renal/GI status allows.

Second-line treatment: Prednisone (Deltasone) when NSAIDs or colchicine are not suitable, and long-term urate lowering with allopurinol (Zyloprim/Aloprim) or febuxostat (Uloric) to prevent recurrence.

Rheumatoid arthritis

Pathophysiology: Autoimmune synovitis with pannus formation leads to cartilage destruction, erosions, deformity, and extra-articular inflammation.

Diagnosis: Symmetric inflammatory joint exam, ESR/CRP, RF, anti-CCP, and hand/foot imaging; screen hepatitis B/C and TB before advanced immunosuppression.

First-line treatment: Methotrexate (Trexall/Rasuvo) with folic acid is the anchor DMARD for many patients, with naproxen (Aleve/Naprosyn) as temporary symptom support.

Second-line treatment: Hydroxychloroquine (Plaquenil), sulfasalazine (Azulfidine), adalimumab (Humira), or etanercept (Enbrel) when disease remains active or erosive.

Depression and generalized anxiety

Pathophysiology: Mood and anxiety disorders reflect biologic vulnerability, stress-system dysregulation, sleep disturbance, and psychosocial burden that can worsen chronic disease adherence.

Diagnosis: PHQ-9 or GAD-7 screening, suicide risk assessment, substance use review, and medical causes such as thyroid disease, anemia, and medication effects.

First-line treatment: Sertraline (Zoloft) or escitalopram (Lexapro) plus psychotherapy, sleep support, and behavioral activation when appropriate.

Second-line treatment: Bupropion (Wellbutrin XL), duloxetine (Cymbalta), or buspirone (Buspar) based on symptom profile, comorbidity, and tolerability.