NBME Medicine Form 3 - Answers & Explanations

Updated: Feb 25, 2020

1) Vitamin B1 (thiamine) • Wernicke encephalopathy triad: ataxia, ophthalmoplegia, confusion

• Thiamine before glucose

2) Osteosarcoma • Associated with Rb mutation • Periosteal bone reaction - codman triangle

3) Pertussis • Paroxysms of intense cough with posttussive vomiting

4) Enterotoxigenic Escherichia coli

• Travelers diarrhea = ETEC

5) Admit the patient to the hospital

• Stable angina has progressed to unstable angina → admit to hospital (cath lab)

6) Chest tube placement • Complicated parapneumonic effusion ( pH < 7.2, glucose < 60) • Treat with chest tube placement to drain the pus and IV antibiotic

7) Medial degeneration of the aorta • Cystic medial degeneration predisposes to dissection

8) Test for factor VIII inhibitor • During a mixing study, normal plasma is added to plasma from a hemophiliac patient

• Clotting deficiencies should correct (PTT returns to normal)

• Factor inhibitors will not correct (PTT will fail to normalize if factor VIII inhibitor is present)

9) Exercise stress echocardiography • This patient already has an abnormal EKG (LBBB will make EKG difficult to interpret)

• Stress echo should be performed instead (which will likely show areas of hypoperfusion induced by exercise)

10) Bromocriptine therapy • Dopamine agonists inhibit prolactin secretion

11) Impaired DNA synthesis • Megaloblastic anemia (impaired DNA synthesis d/t lack of B9 or B12)

12) Anaphylactic shock • Likely due to a food allergy at the restaurant

• Diffuse bronchospasm, hypotension, tachypnea, tachycardia = shock

13) Pericarditis • Lupus is associated with serositis (eg, pericarditis) • Pain in pericarditis is worsened with inspiration (pleuritic) and relieved by leaning forward

14) Labyrinthitis • Acute onset of vertigo with nausea, vomiting and gait disturbance

• Distortion of light reflex off tympanic membrane due to ear fullness

15) Sclerosing cholangitis • PSC is associated with Ulcerative Colitis

• Direct hyperbilirubinemia

16) Chronic hepatitis C • Blood products weren’t screened for HCV until 1992 • HCV is more likely to become a chronic infection (~75%); HBV rarely develops into a chronic infection (~5%)

17) Lung abscess • Cavitary lesion with air fluid level suggests abscess

• Alcoholics → ↑ risk of aspiration pneumonia

18) Serum insulin-like growth factor 1 • IGF-1 mediates most effects of GH - preferred initial test for Acromegaly

• GH levels have wide fluctuations and are not sensitive

19) Ceftriaxone • Numerous gram-positive diplococci = strep pneumo

• Treat with 3rd generation cephalosporin

20) Infection of the joint secondary to disseminated Neisseria gonorrhoeae

• Purulent mono arthritis and/or triad of polyarthralgias, tenosynovitis, and vesiculopustular skin rash

21) Mild cognitive impairment

• MMSE < 24 is suggestive of dementia or delirium

• This patient is able to live independently (drive alone without getting lost, manage his finance) - this with old age is suggestive of mild cognitive impairment

22) Nephrotic syndrome • Decreased protein and edema are consistent with nephrotic syndrome

• Patient is previously health - unlikely that cirrhosis or malnutrition manifests within a 2 week period

23) Myocardial infarction • EKG is consistent with STEMI • Tamponade EKG shows low-voltage QRS with electrical alternans

24) Type 2 diabetes mellitus • HTN + BMI of 32 → ↑ risk of diabetes

25) Administration of warfarin • DVT prophylaxis with LMWH/Heparin (second line option is warfarin)

26) Primary metabolic acidosis • Cardiogenic shock → hypoperfusion → hypoxemia → ↓ oxidative phosphorylation → lactic acidosis → metabolic acidosis

27) Colonoscopy • Patient FOBT in patients > 50 → colonoscopy; >40 → sigmoidoscopy; <40 → anoscopy

28) Intravenous ceftriaxone • Cant use oral antibiotics since this patient is vomiting (or if patient is elderly or septic)

• IV fluoroquinolone, aminoglycoside, or cephalosporins can be used • Most hospitalized patients can be transitioned to oral antibiotics (eg, TMP-SMX or oral fluoroquinolone) if symptoms are improved at 48hrs

29) High-output heart failure • Blood loss (positive FOBT) and severe anemia (hemoglobin is 5) → high-output heart failure (ejection fraction is 70%)

30) Pulmonary edema • Long standing poorly controlled HTN → LV failure with pulmonary edema

• ↑ LA pressure → cephalization of pulmonary vessels

31) rare WBC, eosinophils • Nafcicillin (penicillin) → tubulointerstitial nephritis

32) Accumulation of β-hydroxybutyric acid

• Anion gap = 22

• DKA has increased AG, HHS has normal AG

• Rapid breathing = Kussmaul breathing

33) Acute urethral obstruction • No urine output = mechanical pathology; decreased urine output = functional renal pathology

34) Synchronized cardioversion • Wide complex tachycardia with hemodynamic instability should be treated with synchronized cardioversion

35) 0.9% Saline • Initial treatment for hypercalcemia is normal saline & calcitonin (short term); Bisphosphonates are used for long term treatment

36) Repeat measurement of serum cholesterol concentration in 5 years • Everyone should be screened with fasting lipid profile every 5 years beginning at 20 years old

37) Rapid infusion of 0.9% isotonic saline

• Fluid resuscitation to treat hemodynamic instability, then emergent EGD

38) Radial nerve injury • Humeral fracture - “ARM”

• Proximal humeral fracture → Axillary nerve injury • Mid shaft humeral fracture → Radial nerve injury → wrist drop

• Distal humeral fracture → Median nerve injury

39) Oral ibuprofen • This questions points to rheumatoid arthritis (RA): pain being worst in the morning, ↑ ESR, symmetric swelling, systemic symptoms (fatigue), subchondral cysts and osteopenia

• First-line therapy for RA is NSAIDs (eg, ibuprofen)

40) Asbestosis • Associated with ship building or shipyard work • Calcified pleural plaques are pathognomonic for asbestosis

• Malignancy effusion → low glucose

41) Activation of mast cells • Asthma exacerbated by smoke • “end expiratory wheeze”, “CXR show no abnormalities” = asthma