NBME Medicine Form 1 - Answers & Explanations

Updated: Nov 16, 2019

1) Paradoxical pulse • Becks triad → cardiac tamponade • Pulsus paradoxus - increased VR with inspiration → RV pushing against IV septum → impairs LV filling and SV → ↓ amplitude of SBP by > 10 mmHg

2) Biopsy and culture of lung mass • Invasive aspergillosis (↑ eosinophils)

• Steroid use → ↑ PMNs

3) Sarcoidosis • 75% of cases occur in patients < 40 yo • CXR/CT shows hilar and mediastinal adenopathy • Associated w/ uveitis (may also see erythema nodosum)

• PFTs show ↓ DLCO

4) Rhabdomyolysis • Associated with alcoholism • “positive blood by dipstick” without RBC’s = myoglobin

5) Recurrent pulmonary emboli

• V/Q defect w/ no ventilation abnormalities → PE • Lack of JVD and clear auscultation of lungs help r/o cardiac insufficiency

• Lack of chest pain helps r/o coronary ischemia

6) IV acyclovir therapy • Chemo → Immunocompromised → Shingles (VZV)

7) Gluten-sensitive enteropathy • Celiac disease → malabsorption and steatorrhea (foul-smelling) • IgA anti-transglutaminase, anti-endomysial, anti-deaminated gliadin antibodies

• Affects duodenum → ↓ Fe absorption → Iron deficient anemia

8) Gilbert syndrome • Mild jaundice without other sxs following stress (eg, surgery)

9) Acute hepatitis • Hyperbilirubinemia → jaundice and pruritis • Acute hepatitis → mild/moderate aminotransferase elevation (<500 U/L)

10) Osmotic diuresis • Hyperosmotic hyperglycemic state (HHS)

• Hyperglycemia → osmotic diuresis → intravascular volume depletion

• Blood glucose in HHA is usually >600; DKA is usually <600

11) ACTH stimulation test • Primary adrenal insufficiency • Loss of mineralocorticoid production → ↓ BP, ↓ Na, ↑ K

• Eosinophilia is common but nonspecific

12) IgA deficiency • Anaphylactic blood transfusion rxn are caused by recipient anti-IgA antibodies

• IgA lines mucosal surface; lack of IgA → ↑ infections

13) Measurement of serum cholesterol concentration

• The USPSTF recommends cholesterol screening q5y in men at age 35

• If at increased risk of coronary heart disease, begin screening in men age 20-35

14) Barium swallow

• Male, >60, dysphagia, regurgitation → Zenker diverticulum

15) Systemic broad-spectrum antibiotic therapy

• Septic shock should be tx with IV antibiotics (broad spectrum)

• Vasopressors can be used if hypotension persists despite aggressive IVF resuscitation

16) Administration of isoniazid

• PPD ≥ 10mm of induration in a healthcare worker is considered positive

• Absence of active TB (normal CXR, no sxs) + ⊕ PPD → latent TB tx

• 9 months of isoniazid and pyridoxine

17) Activation of the renin-renin-angiotensin system

• Fibromuscular dysplasia → ↓ perfusion to kidney → ↑ RAAS

18) Hypogonadotropic hypogonadism (Kallmann syndrome) • Defective migration of GnRH neurons → failure to complete puberty

• Associated with hyposmia/anosmia

19) 0%

• Sickle cell s autosomal recessive

• The mother has HbA (α2β2) → potential chance of their child having sickle cell trait, but impossible for their child to have sickle cell disease

20) Ciprofloxacin

• Fever, chills, tender prostate → prostatitis • Antibiotic penetration of the prostate is difficult

• Tx: TMP-SMX or Quinolone

21) Warfarin

• Chronic AFib in patients >60 yo should receive anticoagulation (warfarin)

• Patients <60 yo with ‘lone’ AFib have lower risk of embolization and therefore do not require anticoagulation (although aspirin should be given)

22) Oral acyclovir therapy

• Herpetic whitlow (HSV) - group of vesicles on the hand with erythematous base

23) Do not administer rt-PA despite the son’s insistence, because it is medically contraindicated in this setting

• Healthcare proxies make choices based upon non-maleficent care options

24) Ventricles

• Wide QRS and absent p wave

• Premature wide complexes come from the ventricles

• Don't use normal conduction system - APs must travel from myocyte to myocyte, which is much slower → wide QRS complex)

• If the complex is narrow then the impulse is coming from the atria above the AVN

25) Vancomycin • Source of infection is unknown → empiric ceftazidime and vancomycin to cover possible MRSA infection

26) Fat embolism

• Long bone fracture → fat emboli • Triad: hypoxia, petechial rash, neurologic abnormalities

27) Renal tubule • Tubulointerstitial nephritis is associated with eosinophil pyuria, as well as cephalosporins (this patient is on cefazolin)

28) Oral corticosteroids • Management of asthma exacerbation includes oxygen, oral steroids, and nebulizer (albuterol/ipratropium)

29) Intravenous 0.9% saline • Hypovolemic hypernatremia - hypotension, dry mucous membrane, tachycardia

• Asymptomatic - tx with 5% dextrose • Symptomatic - tx with 0.9% until euvolemic, then switch to 5% dextrose

30) Observation only

• A stable mole with no changes over the last 15 years is most likely benign.

• Findings concerning for malignancy include asymmetry, irregular border, and change in size and appearance over time

• This patients lymph node (LN) has normal features: soft, mobile, <2 cm (Abnormal LN features include firm or hard, immobile, and size >2 cm)

31) Aortic valve replacement

• Patients with symptomatic aortic stenosis should undergo valve replacement

32) Ingested spores • Recent use of antibiotics + psuedomebranes → C. difficile

• Enters the human body via ingestion of spores

33) Obtain the CT scan without consent

• Emergency situation; beneficence and non maleficence

34) Pyelonephritis • CVA tenderness, fever, chills → pyelonephritis

• Leukocytosis with left shift

35) Chronic volumes overload on the right ventricle

• Wide split fixed S2 = ASD → left to right shunt → ↑ RA and RV volume

36) Bone metastasis • Bone pain in patients >50 yo, without other sxs, is most likely d/t metastasis

• Bone scans detect osteoblastic activity (eg, metastasis or Paget disease)

37) Cardiomyopathy

• Signs and sxs of CHF, Cardiomegaly on CXR

• This patient has left and right sided pathology (ASD, chronic PE, Cor pulmonale → right sides heart failure only)

38) Drug allergy • Drug fever is a dx of exclusion • Often presents 1 week to 1 month after initiation of the drug

• Floroquinolones are associated with drug fever

39) Malignant transformation of epithelial cells

• 56 pack years + painless hematuria → Urothelial (transitional cell) carcinoma

40) Measurement of serum ferritin concentration • Hemochromatosis presents after the age of 40 • Triad of cirrhosis, diabetes mellitus, skin pigmentation

• Also causes arthropathy, hypogonadism, and cardiomyopathy

41) Mineralocorticoid excess • Primary hyperaldosteronism → hypokalemia, ↑ BP

• Aldosterone escape → normal Na levels

42) Increased bone turnover • Paget disease presents with focal pain, tenderness and warmth (hyperemia)

• Associated with bowing deformities • ALP may or may not be ↑ depending on the current phase of Paget disease

43) Administer 50% dextrose in water • Hypoglycemia → transient LOC (typically in insulin dependent diabetes)

44) Weight reduction • Non-inflammatory mono arthritis w/ WBC <2000 → Osteoarthritis

• Risk factors: age, obesity, trauma

45) Lactic acid • Ruptured appendicitis → hypovolemic shock → impaired tissue perfusion → tissue hypoxia → switch to anaerobic metabolism → lactic acidosis (elevated AG metabolic acidosis)

46) CT scan of the abdomen

• Previous cholecystectomy means that obstruction is unlikely to be a stone

• Old age + ‘double-duct’ sign → pancreatic cancer

• CT should be used when U/S is inconclusive

47) Aortic dissection • Severe pain, diastolic murmur (aortic regurgitation in proximal dissection)

48) Alveolar-arteriolar mismatch • CHF → pulmonary edema limiting gas exchange → A-a mismatch

• Low CO2 and respiratory alkalosis help differentiate from COPD exacerbation, which causes high CO2 and respiratory acidosis

49) Amyotrophic lateral sclerosis • Presence of both upper (spasticity, hyperreflexia, babinski) and lower (atrophy, fasciculations [muscle twitching]) motor neuron lesions

50) Indomethacin • NSAIDs are first line tx for acute gout • Prednisone is only given if there is no response to NSAIDs

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