Official Step 2 CK Practice Exam - Answers & Explanations

Updated: Aug 28, 2020

Practice exam: http://orientation.nbme.org/Launch/USMLE/STPF1

Please note: The HY Medicine is in no way affiliated with the Federation of State

Medical Boards (FSMB) or the National Board of Medical Examiners® (NBME®)


BLOCK 1


1) Alcohol

• Alcohol → ↑ GGT


2) Herpes Zoster • Vesicular rash in a dermatomal distribution • Shingles can be triggered by severe physical stress (eg, chemotherapy) or immunosuppressed states


3) Haemophilus ducreyi • Multiple ulcers with gray/yellow exudate • Chancroid (H ducreyi) and HSV present with painful initial lesions; Granuloma inguinal (Klebsiella granulomatis), Syphilis (Treponemia pallidum), and Lymphogranuloma venereum (C trachomatis) do not have initial painful lesions


4) Excision of the lesion

• This lesion is concerning for cancer and should be completely excised


5) Adverse effects of medication • ACEi (eg, lisinopril) and potassium-sparing diuretics (eg, spironolactone) → hyperkalemia


6) Compression of the lateral femoral cutaneous nerve • Lateral femoral cutaneous nerve provides sensory innervation to the anterior and lateral thigh • Hematoma → compression of the lateral femoral cutaneous nerve → ↓ sensation (hematoma doesn’t directly cause ↓ sensation, but rather through nerve compression)


7) Reassurance • Moro reflex is normal until ~4 months


8) Ultrasonography of the upper abdomen • Intermittent, acute RUQ pain in an obese woman = biliary colic • RUQ ultrasound → visualization of biliary stones; HIDA scan is useful when U/S findings are equivocal • Tx: Elective cholecystectomy


9) Arteriovenous fistula

• Post-traumatic AV fistula → continuous bruit (→ buzzing sensation) + palpable thrill + no mass

• DDx: pseudoaneurysm → systolic bruit + pulsatile mass


10) Ultrasonography

• Ultrasound should be used to accurately assess this woman gestational age (LMP unknown)

• The most common cause of abnormal MSAFP is incorrect dating (ie, underestimation of gestational age)


11) Thrombotic thrombocytopenic purpura • Pentad: fever, microangiopathic hemolytic anemia (→ ↑ LDH & fragmented erythrocytes), thrombocytopenia (→ scattered petechiae), acute kidney injury (↑ BUN & creatinine), neurologic symptoms (confusion)


12) Systemic lupus erythematosus • ⊕ ANA (sensitive) and ⊕ anti-DNA (specific) = SLE


13) Measurement of serum insulin and C-peptide concentrations • Hypoglycemia in a nurse is suspicious for factitious disorder imposed on self (aka Munchausen syndrome)

• Exogenous insulin use: ↑ serum insulin, ↓ C-peptide

• C-peptide level helps distinguish exogenous insulin use from insulinoma (high C- peptide)


14) Exercise and weight reduction program

• In obese individuals, the most effective non-pharmacologic approach to reduce blood pressure is weight loss

• Urinalysis and renal U/S exclude renal HTN (eg, fibromuscular dysplasia, Conn syndrome)


15) Mastoiditis

• Complication of acute otitis media → otalgia, deviation of ear, inflammation of mastoid

• Tx: IV antibiotics


16) Vasculitis • Granulomatosis with polyangiitis (Wegener) → upper respiratory tract (eg, sinus congestion), lower respiratory tract (eg, cough + sputum), and renal (eg, hematuria, ↑ BUN & creatinine) involvement

• ⊕ c-ANCA • Tx: cyclophosphamide, corticosteroids


17) Decreased gluconeogenesis • Von Gierke disease: deficiency of glucose-6-phosphatase → inability of liver to regulate blood glucose → hepatomegaly + severe fasting hypoglycemia

18) Ventilation-perfusion mismatch • Pulmonary embolism → pleuritic chest pain, shortness of breath, tachypnea


19) Endometriosis

• Dysmenorrhea + Infertility

• Presence of secretory endometrium rules out anovulation; Progesterone (secreted by the corpus luteum during ovulatory cycles) → differentiation of proliferative endometrium into secretory endometrium


20) Decreasing myocardial contractility • β-bockers (and ynon-dihydropyradine CCBs) → ↓ contractility & heart rate → ↓ myocardial O2 demand



21) Alcohol withdrawal

• Agitation, tremulousness, uncooperative, and lack of orientation after an unexpected admission to the hospital (unanticipated detox) • DDx: fate embolism → respiratory distress, petechial rash, neurologic dysfunction


22) Dermatomysositis • Proximal muscle weakness + Gottron papules (flat-topped red papules over all knuckles) + heliotrope rash (purple-red discoloration over the eyelids)


23) Metabolic acidosis, respiratory compensation • ↓ pH = acidosis • ↓ HCO3− = metabolic acidosis, ↓ CO2 = respiratory compensation

Winter formula → predicted respiratory compensation


24) Cryptosporidium parvumCryptosporidium → severe watery diarrhea + weight loss • Mycobacterium avium complex and CMV diarrhea present once CD4 <50


25) ErythromycinMycoplasma pneumonia → indolent malaise, fever, persistent dry cough

• CXR: interstitial infiltrate • Tx: Macrolide or respiratory fluoroquinolone


26) Tetralogy of Fallot

• Most common cyanotic congenital heart condition

• Pulmonary stenosis → harsh systolic ejection murmur over left upper sternal border

• RV hypertrophy → upturning of cardiac apex → “boot-shaped” heart on CXR


27) Arthrocentesis of the knee

• Any patients with possible septic arthritis should have urgent synovial fluid analysis; septic arthritis is more likely to occur in joints that have pre-existing abnormalities (eg, osteoarthritis)

• Dx: synovial fluid analysis showing leukocytosis (>50,000), gram stain, culture


28) Culture for bacteria • Septic arthritis dx: synovial fluid analysis showing leukocytosis (>50,000), gram stain, culture


29) Potassium decreased, Bicarbonate increased • Vomiting (eg, bulimia) → metabolic alkalosis (loss of gastric HCl → ↑ HCO3−) and hypokalemia (hypovolemia → ↑ aldosterone → ↑ K+ secretion)


30) Chronic lymphocytic thyroiditis (Hashimoto disease)

• Hypothyroid features + diffuse goiter


31) Vitamin D deficiency

• Excessive alcohol consumption, previous hospitalizations for abdominal pain, and steatorrhea = pancreatic insufficiency → fat-soluble vitamin (A, D, E, K) deficiency

• ↓ vitamin D → ↓ Ca2+ and PO43− absorption from gut → symptoms of hypocalcemia


32) Pseudogout

• Pseudogout (calcium pyrophosphate dehydrate crystal deposition disease) → chonedrocalcinosis (ie calcified articular cartilage)


33) Bone marrow aspiration • Thrombocytopenia, ⊖ splenomegaly, ⊖ antiplatelet antibodies = problem with platelet production (eg, myelofibrosis)


34) Assess for suicidal ideation • Suicide risk should be assessed in patients with depression • Depression is commonly under diagnosed and underrated in cancer patients and those with terminal diseases


35) Intramuscular ceftriaxone and oral doxycycline • Outpatient antibiotic therapy for patients with PID: IM ceftriaxone + oral doxycycline or azithromycin


36) History of gastrectomy

• Gastrectomy → loss of intrinsic factor → vitamin B12 deficiency → impaired DNA synthesis