Explanations for the 2015-2016 Official Step 2 CK Practice Questions

Here are the explanations for the updated 2015 (effectively 2015-16) official “USMLE Step 2 CK Sample Test Questions,” which can be found here.

Overall, there are a solid 41 new questions when compared with last year’s set, which I’ve marked with asterisks below. For those who have done last year’s set, a list of the new question numbers is in this footnote11, 2, 5, 6, 7, 8, 13, 14, 15, 16, 17, 19, 33, 45, 47, 48, 50, 51, 52, 56, 58, 60, 61, 90, 91, 92, 95, 97, 106, 108, 111, 113, 124, 126, 130, 131, 135, 137, 138, 139, 140, and 141.. The explanations for last year’s set can still be found here.

If you’re looking for the answers to the newest June 2016 set, they’re available here. While the order is completely jumbled, there are only two new questions.

Block 1

1. A – This patient has urge incontinence, which is commonly caused by detrusor instability (and can be treated with anticholinergics like oxybutynin). This is opposed to stress incontinence, the other most common type, which is worsened by abdominal pressure/coughing/laughing/etc and can be caused by pelvic floor prolapse secondary to multiple childbirths etc. Neurogenic bladder can cause overflow incontinence.*
2. B – Catecholamines, such as those released by a functioning pheochromocytoma, are made by the chromaffin cells of the adrenal medulla. Episodic headache/hypertension is the tip-off here.*
3. A – Dermatomal rash means zoster. Immune insults, like chemotherapy, predispose to zoster flares.
4. C – Remember cystic fibrosis in young people with worsening obstructive lung disease and frequent infections. The infertility in males is secondary to failure of the vas deferens to develop properly (in women, it’s due to thick cervical mucus). Sweat chloride test makes the diagnosis.
5. D – Walking pneumonia is treated with macrolide antibiotics as first line. Patchy infiltrates in a patient with clinical pneumonia symptoms who otherwise young, healthy, and walking around…think mycoplasma.*
6. B – Alcohol raises GGT. The other liver enzyme lab to remember is the 2:1 or greater AST/ALT ratio associated with alcoholic liver disease.*
7. D – The inclusion bodies signify that this patient has a CMV infection of the renal transplant, which can originate from either the donor or recipient but are activated/unmasked by immune suppression. CMV is an important cause of morbidity and mortality in renal transplants and both the donor/recipient are routinely screened.*
8. C – Neutropenic fever requires IV antibiotic therapy, which should include an agent with anti-pseudomonas activity (such as the third-gen cephalosporin ceftazadime, the fourth gen cefepime, or piperacillin/tazobactam)*
9. F – TTP always seems like too many disparate symptoms but just remember the pentad: thrombocytopenia, microangiopathic hemolytic anemia, neurologic symptoms, renal failure, and fever.
10. G – Pleuritic chest pain and hypoxia with a normal chest x-ray should lead you to pulmonary embolism. There’s usually enough total lung and blood flow, but it’s the mismatch that’s the issue.
11. F – Weight loss and worsening lung symptoms in a smoker means lung cancer. Non-small cell is by far the most common variety.
12. E – The large cystic midline pelvic mass is her bladder, which is full of urine and must be decompressed emergently before any further workup is pursued.
13. A – Proximal muscle weakness + skin findings = dermatomyositis. Yes, kids can get this. In this case, they’ve gone to the trouble of describing Gottron’s papules (“flat-topped red papules over all knuckles”) and the heliotrope rash (purple-red discoloration over the eyelids).*
14. D – Painless uterine bleeding goes with placenta previa. Painful uterine bleeding goes with placental abruption. Ruptured vasa previa results in rapid loss of the fetus.
15. E – Clavicle fractures are a common birth trauma of no long-term clinical significance.*
16. B – Wide split fixed S2 is an ASD.*
17. F – Septic arthritis (rapidly warm swollen joint +/- fever) must be tapped, followed by antibiotics. Untreated, the joint can be destroyed in days. Minor trauma can predispose to hematogenous bacterial spread.*
18. D – Pain and swelling behind the ear means mastoiditis (remember the mastoid air cells?). The cause is nearly universally direct spread from otitis media.
19. A –Via urinalysis and renal ultrasound, we’ve excluded serious/treatable causes of renal hypertension including Conn’s disease (hyperaldosteronism) and renal artery stenosis such as due to fibromuscular dysplasia. That leaves her obesity.*
20. D – Euvolemic hyponatremia means SIADH. Both brain and lung insults are common causes. Nonphysiologic secretion is “inappropriate,” of course.
21. E – LLQ pain with fever equals diverticulitis. The test of the choice is a CT scan of the abdomen with contrast.
22. D – Transillumination of a scrotal mass equals a hydrocele, which is due to a patent processus vaginalis.
23. B – Irregular heavy menstrual bleeding in otherwise young healthy women is almost always due to anovulatory cycles. A normal pelvic ultrasound essentially rules out the rest.
24. A – Low pH means acidemia. Renal failure causes metabolic acidosis (hence low bicarb). Low CO2 is the respiratory compensation. If it was vice versa, the pH would be high (alkalemia).
25. B – Folic acid prevents neural tube defects. End stop.
26. C – Follow your ABCs. Tachycardia and hypotension mean severe volume loss necessitating aggressive intravenous fluid resuscitation.
27. A – Nighttime cough and hoarseness imply laryngopharyngeal reflux (GERD that spills over into the larynx). In real life, you might try a PPI trial, but pH monitoring will confirm the diagnosis.
28. B – Endometriosis is a common cause of infertility and is associated with chronic pelvic/abdominal pain and excruciating periods. The gold standard for diagnosis is laparoscopy (visualization of “chocolate cysts”).
29. B – A p-value less than 0.05 means that the results are statistically significant. However, most would agree that roughly 7 hours difference in cold duration is clinically insignificant.
30. E – Don’t let the carpal tunnel history fool you. Numbness of the pinkie and half of the ring finger is ulnar entrapment (which happens at the elbow); carpal tunnel syndrome is the median nerve at the wrist (affecting thumb, index, middle, and half of the ring)
31. D – Atopic dermatitis (eczema) is the “itch that rashes.” It’s one leg of the allergic triad: asthma, allergic rhinitis, and atopic dermatitis. Treatment is with topical steroids and rigorous emollient therapy.
32. A – Autonomy matters. If a patient has the capacity to make medical decisions (i.e. understands the risks) and is not an imminent harm to self or others (i.e. suicidal or homicidal), then he cannot be held against his will. We don’t institutionalize people just for noncompliance with medical treatment.
33. D – First-line treatment for panic disorder (and all anxiety disorders) is SSRI therapy. The only time you answer “benzodiazepine” (which wasn’t offered as a choice, because it would be arguable) for a panic disorder question is when they ask you what drug is “most likely to treat the episode” or something along those lines. BZDs work immediately; SSRIs take time.*
34. B – Type II error is the possibility of producing a false negative (a negative result when it should be positive). A smaller sample size may not be able to detect a small (but real) treatment effect and thus increases the chance of type II error.
35. B – Altered consciousness (intoxication, seizure, etc) predisposes to aspiration. Aspiration PNA typically goes to the RLL when upright and RUL when supine, and the damage is done by nasty GI anaerobes.
36. B – Myocardial infarction causes heart muscle death (as the name implies). Lose enough muscle and you get systolic heart failure.
37. B – One of the S in SIGECAPS is for suicidality. Depression is extremely common, and it’s also underdiagnosed in cancer patients.
38. E – Abnormal vaginal bleeding in a woman over 35 requires an endometrial biopsy to rule out endometrial cancer.
39. B – Marfan syndrome (you know, hinted at by the familial tall stature and weak hypermobile joints) is associated with a dilated/aneurysmal aortic root, which can worsen, dissect and/or rupture if not monitored.
40. D – You know what causes sudden onset headache and neck stiffness? Subarachnoid hemorrhage. The first episode can be transient, the so-called sentinel bleed before a catastrophic aneurysmal bleed.
41. A – Most common palpable breast mass in women less than 30 is fibroadenoma. In women between 30-50, it’s a cyst (or fibrocystic changes of the breast). Greater than 50, malignancy.
42. E – Everyone should get a flu vaccine. Diabetics are relatively immune suppressed and deserve it even more.
43. B – Asymptomatic bacteriuria is never treated, except in pregnancy, when it should always be treated due to its association with preterm labor. Treat with an oral antibiotic that covers gram negatives (like E coli), such as amoxicillin or nitrofurantoin.
44. B – Diabetes get diabetic nephropathy. Don’t over-think things.

Block 2

45. C – We can only put the laboratory tests into context if we have an accurate gestational age. Since her LMP is unreliable (totally unknown), we need an ultrasound to date her pregnancy.*
46. E – Crescents mean rapidly progressive glomerulonephritis (RPGN—bad news bears). Immune complexes along the basement membrane mean Type II, such as seen with lupus, IgA nephropathy, acute proliferative glomerulonephritis, and Henoch-Schönlein purpura. Treated with immune suppression, which in the acute phase always means steroids.
47. B – The STD that forms a painful ulcer aka chancroid = H ducreyi (ducreyi makes you cry, as they say).*
48. B – Repetitive vomiting (be it due to viral gastroenteritis or bulimia) leads to hypokalemic hypochloremic metabolic alkalosis. Alkalosis means elevated bicarbonate, which in this case is created as the byproduct of increased stomach acid production.*
49. D – Mitral valve stenosis is a sequela of rheumatic heart disease that can lead to LAE and left-sided heart failure if left untreated.
50. A – These questions can be a true pain of biochemistry on the Step 1 or relatively straightforward depending on how well you know it. This patient has classical Galactosemia, caused by a deficiency in galactose-1-P uridyl transferase deficiency, the enzyme that converts galactose and lactose to glucose. Intolerance to dairy, hepatomegaly/liver disease/jaundice with hypoglycemia due to decreased gluconeogenesis, and reducing substances in urine are classic. Listlessness and lethargy ensue with mental retardation and eventually death if untreated. Cataracts are also common. If you didn’t get to galactosemia (or thought it was Von Gierke’s disease, which isn’t all that unreasonable), the answer is still A. By process of elimination, given the serum hypoglycemia but no urine glucose, the issue is an inability to make glucose from stores (not to absorb it).*
51. D – Pinpoint pupils are a classic tip off for opioid use (caused by parasympathetic activation). Barbiturate toxicity is associated with nystagmus but not necessarily pupil size changes. Neither alcohol nor barbiturates would be likely choices in this context because they have similar effects (along with benzodiazepines).*
52. B – They describe claudication and vascular insufficiency with strong flow in the groin and no palpable flow distally in the dorsalis pedis, placing the level of stenosis somewhere in between (i.e. femoropopliteal). Diabetes and smoking are two big risk factors for peripheral arterial disease (PAD).*
53. E – Intermittent polyarthritis with positive ANA (sensitive but not specific) and anti-DNA (very specific) means lupus. You don’t even need the nonpainful mouth ulcers.
54. A – Frequent turning prevents the development of pressure ulcers in patients with decreased mobility.
55. B – This patient has chronic (6 weeks) symptomatic hypotension while not coincidentally on three BP meds: a diuretic, a beta blocker, and an ACE inhibitor. The most likely explanation and easiest/fastest intervention is to reduce her polypharmacy.
56. C – Multinodular goiter! Say it five times fast. Feels good, doesn’t it? The first half describes blatant hyperthyroidism. The thyroid scan is now demonstrating an enlarged gland with multiple nodules (“areas”), some avid/hyperfunctioning and other relatively depressed (either not “hyper”-functioning and thus relatively cold or actually cold, most commonly filled with colloid).*
57. A – Even if you forget the signs/symptoms of Kawasaki’s disease, which you shouldn’t (strawberry tongue is a giveaway), just remember it’s essentially the diagnosis for any child with 5 days or more of fever. Treatment is aspirin (the one time it’s okay in children) and IVIG.
58. G – MS is characterized by neurologic deficits separated in time and space, often but not always transient. She has an isolated episode of optic neuritis (a common initial attack).  The normal CK is given to help you exclude a primary muscle process.*
59. D – Abdominal pain is a common presenting complaint of DKA, which is a common presentation of new-onset type 1 diabetes. Note the glucose of 360.
60. A – Breath-hold spells are not an uncommon tantrum maneuver for young children. Don’t let a few jerks convince you this is a seizure; a little bit of syncopal myoclonus is extremely common. This is why all of those patients come to ER for “seizures” when they really syncopized because some bystander saw them jerking around a bit.*
61. D – The description of a primary lung cancer with associated muscle weakness is leading you to Lambert-Eaton myasthenic syndrome, a paraneoplastic autoimmune condition where antibodies attack the presynaptic calcium channels of the neuromuscular junction. Lung-cancer paraneoplasias are test favorites.*
62. H – Recurrent infection and abscesses should raise the suspicion of chronic granulomatous disease. Suppurative arthritis does even more, if you’re likely to remember that. The real diagnosis is made from the Step 1 style question. Nitroblue tetrazolium is the test used to diagnose CGD, which is a defect in NADPH oxidase (the oxidative burst that kills Staph aureus).
63. C – Weight loss and iron deficiency anemia are concerning for colon cancer with occult blood loss. Colonoscopy is required. Parasitic causes of iron deficiency (e.g. hookworm) are first tested with stool ova & parasite screening.
64. E – Bronze diabetes and arthritis means hemochromatosis. They never say the words “bronze diabetes” on board questions, but it doesn’t mean it’s not there.
65. C – Macrocytic anemia with sensory changes is indicative of B12 deficiency. Causes include the classic pernicious anemia, but don’t forget the complications of GI surgery. Intrinsic factor is made by the stomach’s parietal cells.
66. F – Vasculitides like Wegener’s granulomatosis, microscopic polyangiitis, and others causes poly-symptom disease and glomerulonephritis (hence the hematuria and proteinuria). Positive ANCA, (either P-ANCA or C-ANCA depending on the variant) is the key laboratory finding.
67. E – An acutely swollen painful great toe means gout. Gout is an inflammatory crystalline arthropathy. Aspiration reveals white cells and negatively-birefringent needle-shaped crystals.
68. A – RUQ pain and nausea after meals equals symptomatic cholelithiasis. The test of choice is RUQ sono to assess for stones.
69. C – Obstructive sleep apnea (OSA) is diagnosed exclusively by polysomnography (aka a sleep study).
70. B – Two things make this aortic dissection instead of a heart attack or pulmonary embolism. First, the diastolic murmur is that of aortic insufficiency/regurgitation, which is happening because the dissection is involving the aortic root. Second, the presence of diminished femoral pulses implies that the dissection also involves the descending thoracic aorta distal to the takeoff of the brachiocephalic and left subclavian arteries (which supply the arms). Only an issue in the aorta can cause that constellation of symptoms.
71. E – ABCs. Patient has an airway (evidenced by breath sounds without mention of other complicating factors like unconsciousness). Move on to B. Asymmetry implies a hemo-, pneumo-, or hemopneumothorax, which requires a chest tube immediately.
72. D – The radiograph is showing complete collapse of the left lung (2/2 mucous plugging) with resultant severe mediastinal shift. Acute shift can have the same effect as any other “tension”-type process, causing impaired venous return to the heart and decreased cardiac output via the Starling mechanism.
73. C – Meningitis/encephalitis symptoms (fever, headache, altered mental status) with monocytic predominance and only mildly elevated protein on CSF studies go along with viral meningitis, such as HSV.
74. E – Thrombocytopenia without antiplatelet antibodies or splenomegaly implies a platelet production problem (e.g. myelofibrosis). History of radiation therapy is a risk factor. The only way to know what’s happening at the factory is a bone marrow biopsy.
75. F – SIGECAPS+. Patient has MDD and developing panic disorder. Both of these can be treated first-line with SSRI therapy, such as paroxetine (Paxil).
76. E – Exfoliative and blistering drug reactions come in three severities of the same mechanism: erythema multiforme, Stevens-Johnson syndrome, and toxic epidermal necrolysis. Diffuse involvement (>30%) is consistent with toxic epidermal necrolysis (TEN), which carries a 30-40% mortality.
77. D – Fever, AMS, and muscle rigidity in a patient on antipsychotics (aka ‘neuroleptics’) means neuroleptic malignant syndrome (NMS). Very rare, very dangerous.
78. A – Cough is often the only sign of asthma. Exercise-induced asthma is exercise-induced asthma.
79. A – Patients who suffer blunt abdominal trauma get CT scans when stable. Contrast is needed to assess for solid organ injury (e.g. kidneys).
80. A – It’s not clear that the glucose is a fasting value or not, but it’s clear that the patient has symptoms of diabetes in the context insulin resistance (obese kid with acanthosis nigricans). Diet and exercise are always necessary in DM2 and can reverse many early cases. With a 10% weight loss, for example, the patient may not require pharmacotherapy.
81. A – Organ donation is a complex organizational dance, and the regional procurement organization manages the nitty-gritty aspects.
82. B – The first imaging test for acute stroke is a noncontrast CT scan of the head. At 12 hours out, it may show ischemic strokes, but more importantly, it will diagnose hemorrhagic strokes, for which antiplatelet therapy is contraindicated.
83. A – Lisinopril and especially spironolactone (a K-sparing diuretic) can both cause hyperkalemia. Renal failure (severe AKI or ESRD) is also a major cause of hyperkalemia, but not by itself with the only mildly elevated Cr and BUN levels.
84. C – Polycystic ovarian syndrome (PCOS) is treated with estrogen-containing birth control (OCPs). Metformin would be an additional appropriate pharmacotherapy.
85. A – Lyme disease (from tick bites while hiking) can cause Bell’s palsy.
86. C – Anesthesia to the anterolateral thigh is the distribution of the lateral femoral cutaneous nerve. LFC neuropathy can be caused by compression near the inguinal ligament (say, from a hematoma). Note that it’s the compression of the nerve that causes decreased sensation, not the hematoma itself.

Block 3

87. D – Fever and lower abdominal pain during pregnancy equals endometritis. Infection is a major cause of PROM.
88. D – Bartholin’s cysts get incised and drained. When recurrent, they can be marsupialized, which isn’t as fun as it sounds.
89. D – They hit you over the head with hypocalcemia symptoms before giving the value. Hidden in there is the pancreatic insufficiency causing steatorrhea and fat-soluble vitamin deficiency (A, D, E, and K).
90. C – Again, acute RUQ pain (especially in an obese woman) should set off the gallstone alarms. Fever and other systemic signs, white count, etc lead you down the acute cholecystitis. Simple pain leads you to symptomatic cholelithiasis. Either way, the first step is to get a RUQ sono to see those stones!*
91. B – Posttraumatic AV fistula! Just like dialysis AV fistulae have bruits and thrills, so do non-purposeful created ones. These can take a long time to form but can be associated with steal syndromes due to decreased perfusion to the distal extremity, venous incompetence, varicosities, and eventually stenoses due to unreasonably high flow, and even high-output heart failure.*
92. D – Meniere disease is characterized by recurrent vertigo attacks associated with ear fullness, tinnitus, and hearing loss.*
93. A – PTSD symptoms that begin within 4 weeks of a traumatic event and last 4 weeks or less is acute stress disorder (ASD).
94. D – A boot-shaped heart means Tetrology of Fallow on board exams. Outside of that giveaway, TOF is by far the most common cause of cyanotic heart disease.
95. C – Interstitial nephropathy (also known as tubulointerstitial nephritis) is most commonly an allergic-type reaction to medications, typified by eosinophils in the urine. The nonspecific maculopapular reaction is also the common type of drug reaction rash and is seen in a minority of cases, as is low-grade fever (not critical to the question). Several medications can cause this, penicillins, cephalexin, and NSAIDs are the most common.*
96. E – Weight gain, fatigue, and constipation go with hypothyroidism. High LDL cholesterol actually does too, but the question is doable even when ignoring the lab values.
97. D – The patient has a small bowel obstruction, likely due to adhesions from prior surgery, evident clinically and confirmed by radiograph (dilated small bowel without distal colonic dilation to suggest paralytic ileus). Conservative treatment in a stable patient involves NG tube decompression and NPO. A CT can be obtained for further characterization (and would be in real life), but there is no reason to delay appropriate care to get it.*
98. F – Premature babies get neonatal respiratory distress syndrome due to surfactant deficiency.
99. B – Multiple lytic bony lesions equals multiple myeloma. Blastic/sclerotic lesions should make you think of metastatic prostate cancer (in men) and breast cancer (in women).
100. D – Super contagious super itchy rash of the hands and fingers (especially the webs!) is scabies. Viral exanthems do not localize to the waistband and hands.
101. E – Pseudogout (calcium pyrophosphate deposition disease) is an inflammatory arthritis with a predilection for the knee that causes synovial calcifications.
102. E – The only thing you do with things that look like primary melanoma is excise them completely.
103. A – They’ve listed the criteria for ADHD. Note that conduct disorder is the kid-version of antisocial behavior. If the kid breaks rules and messes up but doesn’t seem evil, then it’s not conduct disorder.
104. E – Of the choices listed, only X-linked agammaglobulinemia causes recurrent respiratory bacterial infections. CGD results in multiple abscess-forming infections (predominately Staph aureus). B and C also cause recurrent viral infections in addition to bacterial disease.
105. B – Confusion and tremulousness a few days after an unexpected hospital admission on the USMLE means alcohol withdrawal (unanticipated detox).
106. E – You know this patient has hemolytic anemia secondary to an RBC fragility issue: hemolysis of fragile RBCs is leading to indirect (unconjugated) hyperbilirubinemia and jaundice. In spherocytosis, these are destroyed in the spleen causing splenomegaly (and consequently splenectomy is also a treatment). The genetics finish the job here: the disease is present in multiple individuals (including her mother) on one side of her family, as HS is AD disease. Sickle cell, by comparison, is AR, has more symptoms, and while splenectomy would be common, would not lead to a resolution of symptoms.*
107. A – It’s a cholesteatoma, which can be congenital or acquired. Even if you have no idea what that is (look it up), it’s the only answer with “proliferation” to go along with the mass. None of the others mention anything remotely mass-like.
108. B – The drugs of choice for Alzheimer’s-type dementia (i.e. general dementia without specific factors to make you consider other diagnoses) are the cholinesterase inhibitors, the most important of which is Donepezil.*
109. B – Thick, white, and acidic means candidal vulvovaginitis (aka a yeast infection). Bacterial vaginosis typically only causes foul odor (and is alkaline, has a positive whiff test, clue cells on wet mount, etc).
110. D – If environmental, food, or exposure allergies ever include shortness of breath, then carry an epi-pen.
111. D – Consider bacterial sinusitis to be analogous to bacterial pneumonia. All are possible, but Strep pneumo is the most common.*
112. A – Headache and stiff neck clues you to meningitis. In a college student, that’s enough for the diagnosis. Stop reading. The treatment is ceftriaxone.
113. E – Thiazides have an interesting effect: they decrease urinary excretion of calcium. This can be used therapeutically, in addition to their diuretic effect, as both as preventative treatment of hypercalciuria / calcium stones as well as a treatment for hypocalcemia.*
114. A – Totally healthy people with indirect hyperbilirubinemia means Gilbert syndrome (which causes decreased bilirubin conjugation due to reduced glucuronyltransferase activity).
115. D – The majority of twins are born premature, which is even more true for triplets. Only monochorionic twins experience twin-twin transfusion syndrome (as they have to share a blood supply in order for the problem to occur).
116. B – Lumbar strain doesn’t require specific treatment or workup.
117. E – Working up serious hypoglycemia involves measurement of both insulin and C-peptide (the cleaved by-product of endogenous proinsulin) to assess for hyperinsulinemia and distinguish endogenous (e.g. insulinoma) from exogenous (e.g. Munchausen’s) causes.
118. C – Patients who have the capacity to make medical decisions are allowed to refuse life-saving medical treatment. You should offer it but accept her refusal.
119. A – The differential for chronic diarrhea in an AIDS patient includes bacterial, viral, and parasitic causes as well as HIV enteropathy. Cryptosporidium is a protozoa that classically causes watery diarrhea in AIDS patients, especially those exposed to unclean water sources (hence the traveling to Asia). CMV is a reactivation infection and MAC is ubiquitous; disease caused by either of these pathogens is due to severely depressed immunity (i.e. CD4 < 50).
120. D – STDs are always double-treated for both chlamydia and gonorrhea, as coinfection is extremely common, and clearance is crucial to prevent reinfection and continued spread. That means anyone with cervicitis or urethritis gets azithromycin or doxycycline with ceftriaxone.
121. A – Repetitious vomiting leads to the classic hypokalemic hypochloremic metabolic alkalosis, as well as run of the mill dehydration (hyponatremic hypovolemia). So—low sodium, low potassium, low chloride, high bicarbonate.
122. D – Unstable and hypotensive patients after blunt trauma get laparotomies (don’t put an unstable patient in the CT scanner). In addition to saline and blood products, it’s how you address the C in ABC.
123. E – Genital warts don’t hurt and they turn white with vinegar (acetic acid). No systemic therapy works (although there is now a vaccine), but cryotherapy (as well as laser and electrocautery) can help. HPV will remain, however, and the lesions can recur.

Block 4

124. A – Heavy alcohol consumption causes hypercholesterolemia and particularly hypertriglyceridemia, as well as liver damage and dilated cardiomyopathy.*
125. A – Repeated microtrauma from repetitive stress can cause thrombosis. DVT leads to erythema and venous engorgement, the other choices do not. For bonus points, the eponym for effort-induced upper extremity DVT is “Paget–Schroetter disease” (for those keeping track at home).
126. E – Healthy children require only symptomatic treatment of the disease and no exposure-related prophylaxis. Varicella immunoglobulin (choice B) is used for prophylaxis in immunocompromised/immunosupressed persons; acyclovir (kinda choice A) is used to treat adults and immunocompromised persons who have varicella due to its frequently more complicated course than that seen in healthy children.*
127. D – The lungs are clear. Location, JVD, and lack of heart sounds mean cardiac tamponade from hemorrhage into the pericardium. Pericardiocentesis is the next step. Don’t forget, if you see tension pneumothorax or a water-bottle heart (from tamponade) on chest x-ray, you’ve already delayed life-saving therapy.
128. D – Microcytic anemia is essentially always iron-deficiency unless there is a reason to suspect a thalassemia. In this case, extensive surgery has removed nutrient absorbing small bowel.
129. B – The patient has rhabdomyolysis from a prolonged visit with the floor. The ridiculously high CK confirms the diagnosis. Rhabo causes renal failure and requires aggressive fluid resuscitation.
130. B – Remember: diverticulosis bleeds, diverticulitis hurts. Tics are increasingly common with age and are the most common cause of large volume BRBPR (some would argue angiodysplasia is actually more common, but nonetheless tics are more commonly blamed). Colon cancer causes small volume occult bleeding, particularly when right-sided, resulting in iron deficiency anemia. Hemorrhoids don’t pour out resulting in a hemodynamic instability (think blood on the TP when wiping). IBD also likewise doesn’t result in spontaneous massive painless lower GI bleed. A duodenal ulcer (an upper GI source) will generally show up on NG-aspiration and is more commonly associated with hematemesis and melena. This question will show up your exam, and while very easy, illustrates important concepts on differentiating GI bleeds, which is high yield.*
131. B – The primary mechanism by which beta-blockers reduce angina is via decreased contractility, which reduces the oxygen demand of the myocardium (which has a constrained supply due to coronary artery disease). Lowering heart rate also helps, but that isn’t one of your choices.*
132. A – Sudden respiratory failure after rupture of membranes means amniotic fluid embolism (it’s not like a fat embolism; it’s actually an allergic reaction). Can happen during labor or secondary to trauma. Hypotension and coagulopathy ensue.
133. E – Bilateral hilar adenopathy nearly always means sarcoidosis on board exams, especially in women in their 30-40s (and even more so if African-American). It’s a multisystem disease that can affect anything.
134. A – The most common cause of hypothyroidism in developed countries is Hashimoto’s thyroiditis. In developing countries, it’s iodine deficiency.
135. D – A nagging persistent dry cough is a common side effect of ACE-inhibitors due to bradykinin accumulation (bradykinin is normally degraded by ACE). Along with angioedema, it’s an important reason for discontinuation; the solution for both is to switch to an angiotensin II-receptor blocker (ARB) like losartan, which does not affect ACE activity directly.*
136. C – Bipolar disorder is the only reasonable answer, as evidenced by the increased energy, elevated mood, labile affect, and poor judgment and focus. You don’t develop ADHD at 32.
137. E – Volume depletion is far and away the most common cause of AKI, and is clinically evident here by the history of intractable vomiting and presence of dry mucous membranes. The lack of blood and white cells in the urine leads you away from the various inflammatory causes. There is no mention of the muddy brown casts associated with ATN, and the low urine sodium 2Urine Na varies depending on intake, but consider 20 mEq/L to be an average “normal” demonstrates a preserved ability to concentrate and preserve water/sodium as a response to dehydration; this is the opposite of what happens in ATN, where damage to the renal tubules prevents the absorption of sodium, resulting in a fractional excretion greater than 3%.*
138. A – The whole method of the “sweat test” is that persons with CF have salty sweat. Therefore, in settings where they sweat profusely, they lose more electrolytes than the average person and are thus more susceptible to dehydration.*
139. C – The child has a history of bacterial (B-cell) and fungal (T-cell) infections, hence he has SCID, the “combined” immunodeficiency. While DiGeorge syndrome (thymic aplasia) results in severe T-cell deficiency, and helper T-cells are important activators of B-cells, it is less likely than SCID to have such depressed immunoglobulin levels. Also, DiGeorge  syndrome has a variety of associated nonimmunologic features which would typically be mentioned in questions.*
140. A – An egg allergy is the most common contraindication to receiving the flu vaccine.*
141. D – You want to say smoking, but it’s not an answer choice. Weight loss is the next best answer. The correlation between caffeine, stress and blood pressure is not as strong.*

Corrections, clarifications, copy/paste errors etc can be made/asked/mocked in the comments below.