USMLE-STEP-3 Online Practice Questions and Answers

Correct Answer: C Section: (none)

Explanation:

The patient's history and examination are worrisome for pancreatic disease, and he has strong signs of pancreatic insufficiency. His long history of alcohol use suggests the possibility of chronic pancreatitis or pancreatic cancer. Fecal fat studies would only confirm or quantify his steatorrhea. ACT scan would image the pancreas for changes consistent with chronic pancreatitis (duct dilation, calcifications, pseudocysts) and could look for a neoplasm of the pancreas as well. ERCP is not indicated as a first-line test in patients with abdominal pain given its risk of causing acute pancreatitis. Upper endoscopy would be helpful to rule out peptic ulcer disease and other gastric complaints, but would not provide more global information about the abdomen. The patient has greasy stools and weight loss, findings seen in patients with steatorrhea due to chronic pancreatitis.

Patients with steatorrhea malabsorb fat-soluble vitamins (vitamins A, D, E, and K). "Night blindness" (poor night vision) due to vitamin Adeficiency is common among patients with advanced chronic pancreatitis and likely led to this patient's motor vehicle accident. The patient has DM as a consequence of pancreatic endocrine insufficiency, another feature of chronic pancreatitis. Diabetes develops when greater than 8090% of the gland has been destroyed. Patients with chronic pancreatitis have a coexisting loss of glucagon from islet cells and, thus, often become brittle diabetics, with hypoglycemia seen after insulin administration. Vitamin K and B12 deficiency, which the patient may have, do not cause hypoglycemia. The patient was previously noted to eat well, so inadequate oral intake is unlikely. Diabetic education should decrease the rate of chronic insulin overdosage.

The patient has pancreatic exocrine insufficiency and thus cannot produce enough pancreatic enzymes to digest his food. Pancreatic enzyme replacement therapy in tablet form is a mainstay of therapy for chronic pancreatitis. It can rapidly reverse this problem by providing exogenously produced pancreatic enzymes to break down fats, carbohydrates, and proteins for absorption in the small bowel. The patient would not benefit from additional oral feedings without enzyme supplementation and would only worsen his steatorrhea by doing so. He can take food orally, so feeding via gastrostomy, TPN, or PPN are not indicated. The patient's worsening pain and weight loss despite therapy is worrisome for the development of pancreatic cancer. CA-19-9 is frequently (but not universally) elevated in pancreatic cancers, although it can be elevated in cholangiocarcinoma as well. PSA is associated with prostate cancer. CEA is associated with colon cancer. CA-125 is associated with ovarian cancer. AFP is associated with hepatocellular carcinoma.

Correct Answer: C Section: (none)

Explanation:

DEXAis the newest, least expensive, and quickest method of assessing BMD. The precision of DEXAis approximately 12%. Standard radiography is inadequate for accurate bone mass assessment. Single photon absorptiometry is used to scan bone, which is in a superficial location with little adjacent soft tissue (e.g., radius). It may not be an accurate reflector of the density in the spine or hip, which are the sites of greatest potential risk for fracture. The quantitative CT scan and dual photon absorptiometry take more time, expose the patient to more radiation, and, in the case of quantitative CT scanning, significantly increase costs, when compared to DEXA. The major risk factors for osteoporosis are family history, slender body build, fair skin, early menopause, sedentary lifestyle, cigarette smoking, medications (corticosteroids or Lthyroxine), more than two drinks a day of alcohol or caffeine, and low calcium intake. The current recommendation for oral calcium in men and premenopausal women is 1000 mg/day. Postmenopausal women and patients with osteoporosis should have 1500 mg calcium a day and 400800 IU of vitamin D, which promotes intestinal calcium absorption. This patient's intake of calcium and vitamin D is not a risk factor for osteoporosis.

Alendronate is a bisphosphonate, which is approved for the prevention and treatment of postmenopausal osteoporosis. Among the many results of the WHI, it was found that combined estrogen plus progestin therapy was associated with an increased risk of nonfatal MI or death from coronary heart disease (CHD). Consequently, while it is recognized that postmenopausal women who are taking estrogen to alleviate postmenopausal symptoms may also experience skeletal benefits, the prevention of osteoporosis should not be a reason in itself to start estrogen therapy. Calcitonin inhibits osteoclastic bone resorption, but is not sufficiently potent to prevent bone loss in early postmenopausal women (within 5 years of menopause). It is best reserved for use in patients with osteoporosis unresponsive to other therapies. Raloxifene is a selective estrogen receptor modulator (SERM), which is effective for prevention of bone loss in early postmenopausal women and treatment of established osteoporosis, but it also increases the risk of venous thromboembolic disease which makes it an inappropriate choice for this patient

Correct Answer: C Section: (none)

Explanation:

Psoriasis is a benign chronic, inflammatory skin disorder with a genetic basis that affects approximately 2% of the population in the United States. The condition varies in its presentation from person to person, with some having only local involvement and others having a severe generalized involvement. The incidence occurs in a bimodal distribution, with peaks persons in their 20s and 50s. Those with earlier onset generally will have a more severe disease over the course of their lifetime. Psoriasis has several variants, or subtypes, including plaque type (most common), eruptive (guttate), generalized pustular, and erythrodermic psoriasis. Some patients may be asymptomatic or may have only minor itching. Others may have involvement of most of their body, with severe disfigurement and poor quality of life. Psoriasis may involve any skin area; however, areas such as the scalp, extensor surfaces, palms, soles, and nails should always be examined. The typical lesions are described as erythematous, well-demarcated plaques with overlying scales. Fine stippling (pitting) of the nails is highly suggestive of psoriasis. In addition to the skin findings, patients may also have arthritis. The lesions can be reactivated with local injury or irritation of normal skin (Koebner phenomenon). The diagnosis is predominantly clinical, based on the history and examination. There are no laboratory measures that will diagnose psoriasis. Skin biopsy, although not pathognomonic, would show features consistent with psoriasis and would help to rule out other similar appearing conditions.

Correct Answer: C Section: (none)

Explanation:

This patient has neutropenia (neutrophil count <500/L) with fever. For high-risk patients, such as patients with leukemia, the standard of care is to obtain cultures and a chest radiograph, perform any other studies as indicated by the patient's clinical presentation, and initiate empiric antibiotic therapy. Guidelines from the Infectious Disease Society of America recommend empiric broad-spectrum coverage for Gram-negative organisms, including anti-pseudomonal coverage. Antibiotics such as vancomycin, for Gram-positive infection, are added if there is hypotension, suspicion for a central venous catheter-related infection, or recent or current evidence for Gram-positive infection (such as MRSA colonization, or positive culture for Gram-positive cocci).

Correct Answer: B Section: (none)

Explanation:

Severe abdominal pain is the hallmark presentation of acute mesenteric ischemia. The pain is often described as being out of proportion to examination. It is most often caused by an embolic event to the SMA. Patients with cardiac arrhythmias are at greater risk for having an embolic event. Nonocclusive mesenteric ischemia is thought to be due to reactive arterial vasoconstriction and is not a surgically correctible disease. CT scan findings of SMA thrombosis or gas in the bowel wall would necessitate emergency surgery.

Correct Answer: D Section: (none)

Explanation:

The most common finding in a newborn with Down syndrome is hypotonia. Other common findings include single palmar crease, flat facial profile, macroglossia, and wide space between the first and second toes. Hypotonia in the newborn period should prompt close evaluation and follow-up. Café au lait spots are associated with neurofibromatosis. High arched palates are associated with fragile X syndrome. Ambiguous genitalia are commonly seen in CAH.

Children with Down syndrome are at an increased risk for hypothyroidism. It may be hard to detect without routine laboratory screening as they will commonly have mental retardation and developmental delay as part of their syndrome. Hypothyroidism may not be present in the immediate newborn period and requires, at a minimum, annual testing throughout the child's life. The other findings listed are not specifically associated with Down syndrome. Lens dislocation is commonly found with Marfan syndrome or homocysteinuria.

Children with Down syndrome have an increased prevalence of duodenal atresia. Pyloric stenosis is uncommon to see in the newborn period. It tends to present with nonbilious vomiting usually after 24 weeks of age. Hirschsprung disease (aganglionosis coli) presents with constipation and failure to pass stool. Infants with Hirschsprung disease commonly will not pass stool in the first days of life. Biliary atresia is a progressive cause of jaundice in an infant. It is the most common cause of a cholestatic jaundice in the newborn period. Emesis is not typically associated with biliary atresia. Milk protein allergy is a common cause of bloody stools in the first few months of life, but does not have bilious emesis associated with it.

Correct Answer: C Section: (none)

Explanation:

Pubarche in females is usually earlier than in males. Delayed puberty alone may be a pathologic condition; its presence in conjunction with short stature makes a pathologic state more likely. Males do, indeed, have adrenarche. Panhypopituitarism is a cause of puberty delay, but not a common one. Undiagnosed hypothyroidism can be a cause of pubertal delay, and thyroid function testing should be a part of the routine evaluation of this problem. The onset of puberty in males is usually signaled by an increase in testicular volume. This is commonly seen in conjunction with lengthening of the phallus and thinning of the scrotal skin. As a result of puberty, the other findings (deepening of the voice, increased muscle mass, and increased facial hair) may be seen, but the first of the listed findings to appear is increased testicular volume. In females, puberty is usually signaled by the enlargement of breast buds.

Correct Answer: C Section: (none)

Explanation:

The angiotensin-converting enzyme inhibitors (and angiotensin receptor blockers) are contraindicated in pregnancy due to their potential to cause decreased fetal renal perfusion, ultimately resulting in fetal oliguria, oligohydramnios, renal tubular dysplasia, and neonatal anuric renal failure, as well as defects in ossification of the fetal skull. These adverse effects occur during the second and third trimesters of pregnancy. If a woman conceives while taking an angiotensin-converting enzyme inhibitor, she should be changed to another agent during the first trimester.

Preeclampsia causes 5070% of cases of hypertension in pregnancy. Mild preeclampsia is characterized by an increase in systolic BP of 30 mmHg, an increase in diastolic BP of 15 mmHg, or an absolute reading of 140/90 mmHg in a pregnant patient with minimal proteinuria and pathologic edema. A systolic BP greater than 160/110 mmHg with significant proteinuria (>5000 mg/24 h) and evidence of end-organ damage indicate severe preeclampsia. End organ damage results from increased vascular reactivity, third spacing of fluids, and platelet activation. Complications include oliguria, the syndrome of hemolysis, elevated liver function tests, and low platelets (HELLP) and eclamptic seizures. Seizure prophylaxis is effective in both primary prevention of eclampsia and in prevention of recurrent seizures. Fetal macrosomia occurs more commonly in pregnancies complicated by diabetes. Abnormal labor progress and postpartum hemorrhage as well as breech presentation are not more common in pregnancies complicated by preeclampsia.

Correct Answer: A Section: (none)

Explanation:

Although antidepressant treatment may be appropriate if the patient is suffering from a depressive illness, further questioning would have to be made prior to that determination. Postpartum depressive symptoms are not uncommon and they may not require treatment. If there is felt to be immediate danger to the child, calling child protective services would certainly be indicated. Having intrusive thoughts does not equate with acting on the thoughts, and thoughts similar to those in this case are not unusual given the stress of a newborn. Again, more information would need to be obtained. On the other hand, premature reassurance regarding the thoughts of harm without knowing additional facts might be dangerous if the patient is harboring a plan or intent to harm her child. Hospitalization may be necessary if the patient is suffering from postpartum psychosis or is suicidal. Only by gathering further history and symptoms, especially focusing on a support system and possible psychotic symptoms, can the clinician determine if there is significant cause for concern. Postpartum psychosis is considered a psychiatric emergency because of the risk of harm to the infant and usually requires immediate hospitalization (DSM IV-TR).

Correct Answer: E Section: (none)

Explanation:

The presence of headache, eye pain, nausea, and vomiting should prompt the consideration of the diagnosis of acute angle closure glaucoma. This is a rare but serious condition in which the aqueous outflow is obstructed, and the intraocular pressure abruptly rises. Susceptible eyes have a narrow anterior chamber and when the pupil becomes dilated, the peripheral iris blocks the outflow via the anterior chamber angle. Edema of the cornea occurs, resulting in cloudiness on examination. Diagnosis is made by measuring the intraocular pressure during an acute attack. Treatment includes medications to induce miosis in an effort to relieve the blockage or, if that fails, surgical intervention. In some patients, the headache or GI symptoms can overshadow the ocular symptoms, resulting in a delay in diagnosis and unnecessary workup for other conditions. In this case, the lack of findings on abdominal examination makes appendicitis or perforated bowel unlikely. DKA can present with primary GI symptoms, but would not explain the ocular symptoms. Similarly, cerebellar or other brain tumors may cause headache, nausea, and vomiting, but would not be causes of a painful, red eye.