Uworld37

Question 1

Renal papillary necrosis classically present with

Answer 1

gross hematuria, acute flank pain, and passage of tissue fragments in urine.

It is most commonly seen in patients with sickle cell disease or trait, diabetes mellitus, analgesic nephropathy, or severe obstructive pyelonephritis

Question 2

Hereditary spherocytosis results from?

Answer 2

red blood cell cytoskeleton abnormalities, most commonly in the proteins spectrin and ankyrin.

The diagnosis can be confirmed with a positive osmotic fragility test. Hemolytic anemia, jaundice, and splenomegaly are classic manifestations.

Complications include pigmented gallstones and aplastic crises

Question 3

formula of specificity

Answer 3

the specificity of a test is its ability to correctly identify individuals without the disease

Specificity = true negatives / (true negatives + false positives)

Question 4

mechanism of shiga toxin

Answer 4

Shiga toxin is produced by enterohemorrhagic escherichia coli and shigella dysenteriae.

It inhibits the 60S ribosomal subunit in human cells, blocking protein synthesis and causing cell death

Question 5

how does combination oral contracetive pills treat hirsutism?

Answer 5

male pattern hair growth in women is called hirsutism; the most common cause is polycystic ovary syndrome.

Combination oral contraceptive pills can treat hirsutism by suppressing pituitary LH secretion and subsequently decreasing ovarian androgen production.

Question 6

treatment of gonococcal urethritis +/- chlamydia

Answer 6

urethritis in young men is usually due to sexually transmitted infection.

Treatment for gonococcal urethritis with uncertain or positive chlamydia coinfection status is ceftriaxone plus doxycycline.

Treatment for gonococcal urethritis with negative chlamydia is ceftriaxone alone.

Patients with no gonorrhea who have chlamydia are treated with azithromycin or doxycycline monotherapy

Question 7

schistocytes are seen in which diseases

Answer 7

schistocytes suggest microangiopathic hemolytic anemia (hemolytic uremic syndrome, thrombotic thrombocytopenic purpura, disseminated intravascular coagulation or mechanical damage (prosthetic valve)

In childhood, HUS is often preceded by bloody diarrhea. Coagulation studies (prothrombin time and partial thromboplastin time) are normal in HUS-TTP but abnormal in DIC.

Question 8

what is Zika virus

Answer 8

a single stranded RNA virus that infects fetal neural progenitor cells, causing severe congenital malformations (microcephaly, arthrogryposis), cerebral cortical thinning, and possible fetal demise

Question 9

what is a leukemoid reaction

Answer 9

a significant leukocytosis (may exceed 50,000) that occurs in response to an underlying condition, commonly severe infection.

Blood smear often shows neutrophilia with reactive features (Dohle bodies), as well as increased neutrophil precursors (bands, metamyelocytes, myelocytes).

The leukocyte alkaline phosphatase score is normal or increased.

Question 10

What is the triad of Wernicke syndrome?

Answer 10

oculomotor dysfunction, ataxia, and confusion form the triad of Wernicke syndrome.

Most of these symptoms usually resolve after thiamine administration.

Korsakoff syndrome is a chronic and irreverisble complication of Wernicke encephalopathy, the hallmarks of which are permanent memory loss and confabulation.

Question 11

What is the most common complication of aneurysmal subarachnoid hemorrhage?

Answer 11

vasospasm, which typically occurs 3-12 days after the initial insult and can cause delayed cerebral ischemia (sudden change in mental status, new focal neurological deficits).

The CT scan usually remains unchanged, unlike with rebleeding.

Question 12

What is the most abundant amino acid in collagen?

Answer 12

Glycine.

The triple helical conformation of collagen molecules occurs due to the repetitive amino acid sequence within each alpha chain, in which glycine (Gly) occupies every third amino acid position (Gly-X-Y)

Question 13

What is a schwannomas?

Answer 13

present histologically with a biphasic pattern of cellularity (antoni A and B areas) and S-100 positivity (indicating neural crest origin).

Schwannomas can arise from the peripheral nerve, nerve roots, and cranial nerves (except CN II and CN I).

Acoustic neuromas are the most common type of intracranial schwannoma and are located at the cerebellopontine angle at CN VIII.

Question 14

MOA of methadone

Answer 14

slows the delayed rectifier potassium current responsible for ventricular repolarization, and high doses are associated with QT interval prolongation.

QT interval prolongation predisposes to the development of torsade de pointes, a serious ventricular arrhythmia that can cause syncope and sudden cardiac death

Question 15

Organ susceptibility to infarction after occulusion of a feeding artery is ranked from greatest to least as follow:

Answer 15

central nervous system, myocardium, kidney, spleen, liver

The presence of a dual and/or collateral blood supply (as seen in the liver, which is supplied by the hepatic artery and portal vein) enables an organ to tolerate arterial occlusion better than those with end-arterial circulations.

Question 16

what is takaysu arteritis?

Answer 16

chronic, large artery vasculitis that primarily involves the aorta and its branches.

It presents with constitutional (fever, weight loss) and arterio-occlusive (claudication, blood pressure discrepancies, pulse deficits) findings in patients age <40

Histopath shows granulomatous inflammation of the vascular media

Question 17

the onset of action of a gas anesthetic depends on

Answer 17

its solubility in the blood (blood/gas partition coefficient)

Drugs with high blood/gas partition coefficients are more soluble in the blood, demonstrate slower equilibrium with the brain, and have longer onset times

Question 18

osteonecrosis (avascular necrosis) occurs due to?

Answer 18

disruption of the macrovasculature or microvasculature of bone.

The femoral head is the most common location.

Sickle cell disease can cause osteonecrosis due to the thrombotic occlusion of arteries.

Other major risk factors include embolic disorders, high dose systemic corticosteroids, excessive alcohol use, vasculitis (eg, systemic lupus erythematosus) and femoral neck fracture

Question 19

what are the most common masses in the anterior mediastinum?

Answer 19

thymoma, teratoma (and other germ cell tumors), lymphoma and thyroid neoplasm.

An anterior mediastinal mass with elevated serum levels of alpha fetoprotein and beta-hCG is classic for nonseminomatous germ cell tumor

Question 20

moa of azathioprine

Answer 20

an immunosuppression drug that is metabolized into active metabolites by hypoxanthine-guanine phosphoribosyltransferase and inactivated by xanthine oxidase.

Coadminstration with a xanthine oxidase inhibitor (allopurinol, febuxostat) shunts azathioprine metabolism toward the production of active metabolites, resulting in increased immunosuppression and risk of cellular toxicity

Question 21

what is creatinine

Answer 21

creatinine, a waste produce generated by the breakdown of creatine in the muscles, is used to estimate the glomerular filtration rate.

Creatinine formation is dependent on muscle mass and meat intake; therefore, patients with low muscle mass (elderly patient, those with amputations) or low intake (low protein vegetarian diet) can have significantly lower GFRs for any given creatinine level

Question 22

translocation for acute promyelocytic leukemia

Answer 22

the cytogenic defect t(15;17) is associated with acute promyelocytic leukemia (AMPL).

A translocation involving the retinoic acid receptor alpha (RARA) gene from chromosome 17 and the promyelocytic leukemia (PML) gene on chromosome 15 leads to the formation of PML/RARA, a fusion gene whose product inhibits differentiation of myeloblasts and triggers the development of APML

Question 23

what is schistosomiasis

Answer 23

a parasitic blood fluke infection that is associated with bathing in freshwater contaminated with cercariae from infected snails.

Patients often are asymptomatic for months or years but may eventually develop eosinophilic granulomatous inflammation in the liver, spleen, gastrointestinal tract, or genitourinary system.

One common manifestation of genitourinary schistosomiasis is painless terminal hematuria, eggs can often be identified in the urine or on biopsy

Question 24

What is disseminated intravascular coagulation

Answer 24

a common complication of gram negative bacterial sepsis due to activation of the coagulation cascade by bacterial endotoxins, which leads to the formation of micro thrombi.

Peripheral smear shows fragmented erythrocytes (schistocytes) and thrombocytopenia.

Labs: decreased fibrinogen and prolonged PT and PTT

Question 25

what is molluscum contagiosum

Answer 25

caused by poxvirus and presents with small, firm, rounded papules that often have a central umbilication.

Adults who are immunocompromised (HIV) or sexually active are at increased risk

biopsy: intracytoplasmic eosinophilic inclusion bodies of poxvirus in ketatinocytes

Question 26

what is tuberous sclerosis complex

Answer 26

AD disorder characterized by benign hamartomas of the brain (ie, cortical glioneuronal hamartomas and subependymal nodules) and skin

Seizures and ash leaf spots are common presenting signs

Question 27

what are the major defects in tetralogy of fallot

Answer 27

right ventricular outflow tract obstruction and ventricular septal defect.

In many patients, activities (feeding, crying) can precipitate cyanotic episodes (tet episodes) by causing a dynamic increase in RVOT obstruction.

During these episodes, increased right ventricular pressure results in right to left shunting through the VSD, because blood is shunted away from the pulmonary circulation, pulmonary arterial and left atrial pressures are decreased

Question 28

lowering the cutoff point causes?

Answer 28

more patients with the disease to test positive, decreasing the number of false negatives and increasing test sensitivity.

consequently, more patients without the disease will also test positive, resulting in an increased number of false positive and decreased specificity

Question 29

what is waterhouse-friderichsen syndrome

Answer 29

meningococcal meningitis is a rapidly progressive infection that can spread systemically (meningococcemia) and can lead to septic shock, multiorgan failure, and disseminated intravascular coagulation.

Meningococcemia is also associated with bilateral hemorrhagic infarction of the adrenal glands, which can result in acute adrenal insufficiency (waterhouse-friderichesen syndrome) with worsening shock and rapid clinical deterioration

Question 30

chronic kidney disease increases the risk for?

Answer 30

platelet dysfunction, which is thought to be due to inappropriately unregulated nitric oxide, causing decreased platelet adhesion, activation and aggregation.

Coagulation studies and platelet count are typically normal

Question 31

what is paranoid personality disorder

Answer 31

people with paranoid personality disorder exhibit a lifelong pattern of pervasive suspicion and distrust.

Unlike patients with psychotic disorders, they do not have fixed delusions and other psychotic symptoms

Question 32

what is internuclear opthalmoplegia

Answer 32

a disorder of impaired horizontal gaze caused by a lesion in the medial longitudinal fasciculus (MLF)

The affected eye (ipsilateral to the lesion) is unable to adduct while the contralateral eye is able to abduct (often with associated nystagmus)

Convergence and the pupillary light reflex are preserved because these pathways bypass the MLF

Question 33

Atrophic gastritis can result in?

Answer 33

profound hypochloridria, inadequate intrinsic factor production, vitamin B12 def, and elevated methylmalonic acid levels.

Once vitamin B12 replacement therapy is initiated, the reticulocyte count increases dramatically and peaks around 1 week; hemoglobin levels and erythrocyte counts rise more gradually and take up to 8 weeks to normalize

Question 34

what is the treatment of hepatic encephalopathy

Answer 34

lactulose (increases conversion of ammonia to ammonium) and rifaximin (decreases intraluminal ammonia production)

Question 35

what is histoplasmosis capsulatum

Answer 35

endemic to the Ohio and Mississippi River valleys and is found primarily in soil contaminated with bird or bath droppings.

It exists in tissues as an ovoid/round yeast predominantly within the intracellular space of macrophages.

Immunocompetent patients are often asymptomatic but can infrequently develop subacute pneumonia with hilar and mediastinal lymphadenopathy

Question 36

insulin can cause weight gain due to?

Answer 36

physiologic (increased peripheral glucose uptake, reduced renal loss of glucose) and behavioral (increased snacking in response to hypoglycemia, less rigorous attention to diet) factors.

Question 37

what are the labs for iron deficiency

Answer 37

decreased serum ferritin, increased total iron binding capacity (transferrin), and microcytic, hypochromic red blood cells

Question 38

what is a saddle pulmonary embolism

Answer 38

saddle pulmonary embolism straddles the bifurcation of the main pulmonary artery.

venous thromboembolism (pulmonary embolism or deep vein thrombosis) arises due to the Virchow triad of endothelial injury, venous stasis, and hypercoagulable state.

Malignancy causes a hypercoagulable state and is a strong risk factor for venous thromboembolism

Question 39

differential cyanosis (cyanosis affecting only the lower body) suggests?

Answer 39

right to left shunting across the ductus arteriosis.

In newborns, a potential cause of this pattern is persistent pulmonary hypertension of the newborn

Question 40

what is a glial scar

Answer 40

several months to years after ischemic brain infarction, the necrotic area appears as a cystic cavity surrounded by a wall composed of dense fibers formed by astrocytic processes (glial scar)

Question 41

what is primary hyperalodosteronism

Answer 41

increases distal Na reabsorption (secondary hypertension), leading to increased urinary excretion of H and K (metabolic alkalosis and hypokalemia).

Overt volume overload is not seen due to aldosterone escape, and serum Na concentration is typically normal due to preserved antidiuretic hormone function

Question 42

the majority of CO2 produced in the tissues is transported to the lungs as

Answer 42

bicarbonate ion (HCO3).

Within RBCs, the enzyme carbonic anhydrase forms HCO3 from CO2 and water.

The excess HCO3 is then transferred out of RBCs into the plasma via exchange with chloride ions (Cl-). This exchange is known as “chloride shift” and is the principal cause of high RBC chloride content in venous blood

Question 43

atheroembolic disease typically occurs after an invasive vascular procedure due to?

Answer 43

mechanical dislodgement of atherosclerotic plaque, resulting in the showering of cholesterol rich micro emboli into the circulation.

Needle shaped cholesterol clefts in affected vessels are diagnostic.

Commonly involved organs include the kidneys (acute kidney injury), skin (blue toe syndrome, livedo reticularis), gastrointestinal tract (bleeding, infarction) and CNS (stroke, amaurosis fugax)

Question 44

major adaptive immune mechanisms that prevent reinfection with the influenza virus include

Answer 44

anti-hemagglutinin antibodies

Question 45

presentation of sarcoidosis

Answer 45

presents with hilar adenopathy, pulmonary infiltrates, and skin findings (erythema nodosum).

Biopsy: noncaseating granulomas composed of epitheliod cells (activated macrophages) and giant multinucleated cells.

oral glucocorticoids are the initial treatment of choice

Question 46

most common adverse reaction of vancomycin

Answer 46

vancomycin infusion reaction (flushing, pruritus, erythematous rash) is the most common adverse reaction. It occurs due to rapid vancomycin infusion, which leads to the direct activation of mast cells (non-IgE mediated) and subsequent release of vasoactive mediators

Question 47

autoimmune hepatitis results from

Answer 47

an immune response against hepatic antigens, leading to a lymphoplasmacytic infiltrate in the portal and periportal regions of the liver.

Manifestations: fatigue, weight loss, nausea, and/or signs of acute hepatitis (jaundice, abdominal discomfort).

Labs: hepatocellular pattern of liver injury, anti-smooth muscle autoantibodies, and hypergammaglobulinemia

Question 48

first line treatment of wilson disease

Answer 48

penicillamine is a copper chelating agent; adverse effects include nephrotic syndrome (proteinuria) due to membranous nephropathy

Question 49

treatment of alcohol withdrawal

Answer 49

alcohol withdrawal should be considered in hospitalized patients who develop tremulousness, agitation, and elevated pulse and blood pressure within 48 hours following admission.

Benzodiazepines (lorazepam, diazepam, chlordiazepoxide) act as a substitute for the effects of alcohol on GABA receptors, preventing alcohol withdrawal from occuring

Question 50

what is subacute sclerosing panencephalitis

Answer 50

a rare complication of measles infection that occurs several years after apparent recovery from initial infection.

Oligoclonal bands of measles virus antibodies are found in the cerebrospinal fluid of these patients

Question 51

hydroxyurea MOA

Answer 51

hydroxyurea is used in patients with sickle cell disease to increased circulating fetal hemoglobin (Hb F) concentration. This reduces vasoocclusive crises and symptomatic anemia episodes

Question 52

histopath for glioblastoma multiforme

Answer 52

GMB is the most common primary brain tumor in adults.

Histopath showing increased vascularity and pseusopalisading tumor cells around areas of necrosis is highly characteristic.

Question 53

what mediates sarcoidosis

Answer 53

sarcoidosis is a CD4 T cell mediated disease, in which large numbers of CD4 lymphocytes release interferon gamma and tumor necrosis factor alpha to drive macrophage activation and granuloma formation.

Bronchoalveolar lavage fluid in pulmonary sarcoidosis demonstrates a lymphocytic predominance with a high CD4/CD8 ratio

Question 54

what is diffuse axonal injury

Answer 54

a type of traumatic brain injury that results from disruption of the white matter tracts

Microscopically, DAI is visible as widespread axonal swelling, most pronounced at the gray-white matter junction, with accumulation of transport proteins (amyloid precursor, alpha-synuclein) at the site of injury

Question 55

what is dilated cardiomyopathy

Answer 55

results from primary myocardial dysfunction leading to eccentric remodeling of the left ventricle.

Patients can develop left ventricular mural thrombus and are at risk for sudden cardiac death due to ventricular arrhythmia.

Familial dilated cardiomyopathy is typically inherited in an autosomal dominant pattern, and most commonly results from truncating mutations of the TTn gene that codes for the sarcomere protein titin

Question 56

common causes of acute pancreatitis

Answer 56

after gallstones, chronic alcohol use is the second most common cause of acute pancreatitis.

Macrocytosis and an AST:ALT ratio >2 are indirect indicators of chronic alcohol consumption.

Alcohol related macrocytosis can occur independently of folate deficiency

Question 57

What is mycobacterium leprae

Answer 57

the severity of leprosy, a systemic illness caused by mycobacterium leprae, depends on the strength of the cell mediated immune response, with tuberculoid leprosy representing the milder form (intact Th1 CMI response) and lepromatous leprosy, the more severe form (weak CMI response)

Question 58

secondary lactase deficiency can occur after?

Answer 58

inflammatory (celiac disease) or infectious (giardiasis) processes damage the microvilli of the small intestines.

Clinical presentation includes abdominal distension and cramping, flatulence, and diarrhea

Question 59

what is acute calculous cholecystitis

Answer 59

an acute inflammation of the gallbladder initiated by gallstone obstruction of the cystic duct. Subsequent steps in pathogenesis include mucosal disruption by lysolecithins, bile salt irritation of the luminal epithelium, prostaglandin release with transmural inflammation, gallbladder hypomotility, increased intraluminal pressure causing ischemia, and bacterial invasion

Question 60

what is cervical radiculopathy

Answer 60

typically results in neck and/or arm pain associated with neurologic deficits that follow a dermatomal/myotomal pattern.

Osteophytes that form due to degenerative changes in the vertebral joints can progressively narrow the neural foramina leading to nerve root compression

Question 61

poststreptococcal glomerulonephritis children versus adults

Answer 61

poststrep glomerulonephritis presents with edema, hypertension, and hematuria after a streptococcal infection.

Most children recover completely, but adult patients have a relatively poor prognosis and higher risk of chronic hypertension and renal insufficiency

Question 62

what is hypertensive emergency

Answer 62

severely elevated blood pressure (typically >180/120) with evidence of end organ damage.

In the kidneys, this can manifest as malignant neprhosclerosis, characterized by fibrinoid necrosis and hyperplastic arteriolosclerosis (“onion skin”).

A microangiopathic hemolytic anemia can occur due to erythrocyte fragmentation and platelet consumption at the narrowed arteriolar lumen

Question 63

histpath of alzheimer dementia

Answer 63

alzheimer dementia typically presents insidiously with memory loss (especially of recent events), executive dysfunction, and visuospatial impairment.

Classic histopath: amyloid plaques (central amyloid beta core surrounded by dystrophic neurites) and neurofibrillary tangles (aggregates of hyperphosphorylated tau protein)