Gastroenterology and Hepatology Flashcards

A 48-year-old male with a history of iron deficiency anemia and intermittent bloating presents for evaluation. He reports no significant alcohol use or medication changes. Which of the following is the most appropriate initial serologic test to screen for celiac disease?

Answer: IgA anti-tissue transglutaminase (tTG) antibody

The most sensitive and specific initial blood test for celiac disease is the IgA anti-tissue transglutaminase (tTG) antibody test. It is recommended as the first-line screening tool. An endoscopy with biopsy is the gold standard for confirmation but is not the initial screening test. ASCA is associated with Crohn's disease, and a hydrogen breath test is used for lactose intolerance or small intestinal bacterial overgrowth.

A patient's hepatitis B serology results are as follows: HBsAg: Negative, Anti-HBs: Positive, Anti-HBc (Total): Positive, IgM Anti-HBc: Negative. What is the correct interpretation of these results?

Answer: Immunity due to resolved natural infection

This pattern indicates immunity from a past, resolved natural infection. The presence of Anti-HBs confers immunity. The presence of total Anti-HBc indicates previous exposure to the core antigen, which only occurs during natural infection, not vaccination. Immunity from vaccination would show a positive Anti-HBs but a negative Anti-HBc. Acute infection would have a positive HBsAg and positive IgM Anti-HBc. Chronic infection would have a positive HBsAg.

A 65-year-old male with decompensated cirrhosis due to alcohol use presents with moderate, new-onset ascites. His renal function is normal, and his serum potassium is 4.2 mEq/L. According to current guidelines, what is the most appropriate initial diuretic regimen?

Answer: Spironolactone 100 mg and furosemide 40 mg daily

The standard and recommended initial management for ascites in cirrhosis is dual-diuretic therapy with an aldosterone antagonist and a loop diuretic. The typical starting doses are spironolactone 100 mg and furosemide 40 mg daily. This combination helps to counteract the hyperaldosteronism of cirrhosis and maintain normokalemia. Starting with spironolactone alone is an option, but combination therapy is often preferred for more effective and rapid natriuresis. Furosemide monotherapy is less effective and not recommended as initial treatment.

A 34-year-old female is diagnosed with moderate-to-severe ulcerative colitis. She has failed to respond to a course of oral and rectal mesalamine and required a course of corticosteroids for a recent flare. Which of the following medication classes is an appropriate next step for inducing and maintaining remission?

Answer: An anti-TNF biologic agent (e.g., infliximab)

For patients with moderate-to-severe ulcerative colitis who are refractory to or dependent on corticosteroids, the next step in management is typically the initiation of a biologic agent, such as an anti-TNF agent (infliximab, adalimumab), an anti-integrin (vedolizumab), or an IL-12/23 inhibitor (ustekinumab). These medications are effective for both inducing and maintaining remission. Loperamide is for symptomatic control of diarrhea only. Proton pump inhibitors are not used for treating IBD. Antibiotics have a limited role, primarily for infectious complications.

According to the most recent guidelines from the U.S. Preventive Services Task Force (USPSTF) and the American Cancer Society (ACS), at what age should asymptomatic individuals with an average risk for colorectal cancer begin screening?

Answer: 45

Due to a rising incidence of colorectal cancer in younger adults, major organizations including the USPSTF and the American Cancer Society have lowered the recommended age to begin screening for average-risk individuals from 50 to 45. Individuals with a family history or other risk factors may need to start screening earlier.

A 59-year-old patient on treatment for latent tuberculosis with isoniazid develops fatigue, nausea, and right upper quadrant discomfort. Laboratory tests reveal an AST of 350 U/L and an ALT of 410 U/L (baseline was normal). Which of the following patterns of liver injury is most characteristically associated with isoniazid toxicity?

Answer: Hepatocellular injury

Isoniazid (INH) is a well-known cause of drug-induced liver injury (DILI). The classic presentation is a hepatocellular pattern of injury, which mimics acute viral hepatitis. This is characterized by a significant elevation in aminotransferases (AST and ALT), often more than 10 times the upper limit of normal, as seen in this patient. A cholestatic pattern would involve a predominant rise in alkaline phosphatase and bilirubin. While other patterns can occur, hepatocellular injury is the most common and characteristic form of INH hepatotoxicity.