What happens to the iron ions that are released when red blood cells (RBCs) are broken down?

Describe the relationship between preload, afterload, and contractility. Include discussion of the Frank-Starling law as it relates to these relationships.

Lactose Intolerance 1. Background Definition: Inability to digest lactose, the main carbohydrate in milk and dairy products, due to lactase enzyme deficiency in the brush border of the small intestine. Pathophysiology: Undigested lactose remains in the intestinal lumen → osmotic diarrhea and bacterial fermentation → gas, bloating, and cramping. Types: Primary (genetic): Gradual loss of lactase after childhood (most common worldwide). Secondary (acquired): Due to mucosal injury (celiac disease, gastroenteritis, Crohn disease). Congenital: Rare, autosomal recessive, presents in infancy. Epidemiology: Very common globally; affects up to 90% of Asian, African, and Native American populations; less common in Northern Europeans. 2. History Symptoms: Bloating, flatulence, crampy abdominal pain, and watery diarrhea after ingestion of milk or dairy products. Symptoms occur 30 minutes to 2 hours after lactose ingestion. Risk factors: Increasing age, certain ethnic backgrounds, recent intestinal infection, or small bowel disease. Relief: Avoidance of dairy eliminates symptoms. 3. Exam Findings Usually benign; may show mild abdominal distension or hyperactive bowel sounds. Signs of dehydration if diarrhea severe. Otherwise normal physical exam. 4. Making the Diagnosis Gold standard: Hydrogen breath test — elevated breath hydrogen after lactose load indicates malabsorption. Common alternative: Lactose elimination and re-challenge — symptom resolution after lactose avoidance confirms diagnosis. Supportive tests: Stool acidity test (infants): Low stool pH due to fermentation. Small bowel biopsy: Rarely needed; shows decreased lactase activity (used to rule out secondary causes). 5. Management A. Dietary Lactose restriction or use of lactose-free dairy products. Many patients tolerate small amounts of milk with meals. B. Supplements Lactase enzyme replacement before dairy intake (e.g., Lactaid). Calcium and vitamin D supplementation to prevent deficiency in those avoiding dairy. C. Treat underlying cause (if secondary) Address intestinal mucosal disease (e.g., celiac disease, Crohn disease, gastroenteritis recovery).   A 23-year-old woman reports several months of bloating, flatulence, and crampy abdominal pain that occur about 1 hour after drinking milk or eating ice cream. She denies fever, weight loss, or blood in her stool. Physical examination is normal. Which of the following is the most appropriate diagnostic test to confirm lactose intolerance?

Peptic Ulcer Disease (PUD) 1. Background Definition: Mucosal erosions ≥5 mm in the stomach or duodenum that penetrate the muscularis mucosa, usually due to acid–pepsin injury and impaired mucosal defense. Pathophysiology: Helicobacter pylori infection → increased gastric acid + inflammation → mucosal damage. NSAID use → prostaglandin inhibition → decreased mucus and bicarbonate production. Less common causes: Zollinger-Ellison syndrome, physiologic stress, smoking. Epidemiology: Duodenal ulcers more common than gastric. Peak incidence 30–60 years; risk increases with NSAID use and H. pylori prevalence. Complications: Bleeding, perforation, gastric outlet obstruction, malignancy (gastric only). 2. History Typical symptoms: Epigastric pain (burning, gnawing) related to meals. Duodenal ulcer: Pain relieved by food, returns 2–3 h after eating. Gastric ulcer: Pain worsens with food. Associated findings: Bloating, nausea, early satiety, melena, hematemesis in bleeding ulcers. Risk factors: H. pylori infection, chronic NSAID or aspirin use, smoking, corticosteroids, stress, older age, prior ulcer. 3. Exam Findings Mild epigastric tenderness. Occult blood on rectal exam if bleeding. Severe pain with guarding or rebound suggests perforation. 4. Making the Diagnosis Gold standard: Upper endoscopy (EGD) with biopsy — confirms ulcer, rules out malignancy, and allows H. pylori testing. Required in patients with alarm features (age > 60, weight loss, anemia, vomiting, GI bleeding, early satiety). Commonly used tests: Noninvasive H. pylori testing (urea breath test, stool antigen) for low-risk patients. Barium study if endoscopy unavailable, but less sensitive. Notes: Gastric ulcers should always be biopsied to exclude carcinoma. If initial endoscopy negative and suspicion high, consider Zollinger-Ellison syndrome (fasting gastrin). 5. Management A. Lifestyle / Non-pharmacologic Stop NSAIDs/aspirin when possible. Avoid smoking, alcohol, caffeine. Eat smaller meals; manage stress. B. Medication Eradicate H. pylori (if positive): Triple therapy (14 days): PPI + clarithromycin + amoxicillin (or metronidazole if penicillin-allergic). Quadruple therapy: PPI + bismuth + tetracycline + metronidazole (preferred if clarithromycin resistance or prior macrolide exposure). Acid suppression: PPI (omeprazole, pantoprazole) for 4–8 weeks after therapy. H2 blocker as alternative if mild disease. NSAID-related ulcers: Stop NSAID; start PPI or misoprostol if NSAIDs must continue. C. Complications / Procedures Bleeding: Endoscopic coagulation or clipping; IV PPI infusion afterward. Perforation: Surgical repair. Refractory or recurrent ulcers: Confirm eradication, exclude malignancy or gastrinoma.   Question A 45-year-old man presents with several weeks of epigastric pain that improves after meals but returns a few hours later. He takes ibuprofen daily for chronic back pain. He denies vomiting, hematemesis, or melena. Physical examination shows mild epigastric tenderness without peritoneal signs. Which of the following is the most appropriate next diagnostic test to confirm the underlying cause of this patient’s condition?

MAFLD / MASH (Metabolic Dysfunction–Associated Fatty Liver Disease / Steatohepatitis) 1. Background MAFLD: Hepatic steatosis in patients with metabolic dysfunction (obesity, diabetes, dyslipidemia, or insulin resistance). MASH: Inflammatory subtype with hepatocellular injury and fibrosis. Replaces NAFLD/NASH terminology; alcohol intake no longer used to exclude diagnosis. Pathophysiology: Insulin resistance → increased fatty acid influx → triglyceride accumulation → oxidative stress → inflammation and fibrosis. Epidemiology: Most common liver disease in the U.S.; associated with metabolic syndrome, obesity, and diabetes. 2. History Often asymptomatic or presents with fatigue or mild RUQ discomfort. Risk factors: Central obesity, type 2 diabetes, dyslipidemia, hypertension, PCOS. Medications that worsen steatosis: corticosteroids, methotrexate, tamoxifen, amiodarone. 3. Exam Findings Mild hepatomegaly early. Advanced disease: jaundice, ascites, spider angiomas, palmar erythema, gynecomastia, splenomegaly. 4. Diagnosis Labs Mild elevation of AST/ALT (usually AST Late (fibrosis): AST > ALT Normal bilirubin and ALP unless advanced. Screen for metabolic syndrome (A1c, fasting glucose, lipids). Imaging Ultrasound: Increased echogenicity (“bright liver”). FibroScan (elastography): Measures fibrosis noninvasively. CT/MRI: Detects fat but not inflammation. Biopsy (if needed): Steatosis with ballooning degeneration, Mallory-Denk bodies, lobular inflammation, and pericellular fibrosis (MASH pattern). Diagnostic Criteria (2023): Evidence of hepatic steatosis plus one of: Overweight/obesity Type 2 diabetes ≥2 features of metabolic dysregulation (↑ waist circumference, dyslipidemia, insulin resistance, ↑ CRP, etc.) 5. Management Lifestyle (First-line) Weight loss ≥10% → improves steatohepatitis and fibrosis. Diet: Mediterranean or low-carbohydrate. Exercise: ≥150 minutes/week moderate activity. Avoid alcohol and hepatotoxic drugs. Pharmacologic Pioglitazone: For biopsy-proven MASH with T2DM. GLP-1 agonists (semaglutide): Reduce steatosis and promote weight loss. Vitamin E (800 IU/day): For non-diabetic MASH. No FDA-approved drug yet (as of 2025). Comorbidity Management Optimize glucose, lipids, and blood pressure (statins are safe). Monitoring / Surveillance Elastography every 1–2 years to assess fibrosis. HCC surveillance (ultrasound ± AFP every 6 months) if cirrhosis develops. Liver transplant for end-stage disease. Question A 49-year-old woman with obesity, hypertension, and type 2 diabetes presents for evaluation of mild fatigue. She denies alcohol use. Laboratory studies show: Test Result Reference Range ALT 68 U/L (7–56 U/L) AST 56 U/L (10–40 U/L) Alkaline phosphatase 98 U/L (44–147 U/L) Total bilirubin 0.8 mg/dL (0.2–1.2 mg/dL) Fasting glucose 152 mg/dL (70–99 mg/dL) Hemoglobin A1c 7.4% (

Choledocholithiasis 1. Background Definition: Presence of one or more gallstones in the common bile duct (CBD), leading to biliary obstruction. Pathophysiology: Secondary stones (most common): Migrated from the gallbladder via the cystic duct. Primary stones: Form within the CBD due to stasis or infection. Obstruction → bile stasis → ductal dilation and ↑ pressure → potential cholangitis or pancreatitis. Epidemiology: Occurs in ~10–15% of patients with gallstones. More common in middle-aged women and in patients with a history of cholelithiasis or cholecystectomy. 2. History Symptoms: RUQ or epigastric pain (colicky or steady), often following a fatty meal. Jaundice (fluctuating or progressive). Dark urine and pale stools due to conjugated hyperbilirubinemia. Nausea and vomiting. May be asymptomatic and discovered incidentally (e.g., elevated liver enzymes). Complications: Cholangitis: Fever, jaundice, RUQ pain (Charcot triad). Gallstone pancreatitis: Epigastric pain radiating to back with elevated lipase. 3. Exam Findings RUQ tenderness or mild epigastric tenderness. Jaundice and scleral icterus (key differentiator from uncomplicated cholecystitis). Murphy sign usually negative unless concurrent cholecystitis. Fever or hypotension if cholangitis develops (Charcot triad or Reynolds pentad). 4. Making the Diagnosis A. Laboratory Findings Cholestatic pattern: ↑ ALP and GGT (disproportionate to AST/ALT). ↑ Direct (conjugated) bilirubin. Mild elevation of AST/ALT possible. If pancreatitis: Elevated amylase/lipase. B. Imaging Test Role Ultrasound (first-line) Detects gallstones and dilated CBD (>6 mm); may not visualize CBD stones directly. MRCP (magnetic resonance cholangiopancreatography) Noninvasive, highly sensitive for CBD stones. Endoscopic ultrasound (EUS) Alternative for stone detection if MRCP unavailable or indeterminate. ERCP (endoscopic retrograde cholangiopancreatography) Gold standard for diagnosis and treatment (stone extraction). Used when diagnosis is likely or confirmed. C. Distinguishing Features Condition Key Findings Cholelithiasis Stones confined to gallbladder, no jaundice or LFT elevation Cholecystitis RUQ pain + fever, normal or mildly elevated LFTs, no duct dilation Choledocholithiasis Jaundice, ↑ ALP & bilirubin, dilated CBD Cholangitis Choledocholithiasis + infection (fever, leukocytosis, Charcot triad) 5. Management A. Initial Care NPO, IV fluids, analgesia, and broad-spectrum antibiotics if infection suspected. Correct coagulopathy and fluid/electrolyte imbalances. B. Definitive Therapy ERCP with sphincterotomy and stone extraction (diagnostic and therapeutic). Laparoscopic cholecystectomy after duct clearance to prevent recurrence (unless already removed). C. Alternatives Percutaneous transhepatic cholangiography (PTC): For patients not candidates for ERCP. Intraoperative cholangiography: Detects stones during cholecystectomy. D. Complications Acute cholangitis Gallstone pancreatitis Biliary cirrhosis (from chronic obstruction) E. Prevention Removal of gallbladder if source of recurrent stones. Adequate hydration and healthy diet to reduce stone formation risk. Question A 52-year-old woman presents with right upper quadrant abdominal pain, jaundice, and nausea for the past two days. She had a laparoscopic cholecystectomy 3 years ago. Her temperature is 99.9°F (37.7°C), blood pressure 118/72 mm Hg, and pulse 88/min. Physical exam reveals scleral icterus and mild right upper quadrant tenderness without guarding. Laboratory studies: AST: 96 U/L ALT: 112 U/L ALP: 480 U/L Total bilirubin: 5.2 mg/dL (direct 4.7 mg/dL) Ultrasound shows a dilated common bile duct (9 mm) without gallbladder. Which of the following is the most appropriate next step in management?

Eosinophilic Esophagitis (EoE) 1. Background Definition: Chronic, immune-mediated inflammation of the esophagus characterized by ≥15 eosinophils per high-power field on biopsy. Pathophysiology: Triggered by food or environmental allergens causing Th2-driven eosinophilic infiltration, fibrosis, and stricture formation. Epidemiology: Increasing prevalence; most common in young to middle-aged men and individuals with atopic conditions (asthma, eczema, allergic rhinitis). Key associations: Atopy, food allergies (milk, egg, soy, wheat, nuts, seafood). 2. History Symptoms: Solid-food dysphagia, food impaction, chest pain or heartburn refractory to PPIs. Children: Feeding difficulty, vomiting, or failure to thrive. Risk factors: Personal/family atopy, male sex, chronic GERD-like symptoms unresponsive to therapy. 3. Exam Findings Physical exam: Usually normal; may see skin or nasal signs of allergy. Endoscopy findings: Concentric rings (“trachealization”) Linear furrows White exudates or plaques Fragile, narrowed lumen 4. Making the Diagnosis Gold standard: Upper endoscopy with biopsy showing ≥15 eosinophils/HPF. Note: Diagnosis requires persistence of eosinophilia after an adequate PPI trial to exclude PPI-responsive esophageal eosinophilia. Other testing: Allergy evaluation may help identify food triggers but is not required for diagnosis. 5. Management A. Lifestyle/Diet Eliminate common food allergens (empiric 6-food elimination: milk, egg, soy, wheat, nuts, seafood). Consider dietitian referral. B. Medication First line: Topical corticosteroids (swallowed fluticasone or budesonide). PPIs may reduce inflammation in some cases. C. Procedures Endoscopic dilation for fixed strictures causing significant dysphagia. Repeat endoscopy to assess response if symptoms persist. Question A 25-year-old man with a history of asthma and seasonal allergies presents with several months of intermittent solid-food dysphagia and two recent episodes of food impaction. He reports no odynophagia, weight loss, or hematemesis. A trial of omeprazole for 8 weeks provided no relief. Upper endoscopy reveals concentric rings and linear furrows in the mid-esophagus. Biopsies show 25 eosinophils per high-power field. Which of the following is the most appropriate initial treatment for this patient’s condition?

Diverticulitis 1. Background Definition: Inflammation and microperforation of a colonic diverticulum, most commonly in the sigmoid colon. Pathophysiology: Diverticula form at weak points in the colonic wall where vasa recta penetrate the muscular layer (diverticulosis). Fecalith obstruction or microperforation → localized inflammation and infection = diverticulitis. Epidemiology: Common in adults >50 years. Risk factors: low-fiber diet, obesity, physical inactivity, NSAID use, and advancing age. Complications: Abscess, perforation, peritonitis, fistula (colovesical most common), or obstruction. 2. History Symptoms: Left lower quadrant (LLQ) abdominal pain (most common). Fever, nausea/vomiting, change in bowel habits (constipation or diarrhea). Urinary symptoms (dysuria, pneumaturia) may indicate colovesical fistula. History clues: Prior episodes suggest recurrent diverticulitis. Use of NSAIDs or opioids may increase risk of complications. 3. Exam Findings Typical: LLQ tenderness, low-grade fever, mild distension. Possible: Palpable mass (abscess), guarding, or rebound tenderness if perforation or peritonitis. Rectal exam: May show occult blood; gross bleeding is rare. Severe findings: Tachycardia, hypotension (suggest complicated diverticulitis). 4. Making the Diagnosis Gold standard imaging: CT abdomen and pelvis with IV contrast — shows colonic wall thickening, fat stranding, and possible abscess or perforation. Laboratory: Leukocytosis, elevated CRP. Plain X-ray: May show ileus or free air if perforation. Avoid colonoscopy or barium enema during acute episode due to risk of perforation. Colonoscopy recommended 6–8 weeks after recovery to exclude malignancy. 5. Management A. Uncomplicated Diverticulitis Outpatient treatment: Clear liquid diet → advance as tolerated. Oral antibiotics covering gram-negative and anaerobes (e.g., amoxicillin–clavulanate or ciprofloxacin + metronidazole). Close follow-up within 2–3 days. Inpatient indications: Severe pain, high fever, vomiting, leukocytosis, immunosuppression, or inability to tolerate PO intake. B. Complicated Diverticulitis IV antibiotics and hospitalization. CT-guided percutaneous drainage for abscess >3 cm. Surgical intervention for perforation, peritonitis, obstruction, or recurrent complicated episodes (possible sigmoid colectomy). C. Prevention High-fiber diet, adequate hydration, weight control, and avoidance of NSAIDs.   Question A 56-year-old woman presents with 2 days of constant left lower quadrant abdominal pain and mild fever. She reports nausea but no vomiting and is tolerating oral fluids. Her vital signs are stable. Physical examination shows localized left lower quadrant tenderness without guarding or rebound. Laboratory studies reveal a mild leukocytosis. CT of the abdomen and pelvis demonstrates localized sigmoid wall thickening and pericolic fat stranding without abscess or perforation. Which of the following is the most appropriate initial management for this patient?

Hemorrhoids 1. Background Definition: Dilated and symptomatic venous cushions of the hemorrhoidal plexus in the anal canal. Anatomy: Internal hemorrhoids: Above the dentate line; covered by columnar mucosa; visceral innervation → painless. External hemorrhoids: Below the dentate line; covered by squamous epithelium; somatic innervation → painful when thrombosed. Pathophysiology: Increased venous pressure from straining, constipation, prolonged sitting, pregnancy, portal hypertension, or obesity causes engorgement and prolapse of venous plexus. Epidemiology: Common in adults 45–65 years; prevalence rises with age and constipation. 2. History Internal hemorrhoids: Painless bright red rectal bleeding (on toilet paper or dripping after defecation). Mucosal prolapse or soiling in advanced grades. External hemorrhoids: Painful perianal lump (thrombosis) with acute onset after straining or prolonged sitting. May have pruritus or swelling but typically no bleeding unless ulcerated. Risk factors: Chronic constipation, prolonged sitting, low-fiber diet, pregnancy, portal hypertension, or frequent heavy lifting. 3. Exam Findings Inspection: External: Visible bluish perianal mass if thrombosed. Internal: Not always visible unless prolapsed (use anoscopy). Digital rectal exam: May reveal soft compressible masses or exclude other causes (fissure, abscess, tumor). Anoscopy: Confirms diagnosis and grades internal hemorrhoids: Grade I: No prolapse, bleeds only Grade II: Prolapse with straining, reduces spontaneously Grade III: Prolapse requires manual reduction Grade IV: Irreducible, may thrombose or ulcerate 4. Making the Diagnosis Clinical diagnosis: Based on history and physical exam (inspection, DRE, anoscopy). Exclude other causes of bleeding: Colonoscopy indicated in: Age ≥45 or risk factors for colorectal cancer Iron-deficiency anemia or melena Atypical bleeding (dark stool, mixed blood, systemic symptoms) Laboratory: CBC if chronic bleeding suspected. 5. Management A. Conservative (First-line for most) Dietary fiber supplementation and increased fluids. Avoid prolonged straining; use stool softeners (docusate). Topical therapies: Witch hazel, hydrocortisone, or anesthetic creams for short-term relief. Sitz baths for comfort. B. Office Procedures (Persistent Grade I–III) Rubber band ligation (most effective for internal hemorrhoids). Sclerotherapy or infrared coagulation if not surgical candidates. C. Surgical Management Excisional hemorrhoidectomy: For large Grade III–IV internal hemorrhoids or recurrent thrombosed external hemorrhoids. Thrombosed external hemorrhoid: Excision within 72 hours provides rapid pain relief. D. Prevention High-fiber diet, hydration, prompt defecation, and avoidance of prolonged sitting or straining.   Question A 42-year-old man presents with severe anal pain that began suddenly after straining during a bowel movement this morning. He reports mild swelling but no rectal bleeding. Physical examination reveals a tender, bluish perianal nodule below the dentate line. Which of the following is the most appropriate management?

Celiac Disease (Gluten-Sensitive Enteropathy) 1. Background Definition: An autoimmune-mediated intestinal disorder triggered by dietary gluten (wheat, barley, rye) in genetically susceptible individuals. Pathophysiology: Ingestion of gluten → immune response against tissue transglutaminase (tTG) → villous atrophy and crypt hyperplasia in the small intestine → malabsorption. Genetics: Strongly associated with HLA-DQ2 and HLA-DQ8 alleles. Epidemiology: Affects ~1% of the population; higher prevalence in Northern European ancestry and patients with autoimmune diseases (type 1 diabetes, autoimmune thyroiditis). Complications: Malnutrition, iron-deficiency anemia, osteoporosis, infertility, dermatitis herpetiformis, and increased risk of intestinal T-cell lymphoma. 2. History Symptoms (classic form): Chronic diarrhea, steatorrhea, weight loss, abdominal bloating, and fatigue. Atypical/non-GI manifestations: Iron-deficiency anemia, osteoporosis, neuropathy, short stature, delayed puberty, infertility. Dermatologic: Dermatitis herpetiformis — pruritic papulovesicular rash on extensor surfaces. Onset: May appear in childhood or adulthood; often improves when gluten is avoided. Risk factors: Family history, autoimmune diseases, selective IgA deficiency. 3. Exam Findings May be normal in mild cases. Signs of malabsorption: pallor (anemia), glossitis, muscle wasting, or peripheral edema (hypoproteinemia). Rash consistent with dermatitis herpetiformis (elbows, knees, buttocks). 4. Making the Diagnosis Initial test: Serologic testing — tissue transglutaminase IgA (tTG-IgA) and total IgA (to rule out IgA deficiency). Confirmatory test (gold standard): Small bowel biopsy via upper endoscopy showing villous atrophy, crypt hyperplasia, and intraepithelial lymphocytosis. If IgA deficient: Use IgG-based tests (deamidated gliadin peptide IgG or tTG-IgG). HLA typing (DQ2/DQ8): Negative result effectively rules out celiac disease (useful if diagnosis uncertain). Note: Patients must be consuming gluten before testing to avoid false negatives. 5. Management A. Dietary Strict lifelong gluten-free diet (avoid wheat, barley, rye). Nutritional counseling and monitoring for deficiencies (iron, folate, B12, vitamin D, calcium). B. Medical Dermatitis herpetiformis: Dapsone for symptomatic relief, plus gluten-free diet. Treat associated deficiencies (iron, folate, vitamin D, calcium). C. Monitoring Follow-up tTG-IgA titers to assess dietary adherence. Bone density screening (osteoporosis risk). Rare refractory cases may require corticosteroids or immunosuppressants.   Question A 29-year-old woman with chronic diarrhea, bloating, and weight loss undergoes upper endoscopy after positive celiac serology. Duodenal biopsies are obtained. Which of the following histologic findings is most characteristic of this patient’s disease?