# Clinical Cases: Small Intestine Disorders

## Case 1: Celiac Disease

### Patient Presentation
**Demographics:** 32-year-old female

**Chief Complaint:** Chronic diarrhea, bloating, and fatigue for 2 years

**History of Present Illness:** The patient reports 2 years of loose, pale, foul-smelling stools (3-4 per day) with excessive gas and bloating. She has lost 15 pounds despite normal appetite. She experiences persistent fatigue and has noticed a pruritic, blistering rash on her elbows and knees. Her menstrual periods have become irregular.

**Past Medical History:** Iron deficiency anemia treated with oral iron (poor response), hypothyroidism

**Family History:** Maternal aunt has "gluten problems," mother has type 1 diabetes

### Physical Examination
- **Vital Signs:** BP 108/68 mmHg, HR 88 bpm, BMI 19
- **General:** Thin female appearing fatigued
- **Abdomen:** Mildly distended, hyperactive bowel sounds, mild diffuse tenderness
- **Skin:** Groups of small vesicles and erosions on extensor surfaces of elbows and knees (dermatitis herpetiformis)
- **Musculoskeletal:** Tenderness over tibiae (suggest osteomalacia)

### Workup and Results
- **CBC:** Hemoglobin 10.2 g/dL, MCV 76 fL (microcytic)
- **Iron Studies:** Low ferritin, low iron, elevated TIBC
- **tTG-IgA:** 156 U/mL (markedly elevated, normal <20)
- **Total IgA:** Normal (ruling out IgA deficiency)
- **Upper Endoscopy with Duodenal Biopsies:** Scalloped duodenal folds, mosaic pattern; histology shows Marsh 3b (subtotal villous atrophy), crypt hyperplasia, >40 intraepithelial lymphocytes per 100 enterocytes
- **DEXA:** Osteopenia (T-score -1.8)

![Celiac Disease Histology](case_01_image.jpg)
*Duodenal biopsy showing villous atrophy, crypt hyperplasia, and increased intraepithelial lymphocytes characteristic of celiac disease (Marsh 3). Normal villous architecture is lost.*

**Image Source:** Wikimedia Commons, CC BY-SA 3.0

### Diagnosis
**Celiac Disease with Dermatitis Herpetiformis**

### Clinical Correlation
Celiac disease is an immune-mediated enteropathy triggered by gluten (gliadin in wheat, hordein in barley, secalin in rye) in genetically susceptible individuals carrying HLA-DQ2 or HLA-DQ8. Tissue transglutaminase deamidates gliadin peptides, creating epitopes that trigger CD4+ T cell responses. The resulting inflammation causes villous atrophy, reducing absorptive surface area and causing malabsorption. Iron deficiency anemia results from duodenal iron malabsorption. Dermatitis herpetiformis is the skin manifestation, pathognomonic for celiac disease. Untreated celiac disease increases risk for osteoporosis, infertility, and enteropathy-associated T-cell lymphoma.

### Treatment
- Strict, lifelong gluten-free diet (avoid wheat, barley, rye)
- Dietitian referral for education
- Monitor tTG-IgA levels (should normalize with adherence)
- Iron, calcium, and vitamin D supplementation
- Repeat endoscopy to confirm mucosal healing
- Screen first-degree relatives
- DEXA monitoring and treatment of osteopenia

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## Case 2: Carcinoid Syndrome

### Patient Presentation
**Demographics:** 58-year-old female

**Chief Complaint:** Episodic flushing, diarrhea, and wheezing for 6 months

**History of Present Illness:** The patient experiences sudden episodes of facial and upper body flushing lasting several minutes, often triggered by alcohol or stress. She has 5-6 watery stools daily. She has developed new-onset wheezing without prior asthma history. She reports fatigue and has noticed ankle swelling. She has lost 10 pounds.

**Past Medical History:** None significant

**Social History:** Occasional wine (now avoids due to flushing)

### Physical Examination
- **Vital Signs:** BP 110/70 mmHg, HR 96 bpm, BMI 24
- **General:** Female with visible facial telangiectasias
- **Cardiovascular:** Systolic murmur at left sternal border (tricuspid area); JVD present
- **Lungs:** Diffuse expiratory wheezes
- **Abdomen:** Hepatomegaly (liver edge 5 cm below costal margin), multiple firm nodules palpable
- **Extremities:** 2+ pitting edema bilaterally

### Workup and Results
- **24-hour Urine 5-HIAA:** 85 mg (markedly elevated, normal <6 mg)
- **Serum Chromogranin A:** 1,250 ng/mL (elevated)
- **CT Abdomen:** 2.5 cm enhancing mass in the ileum; multiple hypervascular liver metastases
- **Ga-68 DOTATATE PET/CT:** Intense uptake in ileal mass and liver lesions (somatostatin receptor positive)
- **Echocardiogram:** Thickened, restricted tricuspid valve with severe regurgitation; mild pulmonic stenosis

![Carcinoid Liver Metastases](case_02_image.jpg)
*CT scan demonstrating multiple hypervascular hepatic metastases (arrows) from a small bowel carcinoid tumor. Liver metastases allow serotonin to bypass hepatic metabolism and cause carcinoid syndrome.*

**Image Source:** Case courtesy of Radiopaedia.org

### Diagnosis
**Carcinoid Syndrome from Metastatic Small Bowel Neuroendocrine Tumor with Carcinoid Heart Disease**

### Clinical Correlation
Small bowel neuroendocrine tumors (carcinoids) arise from enterochromaffin cells and produce serotonin. Carcinoid syndrome only develops when tumor products reach systemic circulation, which typically requires liver metastases (bypassing hepatic first-pass metabolism). Serotonin causes: (1) flushing - vasoactive effects; (2) diarrhea - stimulation of intestinal motility and secretion; (3) wheezing - bronchoconstriction. Carcinoid heart disease affects right-sided valves (tricuspid, pulmonic) because serotonin is metabolized by the lungs before reaching the left heart. The diagnosis is confirmed by elevated urinary 5-HIAA (serotonin metabolite) and chromogranin A.

### Treatment
- Somatostatin analog: octreotide LAR 30 mg IM monthly (controls symptoms, may slow tumor growth)
- Telotristat (tryptophan hydroxylase inhibitor) for diarrhea refractory to octreotide
- Peptide receptor radionuclide therapy (177Lu-DOTATATE) for somatostatin receptor-positive metastatic disease
- Surgical debulking of liver metastases if feasible
- Cardiology evaluation for carcinoid heart disease; consider valve surgery if severe
- Perioperative octreotide to prevent carcinoid crisis during any procedures

---

## Case 3: Small Bowel Obstruction

### Patient Presentation
**Demographics:** 65-year-old female

**Chief Complaint:** Crampy abdominal pain, vomiting, and inability to pass gas for 24 hours

**History of Present Illness:** The patient developed crampy, periumbilical abdominal pain that comes in waves. She has vomited multiple times, initially bilious and now feculent. She has not passed gas or had a bowel movement in 24 hours. The pain is worsening.

**Past Medical History:** Hysterectomy 15 years ago for fibroids, appendectomy in childhood

**Surgical History:** Total abdominal hysterectomy, open appendectomy

### Physical Examination
- **Vital Signs:** BP 105/65 mmHg, HR 112 bpm, Temperature 37.8C
- **General:** Female in moderate distress, appears dehydrated
- **Abdomen:** Distended, tympanitic, diffuse tenderness without rebound or guarding; well-healed lower midline scar; high-pitched bowel sounds with rushes
- **Rectal:** Empty vault, no masses

### Workup and Results
- **CBC:** WBC 12,500 with left shift
- **BMP:** BUN 35, Cr 1.4, K 3.2 (hypokalemic from vomiting)
- **Lactate:** 1.8 mmol/L (mildly elevated)
- **Abdominal X-ray:** Multiple dilated small bowel loops with air-fluid levels; minimal colonic gas
- **CT Abdomen with Contrast:** Small bowel obstruction with transition point in the pelvis; dilated proximal loops, decompressed distal bowel; no pneumatosis or free air; likely adhesive band

![Small Bowel Obstruction CT](case_03_image.jpg)
*CT scan demonstrating small bowel obstruction with dilated, fluid-filled loops of proximal small bowel and a transition point (arrow) where bowel caliber abruptly changes to decompressed distal loops, consistent with adhesive obstruction.*

**Image Source:** Case courtesy of Radiopaedia.org

### Diagnosis
**Adhesive Small Bowel Obstruction**

### Clinical Correlation
Adhesions from prior abdominal surgery are the most common cause of small bowel obstruction (60-70% of cases). The patient's previous hysterectomy created adhesive bands that can kink or compress bowel. Proximal to the obstruction, bowel dilates as gas and secretions accumulate. The third-spacing of fluid causes dehydration and electrolyte abnormalities. Complete obstruction prevents passage of gas and stool (obstipation). The transition point on CT identifies where dilated bowel meets decompressed bowel. Signs concerning for strangulation include fever, tachycardia, elevated lactate, and peritoneal signs.

### Treatment
- NPO, nasogastric tube placement for decompression
- Aggressive IV fluid resuscitation with electrolyte replacement
- Serial abdominal examinations
- Gastrografin (water-soluble contrast) challenge: if contrast reaches colon within 24 hours, resolution likely; if not, surgery indicated
- Close monitoring for signs of strangulation (would mandate immediate surgery)
- If no improvement in 48-72 hours or clinical deterioration, surgical exploration with adhesiolysis