Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.
A 32-year-old woman is evaluated for a 2-month history of weight loss, abdominal cramping, and loose stools. Her stools are malodorous, but she has not noted any blood associated with her bowel movements. Although her appetite is good, she has lost 3.2 kg (7.0 lb). She has an 8-year history of diffuse cutaneous systemic sclerosis.
On physical examination, temperature is normal, blood pressure is 146/92 mm Hg, pulse rate is 94/min, and respiration rate is 16/min. BMI is 19. Cardiopulmonary examination is normal. The abdomen is soft and nontender with normal bowel sounds. Diffuse skin thickening of the face, anterior chest, and distal extremities is noted as well as sclerodactyly and multiple healed digital pits. There is no rash. Muscle strength and reflexes are normal.
Laboratory studies:
| Albumin | 2.6 g/dL (26 g/L) |
| Alanine aminotransferase | Normal |
| Aspartate aminotransferase | Normal |
| Total bilirubin | Normal |
| Lipase | Normal |
| Urinalysis | Normal |
Which of the following is the most appropriate diagnostic test to perform next?
A. Colonoscopy
B. CT of the abdomen and pelvis with contrast
C. Endoscopic retrograde cholangiopancreatography
D. Glucose hydrogen breath test
MKSAP Answer and Critique
The correct answer is D. Glucose hydrogen breath test.
A glucose hydrogen breath test is indicated. This patient has an 8-year history of diffuse cutaneous systemic sclerosis (DcSSc) and now presents with weight loss, abdominal cramping, and loose stools. She is at high risk for developing malabsorption from bacterial overgrowth (also known as blind loop syndrome) due to altered peristalsis caused by fibrosis associated with her underlying disease. She has unexplained weight loss as well as loose stools without any increase in symptoms of dysphagia, nausea, or vomiting. The most appropriate study for her evaluation at this time is the glucose hydrogen breath test. The gold standard for the detection of bacterial overgrowth is small bowel aspiration, but this study is not frequently performed because it is invasive. By comparison, the glucose hydrogen breath test is noninvasive and has a high sensitivity and specificity. Barium study may also be done to confirm these findings, but obtaining a CT scan at this point is unnecessary and costly. MRI may also be useful in the future for assessment of disease and exclusion of other pathologies.
She does not have bloody bowel movements or colitis, and performing a colonoscopy is unlikely to lead to the correct diagnosis because the primary pathology is in the small bowel and not the colon.
Endoscopic retrograde cholangiopancreatography is the diagnostic test of choice for suspected pancreatic or extrahepatic biliary tract pathology. She has no evidence of biliary tract blockage or pancreatic disease.
Key Point
- In patients with systemic sclerosis, malabsorption due to bacterial overgrowth is evaluated by obtaining a glucose hydrogen breath test.
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