A d-xylose test was requested on a patient with a history of long-standing steatorrhea, ‘5’ hour urine sample showed <4.0 gm excretion after giving 25 gm of d-xylose. The most likely diagnosis is
**Core Concept**
The d-xylose test is a diagnostic tool used to assess the intestinal absorption of carbohydrates, specifically d-xylose, a monosaccharide. It is often employed in patients with suspected malabsorption, particularly those with chronic diarrhea or steatorrhea.
**Why the Correct Answer is Right**
In this scenario, the patient has a history of long-standing steatorrhea, indicating malabsorption of fats. The d-xylose test measures the intestinal absorption of d-xylose, which is absorbed in the proximal small intestine. A low urine excretion of d-xylose (<4.0 gm) after 5 hours suggests impaired intestinal absorption. This is consistent with a diagnosis of **celiac disease**, a chronic autoimmune disorder that causes malabsorption due to inflammation and damage to the small intestine. The small intestine's ability to absorb d-xylose is compromised in celiac disease, leading to the observed low excretion.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not provided. Please ensure the question has all options.
**Option B:** While other conditions like pancreatic insufficiency can cause malabsorption, they typically present with symptoms like abdominal pain, weight loss, and greasy stools. The d-xylose test is more specific for intestinal malabsorption, making this option less likely.
**Option C:** This option is not provided. Please ensure the question has all options.
**Clinical Pearl / High-Yield Fact**
Celiac disease is a common cause of malabsorption in patients with chronic diarrhea or steatorrhea. The d-xylose test is a useful diagnostic tool in these patients, but it should be interpreted in conjunction with clinical history and other diagnostic tests.
**Correct Answer:** B. Pancreatic insufficiency.