**Question:** False positive urinary D-xylose test is seen in:

A. Diabetes mellitus
B. Liver disease
C. Pregnancy
D. Malabsorption syndromes

**Core Concept:**
The D-xylose test is a diagnostic tool used to assess small bowel absorption, specifically the assessment of lactase activity. D-xylose is a simple sugar that is absorbed by the small intestine, and a deficiency in lactase, the enzyme that catalyzes the hydrolysis of lactose to glucose and galactose, can lead to malabsorption of D-xylose.

**Why the Correct Answer is Right:**
The correct answer is liver disease (option B) because liver disease can cause impaired D-xylose absorption due to reduced production of lactase in the liver. In liver disease, there is often a decrease in the synthesis of lactase, leading to a false positive result in the D-xylose test.

**Why Each Wrong Option is Incorrect:**
A. Diabetes mellitus (option A) typically causes hyperglycemia, hyperosmolarity, and polyuria but does not lead to a false positive D-xylose test.

C. Pregnancy (option C) does not inherently affect lactase production or absorption, so a false positive D-xylose test is not commonly seen in pregnancy.

D. Malabsorption syndromes (option D) typically cause malabsorption of other nutrients and not specifically D-xylose, leading to a false positive D-xylose test.

**Clinical Pearl:**
In clinical practice, a false positive result in the D-xylose test should prompt a thorough evaluation for underlying liver disease, as impaired lactase production is a common cause of a positive D-xylose test result in this context.