NBME Form 30 Practice Test

The symptoms presented by the 6-year-old boy, specifically the unstable gait and increased fat concentration in the stool, suggest a deficiency in fat-soluble vitamins. Among the options provided, Vitamin E is particularly known for its role as an antioxidant and its importance in neurological function and maintaining the integrity of cell membranes.

In children, a deficiency in Vitamin E can lead to neurological issues such as ataxia and gait disturbances due to its effect on nerve tissue and coordination. Increased fat in the stool, known as steatorrhea, points to malabsorption of dietary fats, which can also suggest an issue with fat-soluble vitamin absorption, further implicating Vitamin E deficiency.

The other vitamins listed—Biotin, Vitamin D, and Vitamin C—do not typically cause these specific symptoms of unstable gait and fat malabsorption at this age. Biotin deficiency is more related to hair loss and skin issues, Vitamin D primarily affects bone health, and Vitamin C deficiency leads to scurvy, which presents with different symptoms such as bleeding gums and fatigue.

Therefore, given the combination of unstable gait and increased fat concentration in stool, Vitamin E deficiency is the most likely explanation for the boy’s symptoms.