Nutrition and Metabolism — MCQs

Q: A child presents with alopecia, hyperpigmentation, hypogonadism, and a rash on the genital area and mouth. What deficiency is most likely responsible?

Zinc deficiency. The clinical presentation described is a classic manifestation of **Zinc deficiency**. Zinc is a vital trace element required for over 300 metalloenzymes (e.g., Carbonic anhydrase, Alkaline phosphatase, RNA polymerase). ### **Why Zinc Deficiency is Correct** The triad of **alopecia, periorificial dermatitis** (rash around the mouth, eyes, and genitals), and **diarrhea** is pathognomonic for severe zinc deficiency. Zinc is essential for DNA synthesis and cell division; hence, rapidly dividing tissues like skin and the immune system are affected first. In children, it also leads to **hypogonadism** (delayed sexual maturation), growth retardation, and impaired wound healing. ### **Why Other Options are Incorrect** * **Iron deficiency:** Primarily presents with microcytic hypochromic anemia, pica, and koilonychia (spoon-shaped nails), but not periorificial rashes or hypogonadism. * **Calcium deficiency:** Presents with neuromuscular irritability (tetany, Chvostek/Trousseau signs), rickets in children, or osteomalacia in adults. * **Copper deficiency:** Leads to Menkes kinky hair syndrome (brittle, "steely" hair), microcytic anemia (refractory to iron), and neurological degeneration, but not the specific periorificial rash seen here. ### **NEET-PG High-Yield Pearls** * **Acrodermatitis Enteropathica:** An autosomal recessive disorder caused by a mutation in the *SLC39A4* gene, leading to impaired intestinal zinc absorption. It presents identically to the question above. * **Enzyme Marker:** Serum **Alkaline Phosphatase (ALP)** levels often decrease in zinc deficiency because ALP is a zinc-dependent enzyme. * **Other features:** Zinc deficiency is also associated with **dysgeusia** (distorted taste) and **impaired night vision** (as it helps mobilize Vitamin A from the liver).

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Macronutrients and Energy Requirements

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Protein Quality and Nitrogen Balance

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Essential Amino Acids and Proteins

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Essential Fatty Acids and Lipids

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Dietary Fiber and Complex Carbohydrates

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Glycemic Index and Glycemic Load

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Micronutrients: Vitamins and Minerals

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Trace Elements and Metabolism

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Dietary Antioxidants

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Functional Foods and Nutraceuticals

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Dietary Guidelines and Recommendations

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