Vitamin A (retinol) toxicity — clinical features: Which set best describes recognized symptoms of hypervitaminosis A in humans?

Introduction / Context:
Vitamin A (retinoids) is essential for vision and epithelial integrity, but excess (hypervitaminosis A) produces characteristic toxicity. Recognizing its symptom cluster is important for clinicians and exam candidates.

Given Data / Assumptions:

• Retinol and retinoic acid act via nuclear receptors affecting gene expression.
• Toxicity can be acute or chronic depending on dose and duration.
• Typical systemic symptoms include constitutional, gastrointestinal, musculoskeletal, and neurologic signs.

Concept / Approach:
Integrate known clinical manifestations: nausea and vomiting (GI), lethargy/weakness (CNS/constitutional), and bone changes such as pain and fragility due to altered osteoclast/osteoblast activity.

Step-by-Step Solution:
Identify GI symptoms: hypervitaminosis A commonly leads to nausea.Identify constitutional symptoms: fatigue, weakness, headaches are frequent.Identify skeletal symptoms: chronic excess can cause bone pain and fragility (increased fracture risk).As all are recognized, choose “All of these.”

Verification / Alternative check:
Standard pharmacology and nutrition references list these as hallmark signs alongside others (alopecia, dry skin, hepatotoxicity, intracranial hypertension).

Why Other Options Are Wrong:
Each single symptom captures only part of the syndrome, not the full recognized triad.

Common Pitfalls:
Confusing beta-carotene excess (carotenemia with skin yellowing but minimal toxicity) with retinol toxicity.

Final Answer:
All of these.