Question
A 2-year-old child presents with bow legs, normal calcium, and high PTH. The probable diagnosis is?
| A. |
Scurvy
|
| B. |
Rickets
|
| C. |
Hyperparathyroidism
|
| D. |
Diabetes Insipidus
|
Show Answer
|
Correct Answer � B
Explanation
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|
Rickets is a disorder of defective mineralization of growing bones due to vitamin D deficiency, resulting in:
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Growth plate widening
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Bowing of weight-bearing long bones
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Elevation of alkaline phosphatase
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Elevated PTH due to secondary hyperparathyroidism
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Normal or low calcium, low phosphate
Lab correlation:
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Normal calcium: due to compensatory increase in PTH
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Elevated PTH: reflects secondary hyperparathyroidism due to hypovitaminosis D
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Supports the diagnosis of nutritional rickets
Why Other Options Are Incorrect:
A. Scurvy
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Caused by vitamin C deficiency, leading to defective collagen synthesis.
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Presents with bleeding gums, irritability, pseudoparalysis, and subperiosteal hemorrhages — not bow legs.
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PTH levels are not elevated in scurvy.
C. Hyperparathyroidism
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Usually seen in adults; primary hyperparathyroidism causes high calcium, not normal calcium.
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It doesn’t cause bowing of legs in children.
D. Diabetes Insipidus
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Involves ADH deficiency or resistance, leading to polyuria, polydipsia, and dehydration.
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No relevance to bone deformity or elevated PTH.
