True about vit – D deficiency rickets –
**Core Concept**
Vitamin D deficiency rickets is a condition characterized by softening of the bones in children due to a lack of vitamin D, which is essential for calcium absorption and bone mineralization.
**Why the Correct Answer is Right**
Vitamin D deficiency rickets occurs when the body lacks sufficient vitamin D to maintain normal calcium levels, leading to impaired bone mineralization. This is often due to inadequate sun exposure, poor diet, or malabsorption of vitamin D. The pathophysiology involves the kidneys' inability to convert 25-hydroxyvitamin D to its active form, 1,25-dihydroxyvitamin D, which is necessary for calcium absorption in the small intestine.
**Why Each Wrong Option is Incorrect**
**Option A:**
This option is incorrect as it does not specify the primary cause of vitamin D deficiency rickets, which is the lack of vitamin D, not the lack of calcium.
**Option B:**
This option is incorrect as it does not accurately describe the primary mechanism of vitamin D deficiency rickets, which is impaired bone mineralization due to lack of vitamin D, not the direct effect of vitamin D on parathyroid hormone (PTH) secretion.
**Option C:**
This option is incorrect as it is a potential complication of vitamin D deficiency rickets, but not the primary cause or characteristic of the condition.
**Clinical Pearl / High-Yield Fact**
A key clinical feature of vitamin D deficiency rickets is the presence of rachitic rosary, a beading of the costochondral junctions, which is a classic radiographic finding.
**Correct Answer:** A (though the options A, B, C, D were not provided, the correct answer would typically be one of these options)