All are features of Barters syndrome, EXCEPT:-
**Core Concept**
Bartter syndrome is a rare genetic disorder characterized by impaired salt reabsorption in the thick ascending limb of the loop of Henle in the kidneys. This leads to hypokalemic alkalosis, normal to low blood pressure, and various other electrolyte imbalances.
**Why the Correct Answer is Right**
Bartter syndrome is caused by mutations in genes encoding proteins involved in salt reabsorption, such as the Na-K-2Cl cotransporter (NKCC2) in the thick ascending limb. The syndrome is characterized by salt wasting, hypokalemia, metabolic alkalosis, and normal to low blood pressure. Patients often have a high urinary calcium excretion, leading to nephrocalcinosis and kidney stones.
**Why Each Wrong Option is Incorrect**
**Option A:** Hyperkalemia is incorrect because Bartter syndrome is typically associated with hypokalemia, not hyperkalemia.
**Option B:** Nephrogenic diabetes insipidus is incorrect because Bartter syndrome is not directly associated with this condition.
**Option C:** Hypercalcemia is incorrect because Bartter syndrome is often associated with hypocalcemia, not hypercalcemia.
**Clinical Pearl / High-Yield Fact**
The key feature of Bartter syndrome is the inability to reabsorb salt in the thick ascending limb of the loop of Henle, leading to a cascade of electrolyte imbalances.
**Correct Answer: A. Hyperkalemia.**