Question:medium
In Bartter syndrome, the genetic defect is located in the:
In Bartter syndrome, the genetic defect is located in the:
Show Hint
Bartter mimics a loop diuretic, so the defect sits where loop diuretics act - the TAL.
Updated On: Jun 23, 2026
- Defect in PCT
- Defect in DCT
- Defect in thick ascending limb of loop of Henle
- None
Show Solution
The Correct Option is C
Solution and Explanation
Step 1: Localise the transporter that fails. Bartter syndrome behaves like a patient chronically on a loop diuretic, and loop diuretics act on the thick ascending limb.
Step 2: The targeted machinery in the TAL is the $Na\text{-}K\text{-}2Cl$ cotransporter plus the ROMK ($K^+$) and ClC-Kb ($Cl^-$) channels; an inherited defect in any of them blocks salt reabsorption at this segment.
Step 3: Downstream this gives hypokalaemic metabolic alkalosis, urinary salt and calcium loss, high renin/aldosterone but low or normal blood pressure.
Step 4: Contrast with Gitelman syndrome, which is the DCT (thiazide-type NCC) defect with hypocalciuria - that excludes option b, while the PCT is uninvolved. The answer is the thick ascending limb.
\[\boxed{\text{Thick ascending limb of loop of Henle}}\]
Step 2: The targeted machinery in the TAL is the $Na\text{-}K\text{-}2Cl$ cotransporter plus the ROMK ($K^+$) and ClC-Kb ($Cl^-$) channels; an inherited defect in any of them blocks salt reabsorption at this segment.
Step 3: Downstream this gives hypokalaemic metabolic alkalosis, urinary salt and calcium loss, high renin/aldosterone but low or normal blood pressure.
Step 4: Contrast with Gitelman syndrome, which is the DCT (thiazide-type NCC) defect with hypocalciuria - that excludes option b, while the PCT is uninvolved. The answer is the thick ascending limb.
\[\boxed{\text{Thick ascending limb of loop of Henle}}\]
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