thick ascending limb - barter syndrome

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60

What major transporter is present on the luminal membrane of the TAL?

Na⁺-K⁺-2Cl⁻ cotransporter (NKCC2).

61

What channel recycles K⁺ back into the TAL lumen?

ROMK.

62

What is the major basolateral chloride channel associated with TAL?

ClC-Kb.

63

Why does the TAL promote paracellular Ca²⁺ and Mg²⁺ reabsorption?

K⁺ recycling creates a lumen-positive electrical potential, driving paracellular cation reabsorption.

64

What syndrome results from defects in TAL salt reabsorption?

Bartter syndrome.

65

What is the inheritance pattern of Bartter syndrome?

Usually autosomal recessive.

66

What are the classic biochemical findings in Bartter syndrome?

Hypokalemia + metabolic alkalosis + secondary RAAS activation.

67

What happens to urinary calcium in Bartter syndrome?

Hypercalciuria.

68

What renal complication can result from hypercalciuria in Bartter syndrome?

Nephrolithiasis/nephrocalcinosis.

69

What happens to Mg²⁺ in some Bartter types?

Hypomagnesemia, particularly noted with type V.

70

Which Bartter types typically present in children with severe disease?

Types I and II.

71

Which Bartter type is considered the classical adult form?

Type III.

72

Which Bartter type is associated with sensorineural hearing loss?

Type IV.

73

Which Bartter type involves a calcium-sensing receptor defect?

Type V.

74

What is the key treatment principle for classic Bartter syndrome?

NSAID such as indomethacin → ↓prostaglandins → ↓secondary RAAS drive.