Step I Bartter's vs Gitelman's

[MudPhud20XX]

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FC says:

"Gitelman syndrome is characterized by a mutation in the Na+/Cl- transporter in the distal convoluted tubule.

• Unlike Bartter syndrome, which usually leads to hypercalciuria, Gitelman syndrome causehypocalciuria, as calcium is spared in the distal convoluted tubule. Patients with Gitelman syndrome also present with hypomagnesemia."

Alright, so I get the hypocalciuria in Gitelman since with defective Na+/Cl- transporter you get steeper Na gradient that facilitates Ca2+ absorption via Na/Ca2+ transporter.

But I can't seem to understand the mechanism for hypercalciuria in Bartter. Can anyone help me out?

Many thanks in advance.

 

[MilkIsGood]

Same mechanism as using loop diuretic. No paracellular transport of Ca, so it stays in urine. This is how I think of it. Dont know if its accurate