hyponatremia in Cystic fibrosis??

[Northerncardinal]

Is there hyponatremia in Cystic fibrosis?? can anyone explain the mechanism please?

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[Charleybacktoreality]

due increased excretion of Nacl in sweat glands?

 

[Charleybacktoreality]

also Na is trapped inside the cells and can't be secreted in other organs like GI,lungs

 

[Ven0m]

Several mutations in the CFTR gene can occur, and different mutations cause different defects in the CFTR protein, sometimes causing a milder or more severe disease. These protein defects are also targets for drugs which can sometimes restore their function. ΔF508-CFTR, which occurs in >90% of patients in the U.S., creates a protein that does not fold normally and is not appropriately transported to the cell membrane, resulting in its degradation. Other mutations result in proteins that are too short (truncated) because production is ended prematurely. Other mutations produce proteins that do not use energy normally, do not allow chloride, iodide, and thiocyanate to cross the membrane appropriately,[44] and degrade at a faster rate than normal. Mutations may also lead to fewer copies of the CFTR protein being produced.[20]

The protein created by this gene is anchored to the outer membrane of cells in the sweat glands, lungs, pancreas, and all other remaining exocrine glands in the body. The protein spans this membrane and acts as a channel connecting the inner part of the cell (cytoplasm) to the surrounding fluid. This channel is primarily responsible for controlling the movement of halogens from inside to outside of the cell; however, in the sweat ducts, it facilitates the movement of chloride from the sweat duct into the cytoplasm. When the CFTR protein does not resorb ions in sweat ducts, chloride and thiocyanate[45] released from sweat glands are trapped inside the ducts and pumped to the skin. Additionally hypothiocyanite, OSCN, cannot be produced by the immune defense system.[46][47] Because chloride is negatively charged, this modifies the electrical potential inside and outside the cell that normally causes cations to cross into the cell. Sodium is the most common cation in the extracellular space. The excess chloride within sweat ducts prevents sodium resorption by epithelial sodium channels and the combination of sodium and chloride creates the salt, which is lost in high amounts in the sweat of individuals with CF. This lost salt forms the basis for the sweat test.[20]

https://en.wikipedia.org/wiki/Cystic_fibrosis#Pathophysiology

 

[navigator]

I'm a little confused bc I thought hyponatremia is a manifestation of having too much water rather than too little sodium... so why would losing Na+ (in CF patients) cause hyponatremia instead of hypovolemia?

Sorry to necromance but I just got a UW question (ID 1939) about this exact topic (hyponatremia in CF) wrong. And now I'm second guessing what I already knew about Na+/volume status changes haha