SALT intake advice in cystic fibrosis is under review after ETI improved conservation and blood pressure.
Why Salt-Wasting in Cystic Fibrosis Matters
People with cystic fibrosis can experience chronic sodium and chloride losses, leaving them vulnerable to dehydration and electrolyte and acid base disturbances. Clinical guidance has therefore encouraged increased salt intake. As highly effective CFTR modulator therapy becomes more common, clinicians need evidence on how these treatments reshape volume and electrolyte homeostasis and what that means for day-to-day counseling.
ETI Treatment Shifts Volume and Electrolyte Balance
In this study, investigators followed 50 people with cystic fibrosis as they initiated elexacaftor/tezacaftor/ivacaftor (ETI). They assessed blood pressure, electrolyte and acid base measures, aldosterone levels, and renal handling of sodium and water using an oral sodium bicarbonate and volume loading test that quantified diuretic and natriuretic responses.
After starting ETI, participants showed higher blood pressure and higher plasma sodium. ETI was also associated with a stronger diuretic response to the sodium bicarbonate and volume loading challenge, consistent with improved handling of an acute sodium and volume load. Alongside these changes, heart rate and aldosterone levels decreased, venous total CO2 decreased, and fewer participants had low plasma sodium. The authors suggest that rescue of renal CFTR function may contribute to these effects.
Salt-Wasting in Cystic Fibrosis: Implications for Counseling and Risk
Overall, the findings indicate that ETI improves sodium chloride and fluid conservation, effectively correcting salt-wasting in cystic fibrosis. The authors conclude that additional salt repletion may be unnecessary for ETI treated people with cystic fibrosis, a point that could influence future dietary guidance.
At the same time, the rise in blood pressure highlights a potential tradeoff. If correction of chronic salt loss shifts individuals toward higher effective circulating volume, clinicians may need to pay closer attention to cardiovascular risk after ETI initiation. The study team recommends that future guidelines weigh this potential increase in cardiovascular disease risk when advising on sodium intake and follow up monitoring in ETI treated cystic fibrosis.
Reference: Berg P et al. Elexacaftor/tezacaftor/ivacaftor corrects salt-wasting in cystic fibrosis. Journal of Cystic Fibrosis. 2026;25(1):32-37.
