Intake of extra salt by baby’s not harmful?

Question

Dear,

Normally spoken one says that salt is not good for baby’s, it is not good for the kidneys. Now a baby with CF does get extra salt capsules. Are you sure that there is no harm in this? Or do we just have to choose between 2 bad things?
Thanks for your reaction.

Answer

Mother milk and also classical adapted baby milks have a very low salt content (for somebody who knows about chemistry: less than 1 mmol or 1mEq/100ml) This amount just suffices for a baby who does not have extra salt losses. But a baby with CF does have extra salt needs because he loses salt via the sweat. If a baby with CF gets regular milk and no salt supplement, he runs a big chance to get into a salt deficit. And there is 2 ways a baby with CF can suffer from this. Both complications are well known.

Most frequently the salt deficit will come on very gradually and therefore there is an imbalance in the ionic composition in the blood. As the shortness of mainly chloride increases other also negative loaded particles in the blood will increase, for instance bicarbonate. Because bicarbonate is raised potassium decreases and when potassium is very low the kidney can no longer function properly. The baby will have excessive urination because he cannot concentrate his urine. The baby will then lose weight, have a poor appetite and it will get progressively worse. Usually the baby will arrive in the hospital. Sometimes this condition is even the first sign of the disease cystic fibrosis. This presentation is called pseudo-Bartter syndrome, because there is also a disease called Bartter syndrome, that has nothing to do with cystic fibrosis, where the baby urinates a lot because it has a kidney problem.

The second way in which salt deficit can occur in CF is on very hot days or after strenuous exercise. In that case, there is acutely loss of salt via the sweat. And indeed the sweat test was discovered on a very hot summer. During that summer it was obvious that many children with severe dehydration arrived at the hospital. What was so special about these children? Well they were suffering from cystic fibrosis. It was discovered that they lose a lot of salt in their sweat and the sweat test was born.

Of course we want to prevent these salt deficits. That is why every baby with CF, as long as he drinks only milk, gets salt supplements. As soon as he takes other food substances and bread, this extra salt intake is no longer needed. But on hot days and with intensive exercise, all people with CF should take extra salt.

When these guidelines are followed we can prevent admission to hospital. We hope you now understand why salt supplements are very important for a baby with CF.

Best regards,

Prof. K. De Boeck

01.09.2011