Normal Potassium Levels in Infants

Potassium is a type of mineral and electrolyte in the body that is maintained by dietary intake. Potassium is important for heart function, muscle contractions and digestion. An infant's body keeps a steady amount of potassium in the bloodstream while excreting excess amounts through the urine. The normal amount of potassium in the bloodstream for an infant is between 3.7 and 5.2 milliequivalents per liter.

Baby (Image: FamVeld/iStock/Getty Images)

Potassium Loss

A baby with potassium levels below normal has a condition called hypokalemia. This occurs among babies who have persistent vomiting or diarrhea. Some babies who are ill and given diuretic medications excrete too much potassium out of the body through the urine, also causing hypokalemia. According to Penn State Medical Center, babies with this condition may have an irregular heartbeat, overall weakness and fatigue, muscle cramps and paralysis.

Dietary Supplements

Infants up to 6 months of age need 500 mg of potassium daily, while babies 6 months to a year need 700 mg daily. St. Jude Children's Research Hospital states that you can increase your baby's potassium intake by feeding her foods such as bananas, melon, sweet potatoes and yogurt.

High Potassium

Babies born with kidney or adrenal problems may have trouble filtering out potassium levels, resulting in high concentrations of potassium in the bloodstream. High potassium may also occur from some diseases, such as Addison's disease or hypoaldosteronism, but is rare among infants. Symptoms include nausea, vomiting, diarrhea, muscle paralysis and irregular heartbeat.


Some babies that have high serum potassium levels may benefit from eating low potassium foods. One half cup of applesauce contains 78 mg of potassium, one egg contains 55 mg and 1 oz. of cheddar cheese contains only 28 mg. Check with your doctor about regulating your baby's potassium intake through his diet.

Premature Infants

Infants that are born before 37 weeks gestation are considered to be premature. These infants may have underdeveloped gastrointestinal systems that cause difficulty with digestion. In situations of extreme prematurity, infants may receive nutrition through IV fluids until they have grown and their gastrointestinal system has developed. Doctors monitor the electrolyte levels of premature babies very closely, including potassium levels. Because a premature baby's body is so fragile, potassium concentrations may be unstable and he may require fluids and medications to bring levels back into balance.

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