Electrolytes

The major electrolytes required on a daily basis include sodium, potassium, calcium, magnesium and phosphorus. The amounts of the first two, sodium and potassium, are not specific and are often guided by the clinical needs of the patient. The latter three, calcium, magnesium and phosphorus, have specific recommended dietary allowances (RDAs), and the doses depend on the route of administration (i.e., a catheter into the stomach or intestine, or an intravenous catheter. For delivery into the stomach or intestine of adults, for example, standard amounts equal to the RDAs are often provided in pre-mixed products by the manufacturer and are met when approximately 1500 kcals of the commercial formula are given. For intravenous delivery, specific amounts of these are added by the Pharmacy each day. (www.nutritioncare.org ASPEN and www.espen.org ESPEN links here) Of particular note, calcium and phosphorus have the potential to interact with each other and form an insoluble precipitate. If this precipitate is given by a catheter in the stomach, clogging of the tubing may occur. If the precipitate is given intravenously, clogging of major blood vessels can occur and cause significant harm or even death. Thus, great care is taken in the preparation of intravenous nutrition support to minimize the risk of precipitation between calcium and phosphorus.