Hypophosphatemia is an electrolyte disturbance in which there is an abnormally low level of phosphate in the blood. The condition has many causes, but is most commonly seen when malnourished patients (especially chronic alcoholics) are given large amounts of carbohydrates, which create a high phosphorus demand by cells, removing phosphate from the blood (refeeding syndrome).

Because a decrease in phosphate in the blood is sometimes associated with an increase in phosphate in the urine, the terms hypophosphatemia and “phosphaturia” are occasionally used interchangeably; however, this is improper since there exist many causes of hypophosphatemia besides overexcretion and phosphaturia, and in fact the most common causes of hypophosphatemia are not associated with phosphaturia.

Standard intravenous preparations of potassium phosphate are available and are routinely used in malnurished patients and alcoholics. Oral supplementation also is useful where no intravenous treatment is available. Historically one of the first demonstrations of this was in concentration camp victims who died soon after being re-fed: it was observed that those given milk (high in phosphate) had a higher survival rate than those who did not get milk.