What Is Hypophosphatemia?

Hypophosphatemia is a condition in which phosphate levels are too low. Phosphate is an electrolyte, a type of mineral that is found in your blood, urine, tissues, and body fluids.

Electrolytes help balance the water and pH (a measure of acidity and alkalinity) in your body, move nutrients into your cells, and clear wastes out. They have a role in keeping your heart, brain, muscles, and nerves working well. You also need phosphate to keep bones and teeth strong.

When phosphate levels in the blood are less than 2.5 milligrams per deciliter (mg/dL), it can cause serious health problems for your lungs, heart, and muscles.

Hypophosphatemia Symptoms

Hypophosphatemia may not show any symptoms in the early stages. In severe cases, you may notice the following:

• Muscle weakness
• Bone pain or rickets (softening of the bones)
• Seizures
• Mental confusion
• Rhabdomyolysis (muscle begins to break down and release harmful proteins in the blood, which may damage the kidneys)
  

If not treated, severe hypophosphatemia can lead to coma or death.

Causes

Hypophosphatemia can be caused by health conditions, medical treatments, or malnutrition. They include.

• Alcohol use disorder
• Medicines: Such as insulin, intravenous iron, chemotherapy drugs, or long-term diuretic (water pill) use, and antacids containing aluminum and magnesium (especially in people with chronic kidney disease)
• Vitamin D deficiency
• Starvation or malabsorption (difficulty absorbing nutrients from food)
• Severe burns
• Electrolyte disorders when magnesium or potassium levels are too low
• During recovery from diabetic ketoacidosis, both as a symptom of the disorder and from insulin treatment for it
• Hyperparathyroidism, which develops when your parathyroid makes too much hormone

Some genetic conditions can also cause low phosphorus levels:

• Fanconi syndrome: A rare genetic condition that leads to bone marrow failure
• Familial hypophosphatemia: A group of rare inherited disorders that includes X-linked hypophosphatasia
  

Diagnosis

Hypophosphatemia is diagnosed by a blood test to check phosphate levels. You have the condition if levels are 2.5 mg/dL or less. If the cause is unclear, your doctor may test vitamin D levels, liver function, and kidney function.

Treatment

If blood tests show that you have hypophosphatemia, you’ll be treated for the disorder causing it and given phosphate-replacement treatment.

Treating the Cause

Addressing the cause of hypophosphatemia may include vitamin D supplementation, refeeding (in the case of starvation or malnourishment), or treatment of specific health conditions.

For instance, diabetic ketoacidosis happens when your body doesn't have enough insulin to move sugar from your blood vessels into your cells for energy. Instead, your kidneys “spill” the sugar from your blood into your urine, dragging phosphate with it.

Acid levels in your blood are also increased with diabetic ketoacidosis, and this forces some of the phosphate from your blood vessels into the surrounding tissues, which lower blood phosphate levels. Finally, treatment with insulin can move phosphate from your blood vessels into the surrounding tissues, which further lowers blood phosphate levels.

Oral Phosphate

Oral treatment of hypophosphatemia involves taking sodium phosphate or potassium phosphate tablets. Your healthcare professional will decide how much to give you, but it could be as much as three doses per day to equal 1 gram of phosphate daily.

However, diarrhea is a common side effect of these medications. If that happens, you may be instructed to drink 1 liter of low-fat or skim milk a day, which also contain 1 gram of phosphate.

Intravenous Phosphate

Some people are unable to be helped by oral phosphate treatment. Their hypophosphatemia may be so severe that they need a treatment that will work faster. Or they have a medical condition that makes oral treatment unsafe. In those cases, phosphate will be given intravenously (directly into your vein using a needle or tube).

Intravenous phosphate may be prescribed due to the following:

• When blood phosphate levels are less than 1 mg/dL
• When nervous system symptoms, extreme muscle weakness, or hemolysis (breakdown of red blood cells) are present

Prognosis

Outcomes depend on what caused the hypophosphatemia. If the cause is chemotherapy drugs, keeping phosphate at or above normal levels will help. Treating the condition that caused hypophosphatemia, such as diabetic ketoacidosis, will also help get levels back to normal.

Summary

Hypophosphatemia is a condition in which phosphate levels decrease below 2.5 mg/dL. When phosphate levels get too low, your heart, lungs, and brain can be damaged. Medical conditions, medications, injury, and lifestyle can cause hypophosphatemia. These include severe burns, diabetic ketoacidosis, alcohol use disorder, and chemotherapy drugs.

Outcomes depend on what caused hypophosphatemia. But getting phosphate levels back to normal is the main goal. This includes oral treatment with tablets or intravenous treatment.

A Word From Verywell

Early stages of hypophosphatemia may not show any symptoms. You may find out you have it during routine blood work. Or perhaps you have diabetes and develop hypophosphatemia during treatment for diabetic ketoacidosis. In either case, phosphate-replacement treatment can return phosphate levels to normal.

You can lessen your chances of getting hypophosphatemia. If you have a chronic condition, such as diabetes or kidney disease, follow the treatment plan provided by your healthcare professional. If you are diagnosed with alcohol use disorder, seek help. After treatment, if you experience any symptoms of hypophosphatemia, contact your healthcare provider right away.