Phosphate is a mineral that helps develop and repair bones and teeth. It also contributes to nerve function and muscle contractions. The body needs phosphate on the cellular level to provide energy, form cell membranes, and as a component of DNA. Hyperphosphatemia means the amount of serum phosphate or phosphate in the blood is too high. This condition most often occurs as a symptom of other medical issues.

The Body and Phosphate

The small intestine absorbs 60 to 70% of all phosphate taken from foods and amounts to approximately 1000 to 1500 milligrams of phosphate absorbed each day. Vitamin D increases the efficiency of phosphate absorption, but it isn’t essential. The body stores phosphate in bone; this reservoir fluctuates because there is a constant flow in and out.

Direct Symptoms

Hyperphosphatemia often doesn’t present any symptoms, though hypocalcemia, a related issue, can. Hypocalcemia occurs when calcium levels in the body are too low. The two conditions intertwine because abnormal phosphate levels change calcium levels. The most common symptoms of hypocalcemia are muscle cramps, tetany, and perioral numbness or tingling. Tetany is a type of muscle spasm while perioral numbness and tingling related to nerves. Pain in bones and joints or a rash are also possible, but these are less specific symptoms.

Indirect Symptoms

In many cases of hyperphosphatemia, the symptoms are a result of the underlying cause rather than excess phosphate and may affect the kidneys and renal system. Fatigue, shortness of breath, irregular sleep, nausea, vomiting, anorexia, and continuous itchy feelings on the skin are all possible results of impaired kidney function.

Acute Hyperphosphatemia

Acute hyperphosphatemia effects the nervous system. The cause is almost always parenteral phosphate administration, which is the intravenous dispensation of phosphate, which a medical practitioner always carries out. Symptoms include hyperreflexia, muscle spasms, seizures, and a positive Chvostk sign — a reaction to the tapping of a facial nerve. Chvostk sign indicates excessive nerve activity, and hyperreflexia describes exaggerated reflexes.

Causes

The most common cause of hyperphosphatemia is kidney failure or advanced renal insufficiency. An overactive or underactive thyroid gland is fairly common too. Other causes are diabetic ketoacidosis, crushing injuries, certain medications, and severe infection. Rarely, hyperphosphatemia can result from taking too much phosphate orally or using enemas containing phosphate.

Diagnosis

Bloodwork with a comprehensive chemistry profile confirms hyperphosphatemia. The primary values medical professionals examine to make the diagnosis include calcium and phosphate levels in the blood, urea, and creatinine to evaluate kidney function and hormones associated with the thyroid gland. After diagnosis, these values and several others assist in determining the cause of excess phosphate.

Treatment

People without renal insufficiency are given large amounts of saline intravenously, combined with diuretic medication to prompt the kidneys to produce more urine than normal. This process flushes the excess phosphate out of the body, then allowing doctors to address the underlying cause. Thyroid medication corrects imbalances related to the thyroid gland and single event causes like injuries or ingesting too much phosphate do not need further treatment.

Renal Insufficiency

Hyperphosphatemia is more complicated when the cause is kidney failure. There is no cure for kidney failure except a transplant, so treatment is limited to managing symptoms. When kidney failure reaches its final stages, many people choose dialysis. A machine filters the blood for the damaged kidneys, but dialysis is not as efficient as the organs themselves. As such, doctors strictly limit and monitor phosphate intake. A nutritionist or doctor assists in planning meals. Phosphate binders are a routine medication for anyone on dialysis, preventing phosphate absorption in the small intestine.

Foods Containing Phosphate

Identifying phosphate-rich foods is important to limiting intake. A general rule is that protein-rich foods also contain phosphate, but there are exceptions. Meats with high phosphate content include poultry, organ meats, and pork. Sunflower seeds, pumpkin seeds, nuts, whole grain, quinoa, beans, and lentils are also rich in phosphate. Identifying phosphate-rich foods is important to limiting intake. Frozen food, fast food, cola soft drinks, processed meats, and baked goods may be fortified with phosphate.

Prognosis

The prognosis for hyperphosphatemia is excellent in all cases except kidney failure. Elevated phosphate is quick to resolve and it often never happens again after one addresses the cause. Kidney failure is the exception because it is a chronic condition. Phosphate is just one of the many vitamins, minerals, and other substances people with kidney failure have to monitor, and hyperphosphatemia can become a constant condition for people on dialysis.