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Hyperphosphatemia

Written by Dr.Mary

What is Hyperphosphatemia?

Hyperphosphatemia is derived from the element, phosphorus. Hyper means there is a significant increase or marked elevation. The role of phosphorus in our body is for bone mineralization, cellular structure, genetic coding, and for energy metabolism. It is considered hyperphosphatemia when the levels are greater than 5 mg/dL in adults and 7 mg/dL in children or adolescents when the normal range is 2.5 to 4.5 mg/dL. The elevation of phosphorus is proportional to the decrease in serum calcium levels.


People prone to such condition are those with end-stage renal disease. In the United States, about 250,000 people are affected of hyperphosphatemia. Those with chronic increased phosphate levels have a higher mortality rate, compared to those who have normal phosphate levels despite having renal failure. There is no clinical significance of sex-related phosphate levels. Naturally, infants, children and postmenopausal women have high levels of phosphorus. But those with renal problems are reported to have abnormal levels of phosphorus.

In order to diagnose such condition, here are some of the laboratory tests:

Blood test

Serum phosphate level in the normal range should be 2.5 to 4.5 mg/dL and in children for 3 to 6 mg/dL. BUN and creatinine levels are altered. Serum magnesium level may be low.

Hyperphosphatemia Symptoms

Increased amounts of phosphate in the system can have a serious effect on the person’s nervous and cardiovascular system:

  • Central Nervous system effect: altered mental status, delirium, obtundation, coma, convulsions and seizures, muscle cramping or tetany, neuromuscular hyperexcitability and paresthesia.
  • Cardiovascular system effect: hypotension, heart failure, and prolongation of the QT interval (ECG).
  • Eyes: Cataracts.

Hyperphosphatemia cases do not necessarily need hospitalization, not unless the condition was identified while in admission. But this condition needs to be constantly assessed when complications arise such as hypocalcemic tetany or massive extraosseous deposition of calcium phosphate crystals.

Hyperphosphatemia Causes

Phosphorus is an essential element of the cellular system. Phosphorus plays a balance between the intracellular and extracellular compartments and to our tissues and bones. Hyperphosphatemia is commonly caused by the alteration of our renal system causing the decrease of renal excretion of phosphate. Marked elevation of phosphorus is due to these factors:

  • Renal insufficiency – acute or chronic. Renal insufficiency or renal failure is one of the common causes of hyperphosphatemia. The kidneys role is to adequately filter out the toxins and waste products from our blood. Since the normal functioning of the renal system is not attained, it filters out the excess phosphate of our body.
  • Cellular injury – trauma, burns, shock are some of the causes of hyperphosphatemia.
  • Poison – excessive intake of biphosphonate and vitamin D intoxication can cause this condition.
  • Acidosis – diabetic and alcoholic acidosis are one of the root causes of the marked elevation of phosphate in the system.
  • Hypoparathyroidism – The low levels of the parathyroid hormone cause this condition. Normally, the PTH acts as an inhibitor for renal reabsorption. When PTH is not enough in the body, there is more reabsorption of phosphate thus resulting to hyperphosphatemia.
  • Tumor lysis syndrome – This condition is often caused by cytotoxic therapy. The mechanism of this condition is the rapid cell turnover causing increase release of phosphate and other elements such as potassium, purines, and cell proteins.

Those who are at risk for hyperphosphatemia are the following patients who have these conditions:

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  • Renal disease – Those who may have past or recent sessions of hemodialysis.
  • Cancer – Bone tumor is a risk factor of the condition. Chemotherapy treatment can also alter the levels of phosphorus.
  • Medications – Taking oral potassium phosphate, antacid use and biphosphonate therapy makes a person at risk for this condition.

Hyperphosphatemia Treatment

Emergent care is vital once symptoms affecting the nervous system and cardiovascular system have become prominent. Treat hypocalcemia for this can provide additional problems. Calcium replacement is provided to patients. Hemodialysis or peritoneal dialysis is indicated in severe cases. When a person acquired this condition because of toxicity, gastric lavage is indicated for treatment. Phosphate binders are given to prevent phosphate reabsorption. Dietary restriction of food rich in phosphate must be followed. Education from a licensed dietician is appropriate for food suggestions that contain high or low phosphate contents.

Here are the specific drugs for hyperphosphatemia:

Diuretics

This can lower phosphate serum levels by enabling renal excretion of the excess phosphate. Furosemide (Lasix) is commonly prescribed.

Phosphate binders

These bind to phosphate contained in food, as a result, it limits intestinal absorption. Aluminum hydroxide (Amphogel), calcium carbonate (Caltrate), calcium acetate (Calphron), magnesium hydroxide (Milk of Magnesia), sevelamer hydrochloride (Renagel) and lanthahum carbonate (Fosrenol).

The prognosis of this condition is good when the condition is in its acute phase for treatment can be successful. Chronic hyperphosphatemia can have a mixed prognosis. Complications may arise from chronic hyperphosphatemia. One should subject oneself for treatment when the condition has been diagnosed. We need not to wait for the condition to be at its worse before we subject ourselves for treatment.

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