Phosphorus Imbalance

What is Phosphorus Imbalance ?

Phosphorus, the primary intracellular anion, is critical for normal cellular functioning. It's mainly found in inorganic combination with calcium in teeth and bones.

Phosphorus has a variety of important functions, such as formation of energy-storing substances (adenosine triphosphate) and support to bones and teeth. It also plays a role in utilization of B vitamins, acid-base homeostasis, nerve and muscle activity, cell division, and metabolism of carbohydrates, proteins, and fats.

Renal tubular reabsorption of phosphate is inversely regulated by calcium levels-an increase in phosphorus causes a decrease in calcium. An imbalance causes hypophosphatemia or hyperphosphatemia.

Causes of Phosphorus Imbalance

Rarely, mild hypophosphatemia results from decreased dietary intake. When combined with overuse of phosphate-binding antacids, hypophosphatemia may become severe. Decreased absorption due to such conditions as vitamin D deficiency, malabsorption syndromes, or diarrhea may also cause this condition.

More commonly, hypophosphatemia stems from respiratory alkalosis. (Prolonged, intense hyperventilation can cause severe hypophosphatemia.) Also, increased urinary excretion associated with such conditions as hyperparathyroidism, aldosteronism, renal wbular defects, and administration of mineralocorticoids, glucocorticoids, or diuretics may lead to hypophosphatemia.

Other important causes include the use of total parenteral nutrition with inadequate phosphate content, diabetic ketoacidosis, chronic alcoholism, and alcohol withdrawal, which may lead to severe hypophosphatemia.

Hyperphosphatemia most commonly results from renal failure with decreased renal phosphorus excretion. It may also stem from overuse of laxatives with phosphates or phosphate enemas, excessive administration of phosphate supplements, and vitamin D excess with increased GI absorption.

Signs & Symptoms of Phosphorus Imbalance

Mineral imbalance, especially calcium and magnesium; impaired bone and teeth formation; kidney function; heart muscle contraction problems.

Some chronic conditions can lead to low levels of phosphorus in the body and symptoms of this type of deficiency include:

• debility,
• mental confusion,
• weakness,
• loss of appetite,
• irritability,
• speech problems,
• anemia,
• lowered resistance to infection, and
• osteomalacia.

Diagnostic Tests

Serum phosphorus values less than 1.7 mEq/L or 2.5 mg/dl confirm hypophosphatemia; results that are more than 2.6 mEq/L or 4.5 mg/dl confirm hyperphosphatemia.

Urine phosphorus values greater than 1.3 g/24 hours support hypophosphatemia; values under O.9g/24 hours support hyperphosphatemia.

Treatment

The goal of treatment is to correct the underlying cause of phosphorus imbalance. In the meantime, management of hypophosphatemia consists of phosphorus replacement, with a high phosphorus diet and oral administration of phosphate salt tablets or capsules. Severe hypophosphatemia requires I.V.infusion of potassium phosphate, I.V. supplements are also required when the GI tract can't be used to administer supplements.

Hyperphosphatemia is commonly treated with aluminum, magnesium, or calcium gels or antacids, which bind with phosphorus in the intestine and increase its elimination. Reduced phosphorus intake may be used in conjunction with these phosphorus-binding antacids. Severe hyperphosphatemia may require peritoneal dialysis or hemodialysis to lower the serum phosphorus level.

Prevention Tips

Phosphorus imbalances caused by hormonal disorders or other genetically determined conditions cannot be prevented. Hypophosphatemia resulting from poor dietary intake can be prevented by eating foods rich in phosphates, and hypophosphatemia caused by overuse of diuretics or antacids can be prevented by strictly following instructions concerning proper dosages, as can hyperphosphatemia due to excessive use of enemas or laxative. Finally, patients on dialysis or who are being fed intravenously should be monitored closely to prevent phosphorus imbalances.