Phosphate (PO,); Phosphorus (P)

About 85% of the body's phosphorus is found in bones and teeth and is
combined with calcium. The rest of phosphorus is in the soft tissues . Phosphorus
in the blood exists as phosphate, which is necessary for the generation
of bony tissue; the metabolism of glucose, fats, and proteins; and the
storage and transfer of energy. The range of normal for adult phosphate
levels is significantly different than the range of normal for children. The
difference is partially attributed to the increased level of growth hormone
present in children until puberty.
Due to the relationship between calcium and phosphorus, blood phosphate
concentration is closely linked to plasma calcium. Increased phosphorus
levels are accompanied by a decrease in calcium and, conversely,
decreased phosphorus levels are accompanied by an increase in calcium.
Normal Range
Adults
2.7-4.5 mg/dl
Children
4.5-5.5 mg/dl
Blood Chemistry Tests (Part 1)
39
Variations from Normal. Hypopphosphatemia, increased phosphorus
level, is most commonly associated with kidney dysfunction as in renal insufficiency,
severe nephritis, and renal failure . Hypoparathyroidism, increased
growth hormone, vitamin D excess, bone tumors, and Addison's
disease also demonstrate increased phosphate concentrations . In most of
these situations, a decrease in plasma calcium is also present and diagnostically
significant .
Hypophosphatemia, decreased phosphorus level, is associated with
hyperparathyroidism, rickets in childhood, osteomalacia in adults, malabsorption
syndromes, malnutrition, and an excessive amount of insulin
in the body. Hypophosphatemia is accompanied by an increase in plasma
calcium.
Interfering Circumstances. A false increase in phosphate follows the use of
laxatives or enemas. Oral laxatives may increase phosphorus levels as much
as 5 mg/dL within a few hours. Destruction of red blood cells will also
cause hyperphosphatemia.