What is phosphate?
Phosphate is a salt of phosphoric acid. It is found in 85 percent of the bones and teeth, 14 percent in the body’s cells and one percent in the intercellular space. In bone, phosphate binds to calcium and is stored as calcium phosphate (calcium phosphate).
In addition, phosphate is an important energy supplier: energy-rich phosphate compounds (ATP) are present in the cell plamsa, which supply the cells with energy for various metabolic processes through a chemical reaction. Phosphate is also a component of DNA and acts as an acid buffer in the blood and urine.
The so-called parathormone, which is formed in the parathyroid glands, promotes the excretion of phosphate via the kidneys. Growth hormones, thyroid hormones, insulin and cortisone reduce phosphate excretion.
Phosphate metabolism is closely linked to calcium and vitamin D balance. If the blood contains a lot of phosphate, it is simultaneously low in calcium, and vice versa.
If there is too much phosphate in the blood, this is called hyperphosphatemia. This can lead to severe itching, calcification of the heart valves or gout-like joint complaints.
When is the phosphate level determined?
The physician determines a patient’s phosphate level when he suspects a disorder of calcium metabolism. Measurement is also indicated in cases of kidney stones. In addition, the phosphate level is determined as part of check-ups for chronic kidney failure, after thyroid surgery, in cases of severe digestive disorders and alcohol abuse.
Phosphate is determined from blood serum, heparin plasma or urine collected over 24 hours (24-hour urine). The patient should be fasting when the blood is drawn.
Phosphate – normal values
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Normal value |
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Adults |
0.84 – 1.45 mmol/l |
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Children |
Newborns |
1.6 – 3.1 mmol/l |
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until 12 months |
1.56 – 2.8 mmol/l |
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1 – 6 years |
1.3 – 2.0 mmol/l |
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7 – 13 years |
1.0 – 1.7 mmol/l |
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over 13 years |
0.8 – 1.5 mmol/l |
The phosphate normal range in 24-hour collected urine is 16 to 58 mmol/24 hours.
When is the phosphate value elevated?
If there is too much inorganic phosphate in the blood, this is called hyperphosphatemia. The following conditions may be the cause:
- Kidney weakness (renal insufficiency)
- Acromegaly (hormonal disease with overproduction of growth hormone)
- Bone tumors and metastases (see tumor markers)
- Blood cell decay (phosphate release from blood cells)
Blood levels of phosphate are also elevated in vitamin D overdose.
When is the phosphate level decreased?
Blood phosphate levels are decreased in:
- alcohol withdrawal in chronic alcoholism
- lowered blood calcium level
- Vitamin D deficiency
- renal weakness (renal insufficiency)
- artificial nutrition (occasionally)
Elevated phosphate levels in the urine may indicate hyperparathyroidism.
What to do in case of altered phosphate values?
If you have a phosphate deficiency, you should eat foods that contain a lot of phosphate and vitamin D. These include, for example, milk and carbonated beverages. Conversely, in the case of hyperphosphatemia, the intake of phosphate and vitamin D should be reduced. However, the regulation of the phosphate balance must always be carried out under medical supervision, because the concentration of phosphate can also have an influence on heart function, among other things.
