Phosphate is an electrolyte that is present throughout the body and is an important part of bone matrix, along with calcium. The body typically does not excrete appreciable amounts of phosphate into the urine because of a myriad of functions that phosphate plays in the body. Sometimes, however, phosphate may appear in the urine, resulting in a condition known as phosphaturia.
Hyperparathyroidism
One cause of phosphaturia is elevated levels of parathyroid hormone in the blood, which is also known as hyperparathyroidism, MedlinePlus explains. The parathyroid is a gland that is located near the thyroid gland in the neck. Parathyroid hormone helps regulate calcium and phosphate levels in the blood. When the levels of parathyroid hormone increase, the kidneys excrete more phosphate and take in more calcium. Primary hyperparathyroidism is the result of the parathyroid glands becoming enlarged and secreting too much parathyroid hormone. Secondary hyperparathyroidism is caused by abnormally low levels of calcium in the blood, which signals to the parathyroid glands to secrete more parathyroid hormone. Both forms of hyperparathyroidism can lead to phosphate appearing in the urine.
Diuretic Use
Diuretics, also known as water pills, help increase urine output by increasing the amount of electrolytes that remain in the urine. The kidneys will increase the volume of urine in order to dilute out these extra electrolytes. Phosphate, which is an electrolyte, can appear in higher quantities in the urine with repeated use of diuretics, according to the Merck Manual.
Fanconi Syndrome
The kidneys are responsible for maintaining proper electrolyte balance in the urine. Fanconi syndrome is a condition which causes the kidneys to fail, the University of Maryland Medical Center explains. Fanconi syndrome can occur during childhood due to genetic defects, but it can also occur later in life as a result of kidney damage. Patients suffering from Fanconi syndrome will have the appearance of a number of substances in the urine, including phosphates.
Hypophosphatemic Rickets
Hypophosphatemic rickets is a rare genetic disease of the kidneys, the Merck Manual notes. This condition, which manifests early in life, is the result of a genetic defect that causes the kidneys to secrete large amounts of phosphate into the urine. Phosphate is necessary for proper bone growth, and as a result of the phosphate depletion, affected children can develop bone deformities.
