Your kidneys receive a large supply of blood per hour. They play important roles in regulating the composition of blood, such as the levels of water and electrolytes such as phosphate. Kidney damage interferes with kidney functioning and can lead to electrolyte imbalances. Phosphate levels can get out of balance, leading to further problems that require treatment. The diagnosis and management of kidney disease, electrolyte imbalances and other related problems should be managed by a healthcare professional.
Kidney Regulation of Phosphate
Blood flows into the kidneys, and its liquid component flows into special tubes called nephrons, which make urine. The nephrons regulate the composition of the urine and blood by regulating how much phosphorus is excreted via the urine. Parathyroid hormone signals the kidneys to dispose of phosphate, take up calcium into the blood and synthesize vitamin D. Vitamin D raises phosphate and calcium levels.
Effects and Mechanism of Kidney Disease on Phosphate
In kidney disease, nephron activity decreases or stops altogether, and the kidneys no longer respond to hormones. As a result the protein channels that normally transfer phosphate ions from the blood into the urine do not work. Phosphate levels rise, while calcium levels decline. The kidneys also do not synthesize vitamin D, causing further problems for calcium and phosphate levels.
Consequences
Abnormally high phosphorus and low calcium levels in the blood can cause nerve and muscle problems. In addition, this mineral imbalance stimulates the parathyroid glands to release parathyroid hormone in an attempt to raise calcium and lower phosphate. However, this has no effect on the kidneys. Instead, the parathyroid hormone stimulates the bone to release calcium and phosphorus. This causes bone to lose mass and weaken. Bone disease caused by kidney disease and subsequent phosphate, calcium and parathyroid hormone imbalances is called renal osteodystrophy.
Diagnosis and Treatment
Diagnosing kidney disease involves measuring blood and urine components and changes in urine output. Establishing the cause involves further studies. High phosphate levels are treated with medicines that bind phosphate in the GI tract, such as calcium acetate and sevelamer.
References
- "Physiology"; Linda S. Costanzo; 4th Ed. 2008
- "Robbins and Cotran Pathologic Basis of Disease"; Vinay Kumar et al.; 8th Ed. 2009
- "Harrison's Principles of Internal Medicine"; Anthony S. Fauci et al.; 17th Ed. 2008
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