Nephrology is the medical specialty devoted to diseases of the kidneys. In addition to filtering blood and removing waste products created by muscular activity, the kidneys also keep levels of potassium, phosphorus, calcium and other substances within a healthy range. As renal failure declines, the kidneys do this job less effectively. As this occurs, patients meet with nephrologists to manage this problem.
Monitoring
Kidney patients are routinely monitored by their nephrologists. This monitoring may include calculating renal function, tracking blood pressure, and measuring serum levels of creatinine, urea, red blood cells and urine protein. Nephrologists also routinely measure serum levels of phosphorus, calcium and potassium. In some instances, the nephrologist may provide nutritional counseling or refer the patient to a renal dietitian. Since dietary advice is linked to this monitoring, kidney patients should never change their diets without consulting their nephrologists.
Warning
Many unscrupulous marketers prey upon desperate kidney patients, offering treatments backed by pseudo-scientific claims or promises of being "safe" "natural," or "cleansing." Since the wait for a kidney can be five years or more in some areas, patients often feel compelled to explore such options. These "treatments" can be very dangerous because they do not take the patient's unique nutritional needs into consideration. Regardless how nutritional such products sound, consult your nephrologist before trying them.
Protein
In the early stages of renal disease, some patients have high levels of urine protein. Proteins are very large molecules and the tiny filters in the kidneys, also called glomeruli, are very delicate structures. When proteins pass through the glomeruli, they can become damaged. For this reason, some doctors may suggest protein restriction. Protein restriction is never suggested in the absence of a total evaluation. For example, protein restriction is inappropriate for children, who need protein to grow. Likewise, it is never recommended for dialysis patients who often need extra protein because dialysis removes certain amino acids from the blood. Similarly, patients approaching transplant or dialysis need all the protein they can get. Never embark on a low protein diet without consulting your nephrologist.
Potassium
The different concentrations of potassium on either side of the neuron, or nerve cell, make nerve transmission possible. Normal nerve transmission is essential to keeping the heart beating regularly so healthy kidneys keep potassium concentrations within a very narrow range by filtering out excess potassium. The kidneys of patients with advanced kidney disease are less able to do this, so potassium levels often begin to creep up. If this happens, your nephrologist or renal dietitian may counsel you about potassium restriction and how much potassium is safe for you to consume.
Phosphorus
Kidneys also keep serum levels of phosphorus in a healthy range. The kidneys of patients with advanced disease are less able to remove phosphorus, so serum phosphorus levels often become elevated. The excess phosphorus leads to lower calcium levels in the bones, weakening bones and making them brittle. To prevent this from happening, nephrologists recommend phosphorus restriction and often prescribe phosphorus binders that keep phosphorus levels within a healthy range.
References
- National Institutes of Diabetes and Digestive and Kidney Disease; Chronic Kidney Disease-Mineral and Bone Disorder; Feb. 2009
- National Institutes of Diabetes and Digestive and Kidney Disease; Treatment Methods for Kidney Failure: Hemodialysis; Dec. 2006
- National Kidney Foundation: Phosphorus and Your CKD Diet
- National Kidney Foundation: Potassium and Your CKD Diet
