The kidneys make a molecule called bicarbonate that is like the sodium bicarbonate that you can take to neutralize stomach acids. This bicarbonate that is made by the kidneys is used by your body to neutralize body acids that are made during metabolism by your cells.

When the kidneys begin to fail they lose their ability to generate enough of this bicarbonate leading to a chronic metabolic acidosis.

This chronic metabolic acidosis can begin long before a patient is on dialysis and can lead to deleterious effects on protein balance leading to a negative nitrogen balance and poor nutrition and increased breakdown of body proteins. Synthesis of albumin is also decreased. This causes loss of lean body mass and muscle weakness.

Metabolic acidosis is also a factor in the development of renal bone disease, as bone acts as a buffer for excess acid, with loss of mineral resulting from the increase in acid. This leads to a weakening of the bones.

The chronic metabolic acidosis also leads to decreased production of certain hormones like insulin like growth factor-1.

Metabolic acidosis can also cause abnormalities in calcium balance and lead to kidney stones and also lead to low phosphorous levels in the blood stream. Abnormal calcium balance and phosphate depletion combine to induce a metabolic bone disease that exhibits features of both osteoporosis and osteomalacia

If you are not yet on dialysis, your metabolic acidosis will be treated by taking sodium bicarbonate tablets. If you are on dialysis your metabolic acidosis is treated by your dialysis treatment.

Metabolic acidosis is an important cause of weak bones. For more information please go back to the Kidney education page and click on "bone".