Renal Osteodystrophy

Renal osteodystrophy is a disease that frequently accompanies the chronic kidney failure. It can be translated as bone disorder related to kidney pathologies.


For understanding the renal osteodystrophy, it is important to know some basic information about the relation between calcium and phosphates. Calcium is present in blood, but the greatest amount of calcium is stored in the bones. The blood level of calcium is increased due to function of a hormone called PTH (parathyroid hormone), which increases bone resorption and release of calcium molecules into the blood. The product of blood concentrations of calcium and phosphates is constant, i.e. an increase in blood calcium level decreases the concentration of phosphate and vice versa.


Chronic kidney failure decreases the ability of renal tissue to excrete phosphates and the phosphates accumulate in the blood. Elevated concentration of blood phosphates leads to a decrease in blood calcium (hypocalcemia). The parathyroid glands react by increased production of PTH hormone and the excessive amount of parathyroid hormone tries to increase the level of calcium. This condition may be described as the secondary hyperparathyroidism. The level of calcium in the blood rises, but the cost is a massive bone decalcification.


In addition to other typical symptoms of chronic renal failure, the patients suffer from bone problems due to decrease of their structural integrity and strength. The bones are painful and weak. They deform and fractures occur more frequently.


The condition can be anticipated in patients with chronic renal failure. The blood tests may show elevated level of phosphates and lower or even normal level of calcium (due to compensatory effect of the parathyroid hormone). The serum concentration of PTH hormone is elevated due to its excessive production by parathyroid glands.


It is primarily necessary to treat the chronic kidney failure, which is responsible for the condition. The patients should receive diet with reduced intake of phosphates and vitamin D is regularly administered in order to increase the level of calcium in the blood and to suppress the production of PTH. As a support therapy, the doctors may prescribe special medications that reduce the amount of phosphates in the body.


Jiri Stefanek, MD  Author of texts: Jiri Stefanek, MD
 Sources: basic text sources