Kidney failure and your bones - Renal Osteodystrophy

Many people think that your kidneys just produce urine for waste disposal. But the kidneys also help keep your bones in good health and strong. Bones are quite complex things, and carry out several important functions in the body. Their internal structure (below) is quite complex, with a honeycombe structure for lightness, and channels through which blood vessels pass.

Structure of bone

The kidneys help keep your bones healthy because they also produce calcitriol, better known as vitamin D. The job of calcitriol is to stimulate the absorption of calcium and phosphate in your blood and in your bones. The primary tissue of bones, called osseous tissue, is composed mostly of calcium phosphate, with collagen to form a natural composite material. Together they combine strength and hardness with some elasticity (flexibility). The amount of calcium in your blood has to be kept under control for your body to function properly. Calcium is found in dairy products, green vegetables and eggs.

Your kidneys would normally monitor and adjust the levels of calcium and phosphate ions. But kidney failure may cause a drop in the production of calcitriol, which in turn can lead to higher levels of these important ions in your blood, and eventually result in renal bone disease, or to give it its full medical name, Renal Osteodystrophy.

Renal Osteodystrophy can exist with little or no symptoms, but the following symptons may occur:

Often Renal Osteodystrophy is diagnosed when a kidney failure patient reaches end stage renal failure, and decreased calcium and calcitriol levels are detected in blood tests, along with increased phosphate levels. Patients may then be x-rayed to check for bone problems.

The treatment involves taking calcium and vitamin D supplements, a restriction in dietary phosphates, and phosphate binders. And, as you may have guessed, dialysis.

The parathyroid glands are tiny glands, 1mm across, but not related to the better known thyroid glands, they just happen to be found behind it in your neck. They secrete a hormone (chemical messenger) called PTH, short for parathyroid hormone (not the world's most imaginative name), which controls the calcium level in your blood by drawing calcium from the bones when needed, as well as increasing the amount absorbed from food. The glands produce more of the hormone when the calcium levels drop. Too much calcium, less hormone is produced. But if PTH is produced in large amounts in an attempt to sort out low calcium levels in your blood, the glands can get out of control, leading to continual high levels of calcium. An operation to remove then is then required.

Other Diseases

Renal failure patients are also susceptible to several other diseases.
Adynamic bone disease, Osteoporosis, Osteoarthritis, Amyloid, Infection, Gout, to name a few.