The best guide to determine the progress and severity of renal bone disease is the amount of parathyroid hormone (PTH) in the blood.

PTH, a substance produced in the parathyroid glands, helps control levels of calcium in the blood. In kidney failure, blood calcium levels can become low. When this happens the body compensates by producing more PTH. This causes calcium to drain from the bones into the blood and the bones become weaker.

Raised PTH levels are common in kidney failure and aggravate renal bone disease.

PTH levels can be measured by a simple blood test. Changes in PTH levels in the blood can tell us what will happen to the bones. The lower the PTH, the better.

Since renal bone disease can be present before dialysis is needed, doctors will often measure a patient's blood PTH before dialysis is required.

Once a patient has started dialysis, PTH is usually measured every six months. If the patient has a high blood PTH, treatment is begun to prevent the renal bone disease from worsening.