Bones, Calcium, Phosphate, and PTH in Kidney Failure - High and Low Calcium Causes, Effects and Treatment
- Low calcium levels in the blood can occur in kidney failure when there is insufficient Vitamin D available, or in people who have already had surgery to remove their parathyroid glands. Low calcium levels may cause no symptoms. Very low levels can cause muscle twitching and spasms, especially in the face and arms. The treatment is to give Vitamin D and calcium supplements in tablet form. An injection of calcium may be used if there is muscle spasm.
- High calcium levels in the blood can be caused by high levels of PTH, or by too much calcium getting into the body because of treatment with calcium and vitamin D tablets. This may cause no symptoms, but high levels of calcium can also cause agitation, gritty eyes, and abdominal pain. The treatment is to stop calcium and vitamin D tablets and, in some cases, to perform surgery to remove the parathyroid glands.
- Low phosphate levels in the blood are not commonly seen in people with kidney failure, but may occur between 2 and 8 weeks after a successful kidney transplant, because the kidney is too leaky and phosphate is passing out through the urine. Usually there are no symptoms, and the treatment is to relax any phosphate restriction in the diet, and to take phosphate tablets.
- High phosphate levels occur in most people on dialysis, and also those with advanced kidney failure. Often there are no symptoms, but high phosphate levels can cause generalised itching, which can be severe. Calcium and phosphate can be deposited in tissues (click here for more details on this - known as cacliphylaxis). The treatment is to optimise dialysis, reduce phosphate in the diet, and to take medication to reduce phosphate absorption. Despite these measures, phosphate is very difficult to control in many people.
- Low PTH may occur after surgery to remove the parathyroid glands, and causes a low calcium level (see low calcium for symptoms and treatment).
- High PTH levels can occur when the parathyroid glands are stimulated. Sometimes PTH can be controlled by using Vitamin D. In some people the parathyroid glands keep producing more and more PTH. This can cause high calcium levels and muscular weakness with aches and pains around the shoulders and hip joints. Eventually, bone disease with shortening of the ends of the fingers and collarbones may occur. The high levels of calcium and phosphate caused by excess PTH can cause chalk to build up in blood vessels and heart valves (click here for more details on this - known as cacliphylaxis). The treatment in severe cases is surgery to remove the parathyroid glands (click here for more details on surgery). Renal Units check PTH regularly in people on dialysis, and try to plan any necessary surgery before serious complications occur.
The National Kidney Federation cannot accept responsibility for information provided. The above is for guidance only. Patients are advised to seek further information from their own doctor.