Bone Disease in Dialysis Patients

Bone disease in dialysis patients is often associated with elevated parathyroid hormone, called "Secondary Hyperparathyroidism". This condition can be seen in many patients in the stage of chronic renal failure, i.e., in the pre-dialysis period.

• Low Calcium: Decreased blood calcium levels

• Vitamin D Deficiency: Decreased vitamin D in the body

• High Phosphorus: Increased blood phosphorus levels

• Vitamin D is formed in the body with the help of an enzyme released from the kidneys to turn into its active form. In the case of kidney failure, this enzyme cannot be produced sufficiently, which causes a decrease in vitamin D levels in the blood.

• High phosphorus levels directly stimulate the parathyroid gland, increasing parathyroid hormone production. Low calcium levels, on the other hand, reduce the pressure of parathyroid on calcium, increasing parathyroid hormone production.

• As a result, persistently low blood calcium levels, decreased vitamin D levels, and high phosphorus levels lead to enlargement of the parathyroid gland and "Secondary Hyperparathyroidism". This can cause damage to the bones.

This disease is caused by high blood levels of aluminum and has toxic effects on the bones. High levels of aluminum are usually caused by dialysate water or long-term use of aluminum-containing phosphorus binders. However, due to modern treatment standards and the use of aluminum-free drugs, this disease is less common today.

Mild or moderate bone disease in dialysis patients is often asymptomatic. However, symptoms may include:

Hyperparathyroidism-Related Bone Disease:

• Bone pain

• Joint discomfort

• Itching

Acute arthritis, known as "metastatic calcification," can cause pain and limited mobility due to the deposition of calcium-phosphorus complexes around the joint.

• Aluminum-Related Bone Disease:

• Severe bone pain and limited mobility

• Fractures in ribs and other bones

Anemia and central nervous system effects (stuttering, speech disorders, muscle twitching, convulsions, personality changes, dementia, etc.) due to aluminum poisoning

• Hyperparathyroidism-Related Bone Disease:

• Alkaline Phosphatase: Bone-derived Alkaline Phosphatase levels are usually high and can sometimes be up to 10 times normal. It should be ensured that other organ-derived enzymes are normal.

• Calcium: Usually normal or slightly low; advanced hypercalcemia may be observed.

• Phosphorus: May be high before dialysis; high phosphorus levels alone do not indicate serious bone disease.

• Parathyroidism: Usually high; values ​​higher than 250-300 pg/ml indicate hyperparathyroidism.

• Aluminum-Related Bone Disease: Alkaline Phosphatase and Parathormone: In long-term aluminum toxicity, these values ​​may be normal or slightly high.

• Calcium: Usually normal.

• Blood Aluminum Level: In dialysis patients, it usually varies between 10-60 µg/lt. Values ​​above 30 µg/lt may indicate aluminum overload.

It is done to prevent bone disease in dialysis patients, control hyperparathyroidism levels and reduce bone aluminum accumulation:

A. Hyperparathyroidism:

• Calcium Supplementation: Dialysis patients usually have low calcium intake, so calcium carbonate and calcium acetate are used. It is recommended that calcium intake be done between meals or at night.

• Control of Serum Phosphorus Level: High phosphorus levels can cause metastatic calcification by increasing the calcium-phosphorus ratio. Phosphorus levels should generally be kept between 4-5.5 mg/dlt. Phosphorus removal during dialysis is important but limited. Phosphorus intake should be controlled.

• Phosphorus Binding Drugs: Calcium-containing phosphorus binders (Phos-ex, Calcium carbonate), Sevelamer (Renagel), and aluminum-free options should be preferred. Aluminum-containing drugs should generally be avoided.

• Vitamin D Treatment: Vitamin D can improve bone health by increasing calcium absorption from the intestine and inhibiting parathyroid hormone release. The goal of vitamin D therapy is to maintain parathyroid hormone levels at 150-200 pg/ml.

B. Parathyroidectomy: If parathyroid hormone levels do not decrease despite high-dose vitamin D therapy, surgical removal of the large parathyroid gland may be considered. This may prevent dangerous levels of calcium-phosphorus multiplication and metastatic calcification.