Declining bone health in chronic kidney disease

As the kidney function declines in Chronic Kidney Disease (CKD), there is phospho-calcic metabolic disorder in the body that impacts the bone health. This is a consequence of loss of nephrons in the kidney causing cascade of excess phosphate absorption at the expense of calcium, with vitamin D deficiency, changes in the calcium-sensing receptors in the parathyroid glands and decreased gastrointestinal absorption of calcium. Without timely initiation of treatment by Best Nephrologist in Lahore this calcium-loss and bone loss can have severe consequences. Read on to know more about CKD and bone health:
What role do hormones play in bone health?

Metabolic disturbance of calcium and other minerals is a common complication of CKD with both skeletal and extra-skeletal consequences. Minerals and hormones play an important role in the formation and calcification of bones. These include:
Calcitriol hormone—the active form of vitamin D that is formed by the kidneys
Parathyroid hormone which controls serum calcium levels

Kidneys play a role in this homeostasis by vitamin D activation, calcium reabsorption and phosphate excretion. In damaged kidneys, as seen in CKD, all the hormones and minerals are impacted.

When these hormones and minerals are out-of-sync, the bones formed are brittle, weakened and malformed. There are higher chances of bone disorders due to low calcium and higher parathyroid hormone in the body.

What is the impact of CKD on bone health?

High phosphate
CKD results in high phosphate, at the expense of calcium, which causes secondary hyperparathyroidism. This disease results in high bone turnover, causing osteitis fibrosa, whereby the calcium for the serum is pulled from the bones, thus weakening the bones. Secondary hyperparathyroidism is seen early on in the course of CKD and causing hyperplasia or growth of the parathyroid gland, producing higher levels of this hormone.

High phosphate levels harden the vessels as well, predisposing the patient to hypertension. Even high parathyroid hormone levels are not good for the heart.
Low serum calcium
Kidneys normally function to prevent calcium loss in the urine. In damaged nephrons, however, there is insufficient reabsorption of calcium, and instead the kidneys reabsorb more phosphate and lose the calcium. The high phosphate triggers production of parathyroid gland, while the calcium is pulled from the bones.
Low serum vitamin D
The last step of vitamin D activation occurs in the kidneys. In chronic kidney disease, this last step is lacking, thereby reducing the amount of vitamin D in the body. Vitamin D primarily functions to increase the absorption of calcium from the food we eat. Without it, there is reduced gastrointestinal absorption of calcium, and this loss is compounded by calcium loss from the kidneys. Consequently, the bones weak further and become brittle. Without treatment, there are bone pains and aches resistant to treatment. There are also increased chances of bone injury in such patients.

How is bone disorder treated in CKD?

In patients with CKD, the goal of therapy is to prevent bone damage by high parathyroid hormone levels, keeping the phosphate levels in check and restoring the proper balance between the hormones.

Medications like paricalcitol and doxercalciferol are like activated form of vitamin D and act to reduce parathyroid hormone levels. In addition to these medications, the healthcare provider prescribes exogenous calcium to strengthen the bones. Other drugs like phosphate binders reduce the phosphate levels in the blood, and are often used in CKD patients. alternatively, increasing the frequency of dialysis also lowers phosphate levels in the body.

There is no single treatment option for improving bone health in CKD. Your healthcare provider like Best Nephrologist in Islamabad will decide on the best treatment right for you.

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