Final answer:
Secondary hyperparathyroidism in kidney failure is caused by chemical imbalances in the body, primarily involving calcium and phosphate. The compromised kidney function leads to low calcium levels that continuously stimulate the parathyroid gland to produce parathyroid hormone (PTH), leading to bone health issues caused by excessive calcium removal.
Step-by-step explanation:
Secondary hyperparathyroidism in people with kidney failure is caused by the imbalance in chemical regulation in the body. The kidney's inability to fully function can lead to abnormally low calcium and high phosphate blood levels. This causes the parathyroid glands to overcompensate by producing excessive amounts of parathyroid hormone (PTH).
PTH's primary function is to maintain calcium levels in the body - it stimulates osteoclasts to release calcium from bones into the bloodstream, helps in reabsorption of calcium in the kidney, and enhances dietary calcium absorption in the gut by promoting the production of the active form of vitamin D3, calcitriol. However, in kidney failure, the ability of the kidneys to reabsorb calcium and convert calcitriol for calcium absorption from the gut is compromised.
This results in continued low levels of calcium in the blood, which constantly stimulates the parathyroid gland to secrete PTH - leading to secondary hyperparathyroidism. This excessive secretion of PTH influences bone health, as continuous calcium reabsorption from bone to compensate for low calcium levels can decrease bone density and increase the risk of fractures.
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