Final answer:
Secondary hyperparathyroidism in chronic renal failure leads to increased production of parathyroid hormone, which attempts to raise blood calcium levels while also causing the kidneys to excrete more phosphate. This can progress to tertiary hyperparathyroidism with serious complications such as hypercalcemia, renal osteodystrophy, and vascular calcification.
Step-by-step explanation:
Secondary hyperparathyroidism (HPT) is often associated with chronic renal failure (CRF), a condition where the kidneys lose their filtering capabilities over time. In CRF, the kidneys are less effective in excreting phosphate, leading to increased serum phosphate levels. This, in turn, causes a decrease in serum calcium levels. The parathyroid glands attempt to compensate by producing more parathyroid hormone (PTH), which works to raise blood calcium levels by reducing the loss of calcium through the kidneys. Simultaneously, PTH increases the loss of phosphate through the kidneys. This overcompensation can eventually lead to tertiary hyperparathyroidism, characterized by hypercalcemia, renal osteodystrophy, and vascular calcification, all of which can contribute to further impairment of cardiac function.