PATHOGENESIS OF SECONDARY HYPERPARATHYROIDISM

摘要

Secondary hyperparathyroidism occurs most commonly in association with chronic renal failure (CRF). Secondary hyperparathyroidism is characterized by elevated circulating parathyroid hormone (PTH) concentration with a serum ionized calcium (iCa) concentration either within the reference range, or below. While the serum iCa concentration is normal to low, serum total calcium (tCa) concentration is often elevated in CRF. The incidence of elevated serum tCa increases with the severity of azotemia. In 73cats with CRF, serum tCa was increased in 8% with mild azotemia, 18% with moderate azotemia, and in 32% with severe azotemia. However, serum iCa concentration does not show a strong association with the degree of azotemia. Deleterious effects of hypercalcemia occur only if there are increases in serum iCa concentration, as iCa is the biologically active fraction of calcium.