Phosphate, calcium and lipid metabolism

Ca and Pi interact with lipid metabolism in several different ways. The enzymes of lipolysis and lipogenesis are sensitive to Ca. Ca and Pi concentrations affect insulin secretion and insulin action. Raising intestinal Ca lowers serum cholesterol and triglycerides presumably by sequestration of cholesterol and bile acids. Administration of vitamin D or increased sensitivity to vitamin D raise serum cholesterol levels. PTH acts primarily by activating adipose tissue lipase. Increased FFA delivery to the liver should increase hepatic lipoprotein synthesis. Experimental data in secondary hyperparathyroidism of renal insufficiency are consistent with this notion. Clinical observations in primary or renal secondary hyperparathyroidism, however, are not explicable by this simple schema.