Shaul G. Massry Division of Nephrology, The University of Southern California, School of Medicine Los Angeles, California In the last two decades evidence has accumulated indicating that parathyroid hormone may exert a multitude of effects on many cells and a variety of organs beyond its classical targets: the kidney and the bone. These efforts have been spearheaded by nephrologists. The interest of this group of clinicians-scientists stems from the fact that patients with renal failure have secondary hyperparathyroidism and markedly elevated blood levels of PTH (1,2). If this hormone does...