Invited Review PTH(1–84)/PTH(7–84): a balance of power

doi:10.1152/ajprenal.00336.2005.—This review considers many new basic and clinical aspects of parathyroid hormone (PTH). We focus especially on the identification of PTH fragments and how they may relate to renal failure, diagnosis, and treatment of secondary hyperparathyroidism and renal osteodystrophy. The biosynthesis and metabolism of PTH, measurement of circulating forms of PTH, the effects of PTH on receptor activation and turnover, the relationship between PTH levels and bone turnover in renal failure in humans, and the involvement of PTH in experimental models of renal failure are discussed. Despite these develop-ments in understanding the etiology of renal failure and the availability of new assays for bioactive PTH, no adequate surrogate for bone biopsy and quantitative bone histomorphometry has been developed. peptide fragments; hormone resistance; receptor downregulation; immunometric assay; renal osteodystrophy RECENT YEARS HAVE WITNESSED remarkable progress in under-standing parathyroid gland physiology in general and in furthe