Biochemical Changes Following Parathyroidectomy

Abstract

This chapter discusses the biochemical changes following parathyroidectomy. The hypophosphatemic effect of parathyroid hormone is attributable to reduced tubular reabsorption of phosphorus. It is seen that the initial PTH levels are all high, and the operation is associated with a transient rise in plasma PTH followed by a rapid fall representing a half-time of about an hour. Thereafter, the fall in plasma PTH is much slower and in one case actually gives way to a raise in PTH concentrations. The fall in plasma calcium lag behind the fall in plasma PTH by several hours, suggesting that the biological half-life of the PTH effect on the target organ is longer than that of the circulating hormone. It is noted, however, that although plasma PTH levels still appear to be high at 24 h, there is at this time no-evidence of increased parathyroid hormone activity as judged by the tubular reabsorption of either calcium or phosphate. The possibility must therefore be considered that this immuno-assayable material still circulating at 24 h after operation represented a biologically inactive fragment of the hormone.