EDITORIAL NOTES Measurement of Parathyroid Hor-

mone THE DEVELOPMENT OF radioimmunoassay tech-niques for measuring plasma concentration of peptide hormone has made possible many important conceptual advances in clinical en-docrinology. Adaptation of these methods to parathyroid hormone (PTH) has proved diffi-cult, but recent progress in several laboratories provides hope that the assay of PTH will be clinically useful in the foreseeable future (1-3). The following problems have delayed prog-ress: [1] it has been difficult to produce antisera with sufficiently high affinity for PTH to make them suitable for assay work; [2] bovine an