THE EXTRACTION AND ESTIMATION OF HUMAN URINARY PARATHYROID HORMONE

Abstract

SUMMARY A benzoic acid adsorption method for the extraction of parathyroid hormone (PTH) from 48 hr samples of human urine has been devised. Evidence for the hormonal nature of the extracts is given and recovery experiments with the benzoic acid method are reported. Biological testing was based on the renal action of PTH (i.e. increase in urinary inorganic phosphate). Human urinary extracts were assayed against 'Parathormone' by means of a urinary phosphate assay in mice [Davies, Gordon & Mussett, 1955]. The activity of the benzoic acid extracts in liberating calcium from bone was not tested, since it was expected that the amount present in normal 48 hr samples of human urine would be too small to be detected by existing assays for the calcium-mobilizing effect of PTH. The urinary excretion of PTH was compared in a small series of normal and pathological cases. Assuming 'Parathormone' to contain 100 'phosphate units' (P.u.) per ml., mean values for human urinary excretion of PTH as P.u./24 hr, were: Normal (5 subjects): 60·4 (range 47–72). Confirmed hyperparathyroidism, with concurrent uraemia (4 subjects): 121·2 (range 103–146). Hypoparathyroidism (4 subjects): amount too small to be assayed (assay insensitive to 24 hr urine extracts containing <30 P.u.).