Relation between Urinary Hydroxyproline and Parathyroid Function.

With the exception of small amounts in elastin, all the hydroxyproline (OHPr) in the body is found in collagen. Evidence has been presented that the urinary peptide-bound OHPr reflects the metabolism of collagen (2-5) except when the dietary intake of gelatin or collagen is excessive. Since a major body depot of collagen is the matrix of bone, it might be anticipated that under some conditions the rate of OHPr excretion would furnish an index of the turnover of bone matrix. Parathyroid hormone is known to increase bone resorption (6-11). Thus, changes in parathyroid function might be expected to be associated with changes in OHPr excretion. Recently, Klein and Curtiss (12) reported that urinary OHPr first decreased and then increased in rats given parathyroid extract (PTE). Bates, McGowen, and Talmage noted that PTE increased plasma peptide-bound OHPr in rats (13). An elevated urinary excretion of OHPr has been reported in patients with hyperparathyroidism (14-16). The present studies were carried out to examine further the relationship of parathyroid activity to OHPr excretion.