Relationship between urinary hydroxyproline and growth.

Beginning with the report of Ziff, Kibrick, Dresner, and Gribetz (2), evidence accumulated in recent years has indicated that urinary hydroxyproline excretion reflects collagen metabolism, since collagen is the only protein in the body that contains hydroxyproline in significant amounts (3). Ziff and co-workers, observing that the excretion of this amino acid in peptide form was greater in children than in adults, suggested that the level of urinary hydroxyproline might be related to the size of the metabolically active, soluble collagen pool available for breakdown. The results of a number of investigations (4-7) have supported this suggestion. In the present paper, further investigation of the relationship between growth and hydroxyproline excretion has been carried out in man. Urinary hydroxyproline has been determined in patients with normal, arrested, and accelerated growth, and in cases in which arrested growth has been stimulated by hormonal therapy. The data obtained indicate that the level of excretion of hydroxyproline shows a good correlation with rate of growth under all circumstances studied and, therefore, offers a useful and readily measured index of this phenomenon.