[Serum hydroxyproline parameter of collagen metabolism (author's transl)]

The serum hydroxyproline level enables a clinical assessment to be made of bone metabolism. A clinical-chemical method, which is described in detail, was applied in 50 control persons as well as in 76 patients with diseases of bones and/or joints. This method, which is a modification of the standard ion-exchange method of Goverde and Veenkamp for the determination of free hydroxyproline in serum, is readily applicable to mass routine laboratory usage and may be repeated ad libitum, thereby facilitating control follow-up of therapeutic response. The mean value of serum free hydroxyproline in the normal control group was 11.9 mu mol/1 (range: 6.86 to 16 mu mol/1), i.e. 1.56 mg/1 (range: 0.9 to 21 mg/1). The upper limit of normal values was calculated to be 15.5 mu mol/1 (2.0 mg/1), allowing a clear-cut differentiation from pathologically raised levels above this value.