Clinical and biochemical correlates of growth associated with short-term administration of methionyl growth hormone.

Twenty newly diagnosed growth hormone-deficient children (19 males) were randomized to receive methionyl growth hormone (0.3 mg/kg/week) in subcutaneous doses divided daily (n = 12) or 3 times per week (TIW). With the initial dose and at 4-6 weeks after beginning therapy, procollagen type III propeptide (PIIIP) concentrations were determined. Growth velocities were calculated before and at 1, 3, and 6 months after beginning the therapy. Pretreatment growth velocities were 3.66 +/- (SD) 1.45 and 3.79 +/- 0.55 cm/year for the daily and TIW groups, respectively. At 1, 3, and 6 months mean growth velocities increased to 17.2, 10.2, and 9.5 cm/year for the daily group and 9.8, 6.8, and 7.6 cm/year for the TIW group, with differences between groups significant (p < 0.05) at 1 and 3 months. PIIIP concentrations increased significantly (p < 0.05) over 1 month in both groups, from 11.3 to 18.8 ng/ml and from 10.0 to 12.0 ng/ml in the daily and TIW groups, respectively. In addition PIIIP concentrations were significantly higher (p < 0.05) in the daily group at 1 month. A significant correlation was found between PIIIP concentrations at 1 month and the growth velocity at 1 (r = 0.47), 3 (r = 0.60), and 6 (r = 0.67) months. Pretreatment growth velocity was weakly correlated with posttreatment growth velocity at both 1 (r = -0.45) and 3 (r = -0.42) months. We conclude that (1) growth hormone is more effective when administered daily, (2) pretreatment growth velocity and PIIIP plasma concentration at 1 month correlate with 1 month growth velocity, and (3) PIIIP at 1 month provides a good evaluation of 6 months' response to methionyl growth hormone therapy.