OBJECTIVE: The purpose of this investigation was to evaluate the effectiveness of short-term administration of recombinant biosynthetic IGF-I on patients with an hereditary inability to generate this hormone.

DESIGN AND PATIENTS: Ten patients with Laron type dwarfism (LTD) (4 males, six females) aged 3 1/2 to 37 3/4 years were submitted to seven daily s.c. injections of recombinant IGF-I in doses of 120 or 150 micrograms/kg/day.

MEASUREMENTS: Blood samples were drawn before, after three and seven injections, and one week after stopping the trial.

RESULTS: The main biochemical and hormonal changes registered were (mean +/- SD): a marked rise in serum type III procollagen (PIIINP) from 4.2 +/- 0.9 to 7.3 +/- 2 micrograms/l (P less than 0.0003) and decrease in the following blood components: plasma hGH from 32.51 +/- 43.77 to 4.02 +/- 2.48 mU/l (P less than 0.001), serum cholesterol from 5.9 +/- 1 to 5.7 +/- 0.8 mmol/l (P less than 0.04), serum SGOT from 28.9 +/- 11.6 to 15.5 +/- 7.6 U/l (P less than 0.01) and serum LDH from 286 +/- 88 to 222 +/- 37 U/l (P less than 0.0005). The response of plasma insulin was variable, decreasing in seven of ten and increasing in three. Some of these effects were transitory, and were found after 3 days therapy but afterwards decreased (insulin, cholesterol and liver tests), others persisted throughout the whole treatment period (hGH, PIINP).

CONCLUSIONS: IGF-I mimics the biochemical and hormonal changes described after administration of hGH. The administration of IGF-I in patients with Laron type dwarfism is devoid of side-effects and warrants assessment in long-term studies.