Myalgia and elevated creatine kinase activity associated with subcutaneous injections of diluent.

A 16-year-old boy with short stature and mild primary hypothyroidism received subcutaneous injections of either recombinant human growth hormone or placebo in diluent that contained glycerol and m-cresol as a preservative. While he was receiving the study drug, myalgia developed and serum creatine kinase values were elevated. Both resolved when injections were stopped and recurred when injections of diluent alone were given. The myalgia and elevated creatine kinase activity were apparently caused by a component of the diluent.