Elevated serum CK in long abstinent cocaine abusers.

In preparation for an exercise program in cocaine abusers maintained abstinent in a hospital setting (average 98.4 days), we measured resting serum creatine kinase (CK). Surprisingly, many were elevated. Further tests confirmed the observation. We measured 19 long abstinent cocaine abusers, 22 abstinent abusers of other substances, and a later group of 26 long abstinent cocaine abusers. While none of the other substance abusers showed elevated serum CK levels, 53 and 31% of the abstinent cocaine groups did (p = .000082 and .00041, respectively). All CK elevations were muscle derived; repeated sampling demonstrated stability. Cocaine abusers' CK showed a bimodal distribution: the lower bell curve approximated controls and the higher bell curve centered above normal range, at 400 U/L. Demographics did not influence the results. With complementary findings of impaired spatial motor performance, these persistent CK elevations suggest that a large minority of cocaine abusers maintain tendencies to coarse motor control and impulsive movements, and perhaps hyperactivity.