evaluation of plasma creatine phosphokinase (cpk) level following a single injection of methotrexate as a predicator of treatment success in ectopic pregnancy.

objective: to evaluate the plasma creatine phosphokinase (cpk) level after a single injection of methotrexate (mtx) as a predictor of treatment success in ectopic pregnancy (ep). materials and methods: in this prospective study, seventy nine women older than 18 years treated with methotrexate for ectopic pregnancy were evaluated for cpk and β-subunit of human chorionic gonadotropin (βhcg) levels, while they received intramuscular mtx at a dose of 50 mg/m2. the day of injection was considered as day 1 (d1). cpk level on d1 was compared between the group 1(as treatment success group), treated by a single mtx injection, and the group 2, treated by two or three mtx injections or by surgery. results: the success rate of mtx treatment was 58 (73.3%). the mean of cpk was higher in treatment success group (group1) than failure group (group 2) (71.98 ± 15.711 vs. 64.43 ± 15.898), but the difference was not significant (p=0.06). the mean of βhcg was significantly lower in treatment success group (group 1) than failure group (group 2) (1187.52±631.45 vs. 1663.87±1096.845; p=0.01). ultrasonographic findings of ep were seen in 63 patients, while the means of βhcg and cpk were higher in these patients than those with normal ultrasonography, but difference was not significant (p=0.37 and p=0.24, respectively). conclusion: the sample was not large enough to indicate a significant difference in the cpk level, which can be considered as an indicator for differentiating between the successful and unsuccessful treatment groups. moreover, the present study did not show any relation between initial β-hcg and cpk serum levels, so our findings indicate that they are not possibly considered as two independent biomarkers in ectopic pregnancy.