Evaluation of creatine kinase level during long-term tocolysis

This study was performed to evaluate serum creatine kinase (CK) levels during tocolytic therapy.

A retrospective study was performed in 27 patients who were treated with intravenous tocolytic agents for more than one week. The first-line tocolytic agent was ritodrine hydrochloride, followed by concomitant magnesium sulfate (MgSO4). The serum CK level was measured on admission and every week thereafter. The patients were divided into the normal CK (group 1) and abnormal CK (> 150 IU/L) (group 2) groups.

Seventeen patients received both ritodrine hydrochloride and MgSO4. The CK levels in all patients rose significantly from 58.4 +/- 30.8 IU/L on admission to 116.0 +/- 68.7 IU/L on day 7 (p = 0.002). Abnormal elevation of CK occurred in 7 (25.9%) of the 27 patients. Significant differences were found between groups 1 and 2 in the total doses of ritodrine and MgSO4 (p = 0.046 and p = 0.0028, respectively). All patients in group 2 received ritodrine in combination with MgSO4 (p = 0.018).

When tocolytic therapy continued for more than 1 week, nearly one-fourth of patients showed an increase in CK level above the normal range.