[Creatine kinase activity and its isozyme levels in cord blood]

We measured creatine kinase (CK) levels of cord blood and evaluated them in relation to the degree of maturity and distress. The reference value of CK of cord blood in normal neonates was 209 +/- 99 U/l (mean +/- SD) and the percent values of the isoenzymes, CK-MM, CK-MB and CK-BB, were 86.7 +/- 6.2%, 5.1 +/- 2.6%, and 8.1 +/- 5.4%, respectively. There was a positive correlation between the birth weight and CK, CK-MM, CK-MB and CK-BB levels of cord blood. The CK and CK-MM levels of cord blood in the neonates who were prematurely delivered and small-for-date were significantly lower than those in normal controls. The CK and CK-MM levels of cord blood in the neonates with low Apgar scores, 6-4 and 3-0, were 172 +/- 74, 145 +/- 73 and 104 +/- 63, 92 +/- 55 U/l, respectively, which were significantly lower than those in the neonates with the high scores (10-7), 208 +/- 104, 183 +/- 92 U/l. The neonates with distress showed the low CK and CK-MM values, 76 +/- 12 and 61 +/- 8 U/l. The CK and CK-MM levels of cord blood tended to decrease with prolongation of labor, but did not differ from each other among the neonates delivered by different modes. These results suggest that the CK and its isoenzyme levels are good indicators for the degree of maturity of neonates and the severity of neonatal distress.