Serum macro creatine kinase type 2 in asphyxiated newborn infants

The presence of macro creatine kinase type 2 (MCK2) activity was noted in the serum of seven out of 32 newborn infants with perinatal asphyxia or birth trauma. MCK2 isoenzyme, when present, represented 15-35% of the total creatine kinase (CK) activity. The clinical and biochemical features of the seven MCK2-positive and 25 MCK2-negative newborns were compared. The infants with MCK2 activity were all males and clinically appeared to be more severely injured, requiring longer hospitalization. Total CK activity was similar in the two groups and CK-MB and CK-BB isoenzyme fractions were present in a similar proportion of infants in both groups. Two infants in each group had long-term neurological disorders. Although the presence of MCK2 has been noted in adult patients with end-stage metastatic solid tumors, the presence of this isoenzyme has not previously been reported in newborn infants.