Clinical value of plasma creatine kinase and uric acid levels during first week of life

Abstract

Levels of creatine kinase and uric acid in cord blood were variable but similar to those in maternal blood. During the first 24 hours of life there was a rise in the concentration of both substances, particularly of creatine kinase, to reach levels well above those normally found in later childhood. Thereafter there was a steady fall to stable levels around the fifth day. The causes of these obvious changes in concentration are not known.

Uric acid levels during the first 24 hours were higher after a longer labour. Creatine kinase levels were lower, and uric acid levels higher in low birthweight babies. The plasma creatine kinase originated from non-cardiac muscle.

Plasma creatine kinase and uric acid levels may help in the early diagnosis of rare specific disorders such as muscular dystrophy and the Lesch-Nyhan syndrome, but do not help in the diagnosis of other neurological disorders at this time of life, and give no indication of the child's prognosis, despite their occasional help in adult patients. Even with the specific syndromes, however, interpretation must be guarded. It is not known whether the high creatine kinase levels associated with Duchenne muscular dystrophy would be lost in the upper limits of the normal range for the first few days of life or whether they would be higher still. In the Lesch-Nyhan syndrome uric acid levels are well above the normal range defined in this investigation.