[Linearity and blank value in the serum creatine phophokinase MB-fraction determination by means of the inhibition test].

The inhibition test shows elevated creatine kinase MB (CK-MB) activity if the test volume is reduced. Hence, sera with considerably increased serum protein values may produce negative CK-MB results. What is involved here is an apparent blank phenomenon dependent on the serum proteins. This effect is not derived from the Inh-CK-M antibody but is directly connected with the CK-reagents, since analogous relationships are also shown with the conventional CK-method. In order to produce reliable inhibition test results, a reflectant blank versus test-volume and serum protein level must be taken into account.