Analytic clinical laboratory precision. State of the art for selected enzymes.

Results of precision estimates are reported for selected enzyme analytes. Laboratories that participated in regional quality control programs supplied data to a centralized data processing service (College of American Pathologists Computer Center). These data, representing several regional groups which used different commercial sources of control serum, were statistically analyzed by regression of coefficient of variation (CV) upon concentration of analyte using a modified polynomial regression technic. Tolerance limits for long-term within-laboratory precision were developed from this data. Estimated CVs were extracted at selected analyte concentrations, and tolerance limits for CVs at these concentrations were developed. In addition, selected individual methods within the larger groups were individually examined to evaluate effect of control material matrix upon clinical estimates of enzyme precision. Differences in selected method groups are discussed.

Cystic adventitial disease.

Cystic adventitial disease represents an unusual cause of peripheral vascular insufficiency. A mucinous cyst in the outer media or adventitia progressively compromises the arterial lumen. The therapy can be either aspiration of the cyst or resection with graft interposition. We present two cases involving the popliteal artery that were treated by resection. This lesion may be recognized by its angiographic appearance associated with a lack of generalized atherosclerotic disease.

Preliminary observations on the Quality Assurance Service Therapeutic Drug Monitoring Program.

In 1979, the College of American Pathologists introduced a Therapeutic Drug Monitoring Interregional Daily Quality Control Program. Each participant uses lyophilized, reconstituted control material at normal and elevated levels. Nine drugs are provided at each level. These include phenobarbital, primidone, carbamazepine, ethosuximide, phenytoin, theophylline, digoxin, quinidine, and gentamicin. These specimens are run daily in the individual participating laboratory as part of a routine quality control program. Results are submitted for data processing to the CAP Computer Center. This report presents preliminary data and observations from the Program.