NPPB and COVID-19: Systematically comparing all observed tests and test combinations, Fig. 4 reveals certain high-volume single laboratory tests (e.g. creatinine, lymphocyte, RBC) that had a high number of abnormal test results observed during the COVID-19 pandemic but little change in test abnormality rates, and certain less common combinations of tests (e.g. those including monocyte, D-dimer, fibrinogen, ESRR, BNP, and IL2/IL4/IL6) that had a low number of abnormal test results observed during the COVID-19 pandemic but a high percentage increase in test abnormality rates.