TF and anemia (phenotype): For the other tests with categorical results (i.e. leukocytes, thrombocytes, and transferrin), as well as all tests with numerical results (i.e. creatinine, CRP, eGFR, ESR, folic acid, haemoglobin, LDH, serum iron and vitamin B12) no significant impact of a one unit change in a single test result on the ability of the GP to correctly diagnose the underlying cause of anaemia was found.