When considering the impact of individual test results within the complete set of tests, the MLR indicates that CRP, ESR, ferritin, folic acid, leukocytes, eGFR, reticulocytes and serum iron significantly impact the ability of the GP to diagnose an underlying cause of anaemia (instead of ‘unknown’), regardless whether this diagnosis is correct, as shown in Table 2. Here, CRP is linked to anemia (phenotype).