Final result of treatment of majority of neoplastic and non‑neoplastic blood disorders depends on their early diagnosis and immediate referral to hematologist. This determines that initial hematological diagnosis has to be carried out on the level of family physician or other doctor, who in the process of diagnosis of other disorder will detect abnormalities that may suggest a blood disorder. Current article concerns the use of a triad of laboratory tests: complete blood count, erythrocyte sedimentation rate, and urine analysis. Borderline values are provided that should prompt referral to a hematologist, and it is explained why these particular values were accepted. Common use of such information should shorten time from initial symptoms of blood disorders to the beginning of therapy.