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Low numbers of red blood cells may indicate anemia, which has many causes including:
Blood loss
Iron deficiency
Deficiences of vitamin B12 or folic acid
Bone marrow failure (for example, from radiation, toxin, fibrosis, tumor)
Erythropoietin deficiency (secondary to kidney disease)
Hemolysis (RBC destruction)
Leukemia
Multiple myeloma
Over hydration
Low numbers of white blood cells (leukopenia) may indicate:
Bone marrow failure (for example, due to granuloma (granular tumor), tumor, or fibrosis)
Presence of cytotoxic substance
Collagen-vascular diseases (such as lupus erythematosus)
Disease of the liver or spleen
Radiation exposure
High numbers of white blood cells (leukocytosis) may indicate:
Infectious diseases
Inflammatory disease (such as rheumatoid arthritis or allergy)
Leukemia
Severe emotional or physical stress
Tissue damage (for example, burns)
A high hematocrit may indicate:
Dehydration
Burns
Diarrhea
Eclampsia
Erythrocytosis
Polycythemia vera
Shock
Review Date 6/3/2025
Updated by: Ramin Fathi, MD, FAAD, Director, Phoenix Surgical Dermatology Group, Phoenix, AZ. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
