Our body relies on the blood to deliver its life-essential oxygen and nutrients to all of the tissues and organs.  The mature blood cells (formed elements) are responsible for delivery of oxygen (RBCs), clotting (platelets), and immunological defence (WBCs).  The watery part of blood, the plasma, carries the nutrients, plasma proteins, electrolytes, and wastes.

The mature blood cells are created in the bone marrow with chemical stimulation of their respective hemopoietic stem cell.  Blood cells/formed elements leave the bone marrow when mature:   RBCs and platelets lack organelles and nuclei and are hence, not cells. Hence, some refer to circulating mature blood cells as formed elements rather than blood cells.

Anemia is the most common disorder in the world. It’s defined as an abnormally low amount of hemoglobin, the iron-containing protein molecule that binds O2 and RBCs.  The cause of anemia can be organized as due to lack of synthesis (i.e. RBCs and/or hemoglobin), loss of whole blood (i.e. bleed), or destruction of RBCs (i.e. RBCs are fragile or something is destroying RBCs). As there is reduced O2 carrying capability, anemia manifests as a global lack of energy production since O2 is preferred to to generate ATP in all cells.  Anemia often manifests as appearing pale, tired, with weakness.  Cardiovascular adaptations such as high heart rate and blood pressure may also be seen.  Diagnosis of anemia is performed with hematological analysis to determine the number of mature RBCs  and iron studies.  Treatment of anemia is to address the underlying cause: whether with nutritional/hormonal supplementation if causes are due to poor synthesis or identifying and stopping the bleed if the cause is due to loss or limiting the RBC destruction if it all possible.

Leukemia is a blood cancer where there is abnormal development and proliferation of a hemopoietic cell line: either myeloid or lymphoid.  As a result, the bone marrow will be overcrowded with these abnormal, non-functional leukemic blasts  which replace the normal hemopoiesis that occurs in the bone barrow.  The numerous leukemic blasts may leave the bone and enter the peripheral circulation.  At the same time,  there is a severe reduction in mature blood cells being generated and enter the circulation. Thus, leukemia manifests as signs of the lack of those blood cells moreso than the presence of the leukemic blasts:  signs of anemia (lack of RBCs), abnormal bleeding (lack of platelets), and infections (lack of white blood cells). Diagnosis of leukemia first requires hematologic analysis of circulating blood for the presence of blasts and a reduction in blood cells.  This can then be followed up by samples of bone marrow (whether through aspiration or core biopsy) to assess the degree of blast formation and the stem cell affected. Treatment of leukemia focuses on eradicating the abnormal stem cell and blasts – often by chemotherapy or targeted immunotherapy.

Credits

Authors:  Dr. Jennifer Kong (BCIT & UBC), Emily Frawley (BCIT), Shing Tat Theodore Lam (UBC), William Wang  (UBC), Ghazal Sokhanran (UBC), Samuel Lam (UBC), Kristen Danielle Go (UBC)

Clinical aspects of leukemia  reviewed for accuracy: Dr. Michelle Wong (UBC)

Author of questions and exercises: William Wang, Ghazal Sokhanran, Samuel Lam, Kristen Danielle Go (UBC Undergraduate students) & Dr. Zoe Soon (UBC Okanagan)

Normal Hematology & Histopathology video:  Shing Tat Theodore Lam (UBC graduate student)

Medical illustrator:  Sarah Pinault (UBC Okanagan undergraduate student)

Medical Laboratory Technologists:

Blood collection:  Heather McMullen (BCIT & Vancouver Community College) & Emily Frawley & Julien Pho as contributors (BCIT)

LifeLabs:

Receiving:  Maria Arcila

Hematology:  Maryham Baghalha

Chemistry:  Norissa Toon

Hematopathologist:  Dr. Peter Van Den Elzen

Videoproducer:  Lindsay Belloc (BCIT)