Hematologic System Disorders

Introduction

Blood diseases can be associated with a number of different diagnoses. Blood disorders can indicate medical problems that either reside within another body system or are strictly connected to the blood cells. Some blood disorders due to bone marrow disease can be severe. This is because they affect blood cell formation and impact various blood cell functions throughout the body.

 

Red Blood Cell Disorders

Anemia is defined as low red blood cell (RBC) or hemoglobin concentration. Anemia is one of the major RBC disorders. Anemia can be caused by blood loss, destruction of RBCs, or inadequate blood cell production. Blood loss, or hemorrhage, can occur after trauma (such as a car accident) or surgery. Ulcers or tumors in the gastrointestinal tract can bleed as well. 

The symptoms of anemia can happen because of a lack of adequate RBCs available to carry oxygen to the body's tissues. People with anemia are often pale and weak. They complain of low energy levels. They may also experience shortness of breath. The acute treatment of anemia is a correction of the underlying problem and transfusion of red blood cells.

Sickle cell anemia (SCA) is a genetic disorder that's caused by abnormal hemoglobin production. Abnormal hemoglobin molecules are unable to carry appropriate amounts of oxygen and also make a rigid polymer that can occlude small blood vessels. The occlusion of blood vessels causes extreme pain, requiring hospitalization and treatment with pain relievers, such as acetaminophen (Tylenol), Ibuprofen (Advil), morphine, or fentanyl.

There's no definitive treatment option for SCA. Patients require frequent blood transfusions and also need treatment of severe pain during an SCA crisis. Some patients may require long-term treatment of pain associated with SCA.

 

Microcytic anemia is characterized by the formation of tiny RBCs. The main causes of microcytic anemia are iron deficiency and lead poisoning. Iron deficiency refers to the improper intake of iron or chronic diseases leading to iron deficiency. Mild forms of iron deficiency anemia can be treated by increasing the iron-rich food in your diet.

With microcytic anemia, the body forms very large RBCs. The main cause of microcytic anemia is a vitamin B12 and folic acid deficiency. This deficiency could be due to an inappropriate amount of vitamin B12 and folic acid in the diet or the result of another health condition or genetic disorder.

 

Anemia can be caused by certain chronic diseases, such as renal or kidney disease, cancer, and HIV. Kidney or renal disease can result in decreased production of erythropoietin, leading to anemia. Erythropoietin is a hormone produced in the kidneys that stimulates RBC production. Erythropoietin-stimulating factors are available in injectable forms to increase RBC production in these patients. Treatment of the underlying disease also reverses the anemia once the body starts producing normal amounts of erythropoietin.

Common medications for the treatment of anemia due to chronic diseases are Epoetin alpha (Epogen, Procrit) and Darbepoetin alpha (Aranesp).

The most common side effects of these medications are hypertension and thrombosis. Patients at increased risk of thrombosis due to other factors need to be watched closely for these side effects. For some patients, risks will need to be evaluated against benefits.

 

Hemolytic anemia is a result of decreased RBC survival time due to excessive hemolysis or destruction of RBCs. Excessive destruction of RBCs releases too much of the bile pigment bilirubin for the liver to handle.

Jaundice, the yellowing of the skin, is a sign of hemolytic anemia.

Treatment is generally focused on handling underlying disorders. Steroids and immune-suppressants are sometimes used to manage this type of anemia.

 

Aplastic anemia is caused by a condition of the bone marrow known as aplasia. In aplasia, the bone marrow cells fail to develop. The body doesn't produce enough leukocytes to help fight infections or enough platelets to help clot the blood. This very serious condition is often treated with blood transfusions.

 

White Blood Cell Disorders

Infections are the most common cause of an increased WBC count. They're treated with antibiotics based on the source of infection.

Another common WBC disorder is cancer. Cancer is treated with chemotherapy and radiation. Chemotherapy medications can also affect WBC count. These medications can cause neutropenia (decreased neutrophil count). Severe neutropenia increases the risk of infections because neutrophils are the main cells to defend against foreign pathogens.

 

Leukemia is a disorder in which the bone marrow produces an extreme abundance of WBCs. Leukemia is a type of cancer. It's caused by the production of WBCs going unchecked, which can destroy other blood cells. Some forms of leukemia afflict young children, but other forms are more common in adults.

 

There are two main types of leukemia. Acute (sudden onset) leukemia is a characterized by large numbers of undeveloped WBCs. Chronic (gradual development) leukemia has fully matured WBCs present. The subtypes of leukemia include

1. Acute myelogenous (or myelocytic) leukemia (AML)
2. Acute lymphocytic leukemia (ALL)
3. Chronic myelogenous (myelocytic) leukemia (CML)
4. Chronic lymphocytic leukemia (CLL)

Leukemia is treated with a combination of chemotherapy medications. The combination depends on the type of leukemia. When the patient goes into remission, a period in which the signs of disease are absent, a bone marrow transplant may be performed. You'll learn about chemotherapy medications in a different lesson of your course.

 

Lymphoma is another WBC disease. It's caused by cancerous tumor cells developing in the lymphatic system.

There are two types of lymphoma:

1. Hodgkin's lymphoma
2. Non-Hodgkin's lymphoma

Non-Hodgkin's lymphoma is more common than Hodgkin's lymphoma. The Reed-Sternberg cell is what separates Hodgkin's and Non-Hodgkin's lymphoma. If a doctor sees the Reed-Sternberg cell under a microscope, the lymphoma is classified as Hodgkin's.

Lymphoma is treated with a combination of chemotherapy medications.

 

Neutropenia is a condition in which the neutrophil count is decreased. Neutropenia is usually a side effect of medications such as chemotherapy medications, heparin, and antibiotics, but can also be the result of some genetic disorders. Dangerously low levels of neutrophils pose an extremely high risk of contracting various bacterial and fungal infections.

Treatment is the discontinuation of offending medications causing neutropenia. There are medications called granulocyte colony stimulating factors (gCSF) available that stimulate the production of neutrophils. Two common gCSF medications are

1. Filgrastim (Neupogen)
2. Pegfilgrastim (Neulasta) 

Patients with severe neutropenia are generally treated with a course of prophylactic antibiotics.

 

Platelet Disorders

Hemophilia is a genetically inherited disease. It's generally characterized by a deficiency of certain clotting factors (factor VII and factor IX), which prevents the blood from clotting.

These clotting factors are essential components of the coagulation pathway. Deficiencies of any of these clotting factors prevent blood from clotting, resulting in bleeding episodes. This means that a person with hemophilia may continue to bleed after getting a cut because the blood won't clot.

Hemophilia is treated by infusing factors that are available as injectable medications. Hemophilic patients may lose a lot of blood, which means many patients require frequent blood transfusions.

 

Thrombocytopenia is defined as an abnormally low level of platelets in the blood. It's a general condition that stems from an underlying disease. Low levels of platelets can be due to

• Chronic liver disease, causing the spleen to enlarge and destroy platelets
• Antibodies to platelets in some individuals
• Diseases of the bone marrow, resulting in adequate production of platelets
• Certain medications (such as Heparin)

Because platelets are involved in the initial steps of blood clotting, thrombocytopenia creates a risk for prolonged bleeding. In idiopathic thrombocytopenic purpura (ITP), a body's own antibodies destroy blood platelets. Spontaneous hemorrhages will appear in the skin, mucous membranes of the mouth, and internal organs. 

Treatment involves treating the underlying disease or discontinuing offending medications.

 

Arterial clots are blood clots that occur inside the arteries. Atherosclerosis results from the adherence of cholesterol, RBCs, platelets, fibrin, and other substances to an injured arterial wall that can result in a heart attack or stroke.

Venous clots are clots that occur in veins, usually in deep veins within the legs. Venous clots are generally characterized as deep vein thrombosis (DVT). If a venous clot breaks off and travels through the bloodstream, it's called embolus. Leg DTVs often travel to the lungs, causing pulmonary embolism (PE). PE is usually painful and fatal. A clot that develops in the heart can travel to the brain, causing a stroke.

Common cause of developing DVT are

• Trauma to blood vessels
• Clotting factor deficiencies
• Prosthetic heart valves
• Pregnancy
• Atrial fibrillation (A-fib), which means irregular heart rhythm
• Prolonged immobility 
• Orthopedic surgery
• Certain cancers
• Estrogen use

 

Antiplatelet medications disrupt platelet aggregation to help prevent a clot from forming.

Oral Medications

• Aspirin (Ecotrin)
• Dipyridamole (Persantine) 
• Clopidogrel (Plavix)
• Ticlopidine (Ticlid)
• Prasugrel (Effient)

Intravenous Medications

• Abciximab (Reopro)
• Eptifibatide (Integrilin)

One of the major side effects of antiplatelet medications is an increased risk of bleeding.

 

Anticoagulant medications disrupt the clotting pathway to slow or stop the clotting process. These medications don't 

• Require routine lab tests to adjust dosage and measure effectiveness
• Have many drug-drug interactions
• Have many drug-herbal interactions

One disadvantage is that a reversal agent to control bleeding may not be easily accessible. 

All anticoagulants increase the risk of bleeding, and patients are instructed to take these medications exactly as prescribed. Patients are also instructed to watch for any signs and symptoms of bleeding.

 

Key Points

Common medications related to blood disorders are shown below.

Generic name: Warfarin | Brand name: Coumadin | Prevents and treats DVT,  PE, and stroke

Generic name: Heparin | Brand name: Heparin | Prevents and treats DVT, PE, and stroke

Generic name: Darbepoetin alfa | Brand name: Aranesp | Treats anemia from chronic kidney disease (CKD)

Generic name: Filgrastim | Brand name: Neupogen | Treats neutropenia due to cancer or chemotherapy

Generic name: Clopidogrel | Brand name: Plavix | Prevents myocardial infarction (MI) and stroke

Generic name: Eptifibatide | Brand name: Integrilin | Prevents acute coronary syndrome (ACS) and percutaneous coronary intervention (PCI)

Generic name: Enoxaparin |Brand name: Lovenox | Prevents and treats DVT, PE, and stroke

Generic name: Rivaroxaban | Brand name: Xarelto | Prevents and treats DVT, PE, and stroke