Chapter 8 Blood and Clotting PDF

8 BLOOD AND CLOTTING Allison Rusgo, Megan E. Schneider, Daniela Livingston, and Patrick C. Auth Overview of Blood and Clotting ages 0 to 9 and eighth for ages 10 to 24.1 I...

8 BLOOD AND CLOTTING Allison Rusgo, Megan E. Schneider, Daniela Livingston, and Patrick C. Auth Overview of Blood and Clotting ages 0 to 9 and eighth for ages 10 to 24.1 In the Red Blood Cells United States, the National Health and Nutri- General Concepts in Anemia tion Examination Survey (NHANES) data show iron deficiency anemia prevalence to be 10.4% Hemostasis of women and 5.2% of men. Non-Hispanic Black Coagulation Cascade females had the highest prevalence at 20.3%.2 Thromboembolic States Disorders of clotting are also very common, with ischemic heart disease and stroke being the States of Excess Bleeding two leading causes of disability globally in adults Pediatric Considerations ages 50 to 74 and 75+.1 Heart disease remains the Development of the Blood Cells leading cause of death in the United States.3 As Common Blood Disorders in Children risk factors for heart disease and stroke, athero- sclerosis and atrial fibrillation (AF), respectively, Gerontological Considerations are very prevalent in the United States. Epidemi- Structural Changes With Age ologic data from the American Heart Association Functional Changes With Age show that prevalence of coronary heart disease is Anemias Commonly Seen in Older Adults 7.4% in males and 4.1% in females; stroke preva- lence is 3.1% in males and 2.6% in females.4 The Case Study 8.1: A Patient With Pernicious Anemia most common cause of death is myocardial in- Case Study 8.2: A Patient With a Deep Venous farction, often caused by blood clot formation sec- Thrombosis and COVID-19 ondary to coronary atherosclerosis. AF promotes Bridge to Clinical Practice clot formation, which significantly increases risk of stroke. Among the top 100 prescribed drugs in the United States are several that affect blood clotting and are used to reduce morbidity and THE CLINICAL CONTEXT mortality from coronary artery disease and stroke. Risk reduction in patients diagnosed with acute B lood disorders vary from the very common (iron-deficiency anemia) to the rare (heredi- tary spherocytosis) and encompass disorders of coronary syndrome includes treatment with the antiplatelet agents clopidogrel (no. 29) and aspi- rin (no. 36). Patients at risk for embolism due to red blood cell production and function, platelet AF or venous thrombosis are managed with an- disorders, and disorders of bleeding and clotting. ticoagulants such as apixaban (no. 48), warfarin Anemia has been identified as one of the greatest (no. 58), and rivaroxaban (no. 86).5 Management global health challenges, ranking 25 out of 369 of both anemia and anticoagulant therapy is com- diseases for all age groups globally in 2019.1 The mon in primary care settings, which are also the burden of dietary iron deficiency is highest among sites of initial identification of many other disor- children, ranking seventh globally for children ders of red blood cells, platelets, and clotting. 247 Copyright © 2025 Springer Publishing Company LLC Sharing/distributing/reproducing prohibited by law (CC) 248 Advanced Physiology and Pathophysiology: Essentials for Clinical Practice, Second Edition adult women averages 11 to 16 g/dL; in adult men it OVERVIEW OF BLOOD AND CLOTTING averages 14 to 18 g/dL. Lower values for hematocrit or hemoglobin are diagnosed as anemia. Blood circulates throughout the cardiovascular sys- In order to carry oxygen to the tissues of the body, tem in order to supply oxygen and nutrients to the RBCs must have a size and shape that allow them to body’s tissues and organs. Without adequate blood travel through very small capillaries. The biconcave supply, tissues become ischemic and can die. The es- disk of the RBC is 7 to 8 µm in diameter and 2 µm thick, sential functions of the blood are carried out by the which allows for optimal diffusion of gases across the many and various components of the blood. Red blood membrane. RBCs also have the capacity to be revers- cells (RBCs) deliver oxygen to the tissues and remove ibly deformed, which allows the cells to become more by-products of cellular metabolism, such as carbon di- compact to squeeze through smaller capillaries, which oxide. Blood also transports white blood cells (WBCs), can be only 5 µm in diameter, and then return to their platelets, and proteins of the coagulation, complement, original shape. Specific characteristics of the cells are and kinin systems to sites of injury and pathogen in- quantified using several key indices: vasion. Additional functions of blood include regulat- ing body temperature, maintaining acid–base balance, transporting nutrients to tissues and discarding wastes, RBC size is estimated as the mean corpuscular volume (MCV), calculated by the laboratory as the and carrying hormones to target tissues. hematocrit divided by the RBC count. Differential Blood is composed of plasma and formed elements. diagnosis of many RBC disorders includes identi- Plasma makes up approximately 55% of the whole fication of macrocytosis (increased MCV, >100 fL), blood volume. Ninety percent of plasma is water; the microcytosis (decreased MCV,