Blood Review

• Blood is a connective tissue

• The blood is: 55% plasma, 45% formed elements (44% RBCs)

Blood Tests

• H & H: Hemoglobin and hematocrit, used for anemia testing

  • Hematocrit: % of any RBCs in any volume of blood (max is 44%)

• CBC: Complete blood test; measures hemoglobin, hematocrit, platelet and WBC count, used for infection

  • ALWAYS ordered with a differential

Anemia Definition

“Inability of the blood to supply the tissues with adequate oxygen for proper metabolic function”

• Either inadequate hemoglobin or RBC can lead to anemia

• Hg: hemoglobin concentration

• Hct: hematocrit concentration (packed cell volume)

• RBC: red blood cell count

• ANEMIA IS NOT A DISEASE; expression of an UNDERLYING disorder/disease

→ Normal Hg and Hct Levels

• Hg < 13 in men; Hct <41%

• Hg < 12 in women; Hct <36%

• Hg <14 in men; Hg <12 in women (with malignancy)

• Lastly, the anemia morphology:

  • Size: Macrocytic, microcytic, normocytic

    • Macro= the entire RBC

    • Micro= hemoglobin only

  • Hemoglobin content: Normochromic and hypochromic

• Microcytic, MCV < 80 (reduced iron availability)

• Normocytic, 80 < MCV < 100

• Macrocytic, MCV > 100 (liver disease/B12 deficiency)

Lab Values

• Hematocrit: volume of packed RBCs per unit of blood, expressed as a % (ex: 44% is the max)

  • 38-44% is in normal range

• Reticulocyte: young RBC, not functionally mature, anemia due to hemolysis or bleeding is characterized by reticulocytosis

  • Normal value: ~1%

  • Increase in reticulocytes is due to compensation to bring up the RBC

• Mean corpuscular volume (MCV): reflect average size or volume of RBC, will tell if the patient is micro, macro, or normcytic

• Mean cell hemoglobin concentration (MCHC): indicates the concentration of Hb in the average RBC, or the ratio of the weight of the Hb to the volume in which it is contained (chromicity/color)

Symptoms of Anemia

• Easy fatigue and loss of energy

• Tachycardia, rapid heart rate

• Shortness of breath

• Headache

• Difficulty concentrating

• Dizziness

• Pale skin

• Leg cramps

• Insomnia

Macrocytic Normochromic Anemia

Characterized by unusually large stem cells

• Can also be termed megaloblastic anemias

→ PATHOGENESIS:

• Defective DNA synthesis in rapidly dividing cells

  • Caused by B12 or folate deficiencies

1. Vitamin B12 deficiency:

   • Is B12 deficiency due to lack of intrinsic factor OR, normal intrinsic factor level, but not enough B12 absorption?

   • Autoimmune causes = pernicious anemia

   • Non-autoimmune causes = dietary, gastric bypass, tapeworm, pancreatic insufficiency

2. Folate deficiency: dietary or pregnancy causes

3. Other causes: alcohol use, drugs, malabsorption

Folate vs. B12 = The only difference is there are no neuro symptoms in folate deficiency

Pernicious Anemia

Macrocytic normochromic anemia

• Caused by autoimmune disorder to attack against parietal cells

• Lack of intrinsic factors

  • Intrinsic factor needed for B12 absorption → B12 deficiency

• S&S: Neurological

  • Paresthesia, pins and needles in hands or feet

  • Lost sense of touch

  • Wobbly gait or trouble walking

  • Clumsiness and stiffness of the arms and legs

  • Dementia → long term impact

• Diagnosis:

  • Antibodies against parietal cells

Folate Deficiency Anemia

Macrocytic normochromic

• Dietary intake related

• Impacts rapidly dividing cells

• Absorption of folate occurs in upper small intestine

• Not dependent on any other factors

• S&S:

  • Neuro symptoms not seen

  • Cheilosis, scales and fissures of the mouth

  • Stomatitis, painful ulcers of buccal mucosa and tongue

• Diagnosis:

  • Methylmalonic acid and homocysteine level (B12 vs. folate deficiency)

Microcytic Hypochromic

Characterized by RBCs that are abnormally small and contain reduced amounts of hemoglobin; IRON DEFICIENCY

• Disorders of iron metabolism, pophyrin and heme synthesis, and globin synthesis

• Etiology:

  • Iron deficiency is the most commonly seen

  • Thalassemia is rare

  • Sideroblastic anemia is also rare

  • Anemia of chronic disease

Iron Deficiency Anemia

Microcytic hypochromic

→ PATHOGENESIS:

• Chronic blood loss, #1 common cause (pathologic vs. physiologic)

  • Menstruation (physiologic)

  • Occult blood loss (cannot see where blood loss is coming from, pathologic)

  • Malignancy (blood loss that you can see, pathologic)

• Inadequate iron absorption (nutritional deficiency)

  • Diet low in heme iron (fish + meat)

  • Gastrointestinal disease or surgery (small intestine)

  • Excessive cow’s milk intake in infants (prevents iron absorption)

  • Pregnancy (physiologic demand increased)

• Malabsorption

• S&S: Impacts more of the epithelial

  • Symptoms of anemia plus;

  • Glossitis, smooth tongue

  • Restless legs

  • Angular stomatitis, cracking corners of the mouth

  • Koilonychia, thin brittle spoon-shaped fingernails

• Tests for Iron Deficiency:

  • Hgb: ⬇️

  • Hct: ⬇️

  • MCV: ⬇️

  • Serrum ferritin: ⬇️

  • Serum iron/transferrin: ⬇️

  • Peripheral blood smear

  • Bone marrow iron stain (invasive and painful)

• TREATMENT:

  • Oral iron salts; ferrous sulfate 325 mg po Q day (given to pregnant women)

  • Vitamin C can facilitate iron absorption or orange juice would suffice

  • DO NOT TRANSFUSE, UNLESS SEVERE (<6.5g/dl), considered aggressive form of treatment; will mask the issue

Normocytic Anemia

Acute blood loss

→ ETIOLOGY:

• Hemolysis: sickle cell disease (appears in waves, not constant, 4-6 years can sickle), immune system, transfusion rejection (mismatched blood type)

• Bone marrow suppression = myeloma

• Anemia of chronic disease = chronic kidney disease

• Hypothyroidism = slower production of RBCs

Anemia of Chronic Disease

Normocytic anemia → microcytic hypochromic

• Aka, anemia of inflammation

• Decreased erythropoiesis (low erythropoietin)

  • Impaired iron utilization

• INITIALLY normocytic-normochromic, but becomes microcytic-hypochromic

• Treatment is aimed at an underlying disorder

  • Results from:

    • Decreased erythrocyte life span

    • Suppressed production of erythropoietin

    • Ineffective bone marrow response

    • Altered iron metabolism in macrophages

      • Lead to anemia of chronic disease

Platelet Dysfunction & Coagulopathy

• Hemorrhage: extraversion of blood from vessels

• Hematoma: external or accumulation within a tissue

  • Benign (bruise) to fatal (retroperitoneal hematoma)

  • Jaundice

  • Large blood into cavities

• Petechia, minute (1-2mm in diameter)

• Purpura >3mm <1cm

• Ecchymoses 1-2cm

→ Coagulopathy

• Has 2 mechanisms

  • 1. Platelet issue (dysfunction)

  • 2. Coagulation cascade

→ Platelet Issue/Dysfunction

• Increased bleeding time in presence of normal platelet counts

• Disorders can be congential or acquired

• TESTING FOR PLATELET DYSFUNCTION:

  • Order a coagulation panel

    • PT → Goes with PTT

    • PTT → Goes with PT, tests for the intrinsic or extrinsic pathways or the clotting factors

    • INR → Anticoagulate in the US that is universally understood to not withdraw care by external physicians in the states or overseas

→ COAGULATION PATHWAY DYSFUNCTIONS

• Vitamin K deficiency, Hemophilia, DIC

• Intrinsic, extrinsic, and common pathways

von Willebrand Disease (Platelet Dysfunction)

• Autosomal dominant disorder

• MOST COMMON inherited bleeding disorder

• vWF facilitates platelet adhesion → causes mild or moderate bleeding

• Defective platelet adherence PFA-100 test

Vitamin K Deficiency (Coagulation Pathway Dysfunction)

→ Vitamin K deficiency (factors 2,7,9,10)

• Necessary for synthesis and regulation of prothrombin (2), the procoagulant factors (7,9,10) and proteins C and S (anticoagulants)

• Newborn/premature infants → liver not mature, get shot of vitamin K in bum right after birth

• Poor intake → seen in homeless population and in addicts

• Liver disease → seen with in combination with poor intake

• Defective absorption:

  • Generalized malabsorption → Crohns and Celiacs Disease

  • Biliary disease

→ PATIENT RISK:

• Diminished production by bacteria in gut (antibiotic treatment)

• Vitamin K antagonists

  • Warfarin (Coumadin) → blood thinner, cannot eat vitamin K rich foods or else it will counteract the treatment

• Heparin

• Certain antibiotics

Hemophilia (Coagulation Pathway Dysfunction)

• Inherited deficiency of factor 8 (hemophilia A) or factor 9 (hemophilia B) or factor 10 (hemophilia C)

• Sex linked inheritance, almost all patients are males

• Female carriers may have mild symptoms

• Most bleeding into joints, muscles, mucosal and CNS bleeding uncommon

Disseminated Intravascular Coagulation (Coagulation Pathway Dysfunction)

• DIC

• Develops RAPIDLY

• Acquired disorder in which clotting and hemorrhage simultaneously occur

• Endothelial damage/tissue factor is the primary initiator of DIC

→ PATHOPHYSIOLOGY:

• Increased protease activity in the blood caused by unregulated release of thrombin with subsequent fibrin formation and accelerated fibrinolysis

• Consumptive coagulopathy → uncontrolled hemostasis, patient bleeds out

→ ETIOLOGY:

• High mortality rate

• Infection by gram negative bacteria is the MOST COMMON CAUSE

• Carcinomas/leukemias

• Trauma, pregnancy (amniotic fluid gets into mother’s blood stream), transfusion reaction

• Clinical signs and symptoms demonstrate wide variability:

  • Bleeding from venipuncture sites

  • Bleeding from arterial lines

  • Purpura, petechiae, and hemotomas

  • Symmetric cyanosis of the fingers and toes