Hematology Lab Tests & Clinical Significance

Hematology Lab Tests & Clinical Significance

• Normal hemoglobin ranges for males are 13.5-17.5 g/dL, and for females, 12-16 g/dL; low levels indicate anemia, while high levels indicate polycythemia
• Hematocrit reflects the percentage of RBCs in blood, with normal ranges for males being 41-53% and for females, 36-46%; low levels indicate anemia, and high levels, dehydration/polycythemia
• Mean Corpuscular Volume (MCV) normal range is 80-100 fL, an MCV <80 indicates microcytic anemia (iron deficiency, thalassemia), and >100 indicates macrocytic anemia (B12/folate deficiency)
• Red Cell Distribution Width (RDW) normal range is 11.5-14.5%; an increased RDW can indicate iron deficiency anemia but is usually normal in thalassemia
• The normal range for reticulocyte count is 0.5-2.5%; high counts indicate increased RBC production (hemolysis, bleeding), while low counts indicate bone marrow failure
• Serum iron normal range is 60-170 mcg/dL; low levels indicate iron deficiency anemia, while high levels indicate hemochromatosis
• Total Iron Binding Capacity (TIBC) normal range is 250-450 mcg/dL; high levels indicate iron deficiency, while low levels indicate anemia of chronic disease
• Male ferritin normal range is 30-400 ng/mL, and for females, 13-150 ng/mL; low levels indicate iron deficiency, while high levels indicate inflammation or hemochromatosis
• Vitamin B12 normal range is 200-900 pg/mL with low levels indicate B12 deficiency anemia (pernicious anemia, malabsorption)
• Folate normal range is 2-20 ng/mL with low levels indicate folate deficiency anemia
• Haptoglobin normal range is 30-200 mg/dL low levels indicate hemolytic anemia
• Lactate Dehydrogenase (LDH) normal range is 140-280 U/L; high levels indicate hemolysis or leukemia
• Peripheral Blood Smear is used to differentiate anemia types by identifying sickle cells, schistocytes, spherocytes, and Howell-Jolly bodies

Microcytic Anemias

• Iron Deficiency Anemia can be caused by chronic blood loss which results in decreased Hgb, Hct, MCV, and ferritin. With those decreased it causes an increase in TIBC and RDW
• Thalassemia is caused by genetic disorder (alpha or beta chain defects). Lab findings reveal decreased MCV, normal RDW and ferritin. Target cells are seen on the smear.
• Lab findings in anemia of chronic disease show normal or elevated levels of ferritin, decreased serum iron, and either normal or reduced MCV and TIBC
• Lead poisoning is caused by environmental exposure, that leads to microcytic anemia and basophilic stippling on the smear

Normocytic Anemias

• Acute Blood Loss often caused by trauma which will affect Hgb, Hct and MCV but shows an increase in reticulocytes
• Hemolytic Anemia is often autoimmune but can be G6PD or sickle cell related, shows decreased Hgb, increased reticulocytes, LDH, indirect bilirubin and the presence of Schistocytes on smear
• Aplastic Anemia is related to bonemarrow failure and will show decreased WBC, RBCs and platelets
• Anemia of Chronic Disease often results from long term chronic infections which will reveal normal or low MCV, TIBC and/or Ferritin levels

Macrocytic Anemias

• Vitamin B12 Deficiency (Pernicious Anemia) is a result of the lack of intrinsic factor which will result in elevated MCV, hypersegmented neutrophils, and other signs
• Elevated Homocysteine and Methylmalonic acid (MMA) are found in Vitamin B12 Deficiency (Pernicious Anemia)
• Folate deficiency resulting from alcoholism, impacts the MCV and neutrophils while showing elevated levels of Homocysteine but normal MMA
• Macrocytosis occurs alongside target cells when Liver disease occurs
• Myelodysplastic syndrome will impact MCV and show dysplastic RBCs and WBC on a smear

Additional Information for CBC

• Neutrophils are the greatest number on CBC when healthy
• MCH is Normal when Normochromic
• Platelet counts below 10.000 can indicate the risk of epistaxis

Sickle Cell Anemia (SCA)

• SCA is an autosomal recessive hemoglobinopathy stemming from a beta-globin gene mutation of the HBB on chromosome 11, causing hemoglobin S (HbS) formation
• HbS polymers develop under low oxygen, deforming RBCs into a sickle shape
• Vascular occlusions and hemolysis result from rigid, sickled RBCs

Effects of Chronic Hemolysis and Vaso-occlusion.

• Chronic hemolysis causes anemia, raised bilirubin, and reticulocytosis
• Repeated vaso-occlusion results in ischemia, infarction, and organ damage throughout the body

A Medical Emergency and Complications

• In SCD, fever indicates a medical emergency from potential sepsis due to asplenia
• Vaso-occlusive crisis is managed with hydration, pain management and oxygen
• New pulmonary infiltrate and hypoxia are signs of acute chest syndrome
• Exchange transfusions and MRI/MRA screenings (ages 2-16) are treatments for Strokes
• Splenectomy treats recurrent cases for Splenic Sequestration
• Pain is a key indicator for Avascular Necrosis
• Infections are prevented via Penicillin prophylaxis and vaccines

Key Laboratory values for SCD

• Expected findings in SCA will show decreased Hgb, increased Reticulocytes, Sickled RBCs, and Haptoglobin
• The gold standard for SCD diagnosis is Hemoglobin Electrophoresis revealing HbSS

Management

• Hydroxyurea is the first line of treatment for SCA that increases HbF, reducing sickling and crises
• Folic acid supplementation supports RBC production, addressing deficiency from chronic hemolysis
• Regular vaccinations, including pneumococcal and influenza, are needed for infection prevention
• Transfusions helps prevent strokes, severe ACS, and crises but run the risk of overload that requires Chelation therapy

Anemias: Key Points

• Anemia is characterized by decreased red blood cell (RBC) mass, hindering oxygen delivery
• Key diagnostic levels for anemia are a Hgb <13.5 g/dL (male) and <12 g/dL (female); Hct <41% (male) and <36% (female)
• Primary causes of anemia include decreased RBC production, increased RBC destruction, and blood loss
• High-risk groups like infants, pregnant women, and the elderly should be screened for anemia
• A board tip is for Paresthesia with Macrocytosis indicates a risk fo B12 Deficiency
• Check Iron studies when MCV levels are <80
• Check B12/Folate levels when MCV levels are >100

Common Anemias and Management

• S/S for koiloychia include Malaise, Drowsiness and a sore tongue and should be treated with 325mg of ferrous sulfate tabs TID one hour before or after meals with 250mg or Vit C
• Management may often indicate transfusions as well as Iron Chelation

Outpatient Oral Anticoagulant Therapy

• Anticoagulants prevent thromboembolic disorders
• Warfarin requires frequent monitoring and INR levels and has dietary restrictions
• DOACs offer fewer restrictions for dietary regulation

Diabetes Mellitus Type 1

• T1DM results from autoimmune destruction of pancreatic beta cells, leading to absolute insulin deficiency
• T1DM is insulin-dependent and unrelated to obesity and requires constant, life long insulin therapy
• Diagnosis for T1DM requires fasting blood glucose greater than 126mg/dL or 2-hr greater than 200mg/dL
• GAD-65 Autoantibodies are the most common autoimmune markers
• Low C-peptide and positive GAD-65 equal T1DM for a board tip
• Start screening for nephropathy, retinopathy and neuropathy five years after having T1DM
• Basal Insulin prevents fasting hyperglycemia but keep in mind that nocturnal hypoglycemia may occur for very active patients

Thyroid Disordes

• Hyperthyroidism is a condition in which thyroid hormone exerts greater than normal response
• The most common cause for Hyperthyroidism is Grave's disease
• First line treatment of Hyperthyroidism includes beta-blockers at 10-40mg TID
• To consider the treatment option, the value of TSH must be considered
• Hypothyroidism (the opposite of Hyperthyroidism in which the body doesn't produce enough of this) involves fatigue, weight gain, and cold tolerance
• TSH must be the best screening test available and note if serum free T4 concentration falls
• Low C-peptide and positive GAD-65 equals T1DM for a board tip
• Start screening for nephropathy, retinopathy and neuropathy five years after having T1DM
• Basal Insulin prevents fasting hyperglycemia but keep in mind that nocturnal hypoglycemia may occur for very active patients