E1: Complete Clinical Lab Medicine Review

which tube/anticoagulant is used for routine chemistry panels?

which tube/anticoagulant is used for routine chemistry panels?

plain red (no coagulant)

which tube/anticoagulant is used for hematology?

lavender/purple, EDTA
*requires inversion to prevent clotting

which tube/anticoagulant is used for coagulation?

light blue, sodium citrate
*requires inversion to prevent clotting

which tube/anticoagulant is used for glucose?

Gray, potassium oxalate

What is the difference between plasma and serum?

Serum is liquid portion of clotted blood lacking coagulation proteins (proteins were used in clotting process) while Plasma is the liquid portion of anticoagulated whole blood that does contain coagulation proteins (proteins have not yet been used to form clot)

What abnormalities are present when the RBCs are hemolyzed in the sample?

-increase level of serum potassium, magnesium, phosphorus, lactate dehydrogenase (LD), and acid phosphatase levels
-RBC/WBC count is decreased

Which gauge of needle is appropriate for venipuncture?

20-22g for routine blood collection
*smaller than 22g is not appropriate b/c it could causes hemolysis.
14-16g for blood donations

Which artery is most commonly used for an arterial blood sample? What PE test is necessary? Why?

-radial artery in wrist or brachial artery in the antecubital space
-modified Allen Test to determine adequate circulation through the ulnar artery

Which tests need to be done after the patient has been fasting?

glucose and triglyceride levels

What tests are elevated due to strenuous exercise?

-Can increase serum enzyme levels for creatine kinase and lactate dehydrogenase
-increased blood lactate level, serum potassium levels, WBC count, hematuria an proteinuria

How is a 24 hr urine sample collected?

1. record time of first void although pt DOES NOT keep first void
2. record times and collect all voids except for the first for the span of 24 hours
*keep urine in refrigerator, preferably in a dark container
3. label specimen container and deliver to lab promptly

What are the effects of improper storage of the urine sample?

-bacterial growth
-nitrite
-pH
-turbidity
-decrease in glucose, ketones, bilirubin, and urobilinogen
-disintegration of formed elements such as cell, casts and crystals
-color change

What are the causes of anemia?

-increased destruction of RBC (hemolytic anemias)
-decreased production of RBC (aplastic anemia)
-excessive blood loss (such as GI bleeding)

What abnormalities of anemia are seen on the CBC?

- decreased hemoglobin (Hgb/Hb) and hematocrit HCT)
- there does NOT need to be a decreased RBC count

What is aplastic anemia?

caused by aplasia (failure to develop normally) of bone marrow or its destruction by chemical agents (medications) or other physical factors

What is hematopoiesis? Where does it occur?

-The process of blood cell production and development.
-These stem cells are found in bone marrow, continuously self replicate and proliferate, are under the influence of cytokines and differentiate into progenitor cells
-prior to birth hematopoiesis occurs in the yolk sac
- after birth it occurs in the bone marrow
-birth to 20 years it takes place in long bones
-20 years and on takes place in flat bones, vertebrae and pelvis

Which stain is used for a peripheral blood smear?

Wright-Giemsa stain with EDTA (purple top tube)

What is a WBC differential? What else is examined on the peripheral blood smear?

it can identify & quantify WBC types c/ blood smear
can also identify cell size, nucleus and cytoplasm features. Identification and estimation of abnormal RBC morphology and estimation of platelet count, exam for platelet clumping

What is a reticulocyte, and what does the reticulocyte count reflect?

-RBC that leaves the bone marrow and travels to the peripheral circulation, immature (fully mature into RBC within 1-2 days).
-reticulocyte count reflects the number of maturing RBCs in peripheral circulation and tells you if the bone marrow is functioning properly

What causes an increased reticulocyte count?

Defined by high RBC precursors in bone marrow, decreased release of RBC into peripheral blood
Can be due to increased destruction of RBC precursors due to external circumstances (causing your body to make a bunch)
Normal destruction in the bone marrow is <10% of developing RBC
Examples of this include sickle cell anemia, G-6-PD deficiency, autoimmune antibody formation, acute or chronic bleeding, and following treatment for iron deficiency anemia or factor deficiency anemias.

What causes increased destruction of RBCs?

Hemolytic anemia is caused by increased destruction or shortened life span of RBCs. It is classified by whether the RBC defect is intracorpuscular or extracorpuscular. It can be caused by autoimmune problems, genetic defects (sickle cell, thalassemia, and G6PD deficiency), exposure to chemicals/medicines/toxins, infections, blood clots in small vessels, or transfutions from a donor with a different blood type.

Describe the appearance of reticulocytes with wright's stain.

cells are slightly larger than mature RBC's and appear blue or gray due to residual RNA present in the cells

What does tissue hypoxia cause? Which organ and which hormone?

If oxygen delivery to the body tissue is decreased, tissue hypoxia occurs. Tissue hypoxia in the kidneys stimulate increased production of erythropoietin (EPO) from the kidneys. Increased levels of EPO accelerates the erythrocyte development in bone marrow.

What is the lifespan of an RBC? Where does destruction occur?

Maturation in bone marrow through the orthochromic normoblast (metarubricyte) takes 5 days, after that the reticulocytes mature in 1 - 2 days in the peripheral circulation. The overall life span of RBCs is about 120 days. The again RBCs are removed by fixed macrophages in the body's reticuloendothelial (RE) system where the hemoglobin is broken down. This happens primarily in the spleen.

Which RBC indice indicates the size of the RBC?

Mean corpuscular volume (MCV) represents the average RBC volume. Useful for classifying anemias as normocytic, microcytic, or macrocytic.

Which RBC indice indicates the Hemoglobin content of the RBC?

Mean corpuscular Hgb (MCH) estimates the average weight of hemoglobin in each RBC. Anything less than the reference range is considered hypochromic.
Mean corpuscular Hgb content (MCHC) estimates the concentration of hemoglobin in each RBC. It is the ratio of the weight of hemoglobin to the volume of the RBC.

Which RBC indice reflects variability of cell sizes? What is the term for increased variability of cell sizes on peripheral smear?

RBC distribution width (RDW) is a measure of anisocytosis or the size variation in a population of RBCs. It represents the coefficient of variation (CV) of red cell size.

What is the most common cause of megaloblastic anemia? Which RBC indice is abnormal in megaloblastic anemia?

The most common cause of megaloblastic anemia is the deficiency of either vitamin B12 or folate. The RBC indices that is abnormal with megaloblastic anemia are the presence of macrocytic ovalocytes, Howell-Jolly bodies, and abnormal erythropoiesis. The WBC indices that is abnormal with megaloblastic anemia are the presence of hypersegmentation.

What are some inclusions seen in RBCs and WBCs?

- RBCs include Howell-Jolly Bodies, Basophilic stippling, Pappenheimer bodies, and Heinz bodies.
- WBCs include neutrophil cytoplasmic inclusions such as toxic granulation, vacuolization, and Dohle bodies

What are the functions of the WBCs?

-function in host defense via phagocytosis and immune response

What do toxic granulation and vacuoles indicate?

Toxic granulations are commonly seen in acute infections, particularly bacterial infections

Name the different types of WBCs

neutrophils, lymphocytes, monocytes, eosinophils, basophils

Where are megakaryocytes and what do they do?

Megakaryocytes are the mature cells of platelets found in bone marrow. It splinters into fragments, enclosed by a membrane, and moved in to the peripheral blood circulation to create the platelets for clot formation.

What is an erythrocyte sedimentation rate?

Erythrocyte sedimentation rate (ESR) provides a means of detecting inflammatory conditions. Normally blood settles relatively slowly, but if the blood is settling faster than normal, it could indicate an inflammatory condition. It is a very nonspecific test and is discouraged at some labs.

What is a C-reactive protein test?

C-Reactive Protein test measures the level of plasma protein produced by the liver cells in response to acute inflammation or infection. CRP is a better indicator of inflammation than ESR, is more sensitive, and responds more quickly to change in the clinical situation.

Why is a G6PD deficiency significant?

G-6-PD is part of the pentose phosphate pathway to protect hemoglobin from the effects of oxidizing agents. Exposure of RBCs in persons affected by G6PD deficiency to oxidizing drugs causes RBCs to lyse.

What is a bone marrow aspirate indicated for?

Bone marrow studies are used to diagnose polycythemia vera, acute and chronic leukemias, myelodysplastic syndromes, and aplastic anemias

How is anemia classified?

Anemia is a condition in which the oxygen carrying capacity of the blood is reduced and defined by low Hgb and low HCT. It may be caused by increased destruction of RBCs, decreased production of RBCs, or excessive bleeding. It is classified by size (micro-, normo-, or macrocytic) or color (hypo- or normochromic) abnormalities of the RBC.

What is hemoglobin composed of?

Hemoglobin is composed of four globin chains (two alpha or zeta and two non-alpha) with four heme molecules

What 3 parts are needed for hemoglobin synthesis to occur? What stage in Erythropoiesis does it occur?

Iron Delivery, Heme synthesis, Globin chain synthesis
Iron - transferrin transport
Heme in Mitochondria
Cytoplasmic polyribsomes for goblin chains
Hemoglobin synthesis begins in the polychromatophilic normoblast, the highest amount of heme is in the orthochromic normoblast.

What is carboxyhemoglobin? Methemoglobin?

-Carboxyhemoglobin is a hemoglobin-CO complex, normally is very low but increased with CO poisoning.
-Methemoglobin happens when Fe3+ cannot be reduced to Fe2+ and oxygen cannot be transported in the hemoglobin. Reduced carrying capacity of the hemoglobin can cause cyanosis or hypoxia.

What is the pathophysiology of Hgb SS?

Hgb SS is sickle cell anemia which is a defective hemoglobin molecule with a damaged membrane that results in a sickled-shape when the RBC is deoxygenated. The heterozygous version (Hgb AS) is sickle cell trait which is a normal gene and a sickle gene. The homozygous version (Hgb SS) is sickle cell disease which is two sickle genes. In the normal amino acid sequence, a Glu is in the 6th position. In Hgb SS, a Val has replaced the Glu. The sickled cell cannot fit in the capillaries.

What is alpha thalassemia? Beta thalassemia?

Thalassemia is a condition when the globin chain production is reduced or absent.
-Alpha Thalassemia is a lack of alpha globin chain production
-Beta Thalassemia is reduced (minor) or absent (major) beta chain production

What is the best test to evaluate for hgb abnormalities?

The best way to test for abnormal hemoglobin is with an EDTA anticoagulated whole blood specimen (lavender/purple top) and performing a hemoglobin electrophoresis

Where is the majority of iron in the body?

Majority (approx. 70%) of the iron in the body is found in the hemoglobin (RBC)

How is iron transported? What are the storage forms of iron?

Iron must be transported using transferrin. Normally only about 1/3 of transferrin total binding sites contain iron. It travels to sites of erythropoiesis (RBC synthesis in bone marrow) and storage sites (RE cells). Storage forms of iron are ferritin (soluble) and hemosiderin (insoluble).

Which test is best to evaluate iron body stores?

Testing serum ferritin levels (Fe2+ and apoferritin) is the best way to test iron body stores. It is routinely ordered with serum iron levels and TIBC

What are the causes of Fe deficient anemia?

The most common cause of iron deficient anemia is chronic blood loss such as GI bleeds and heavy menstrual bleeding. Other sources of Fe deficient anemia are increased body iron usage (pregnancy or lactation), inadequate dietary iron intake, and decreased absorption (intestinal disorders, post-small bowel resection, or Vitamin C deficiency)

What is the pathophysiology of sideroblastic anemia?

- a group of disorders with defective incorporation of iron into the heme molecule. It can be inherited or acquired. The body responds to deficient heme synthesis by increasing intestinal absorption of iron and iron transport to red bone marrow. The underlying disorder prevents iron insertion into the porphyrin ring which results in accumulation of iron in the mitochondria of RBC precursors.

What is hemochromatosis?

Hemochromatosis is an inherited autosomal recessive disorder which results in an idiopathic increase of iron absorption in the intestine, up to 4mg/day and it is not matched by increased iron excretion. A slow, chronic build up on iron results in accumulation of iron outside the RE cells causing injury to many organs.

What are petechiae, purpura and ecchymosis?

-Petechiae: small, pinpoint intradermal hemorrhages. Can be caused by platelet or coagulation defects, infectious diseases, DIC, or septicemia
-Purpura: group of petechiae, most are non-palpable but can be palpable
-Ecchymosis: "bruise" intradermal hemorrhage larger than purpura

How does aspirin affect platelets?

it inhibits the COX enzyme in platelets leading to the reduced formation of prostaglandin G2 -> platelets are not able to extend pseudopods. Platelets are prevented from signaling each other reducing the number of platelets that adhere to the injury . Effect of aspirin lasts the entire life span of platelets (roughly one week, this is why you stop aspirin 1 week prior to sx)

What is exposed during an injury to the bloodstream to start the coagulation process?

The subendothelial and endothelium are damaged during injury to vessels which causes collagen and tissue thromboplastin to be exposed to circulating blood. Platelets begin to adhere to injury site, initiating the intrinsic coagulation pathway. Tissue thromboplastin will activate Factor VII which initiates the extrinsic coagulation pathway. From there, at Factor X the common pathway will take place and end in fibrinolysis (the breakdown of fibrin).

Which studies assess platelet function?

- Bleeding time (BT): small incision is made on volar surface and you calculate time if takes for blood flow to stop, BP cuff is inflated to 40mmHg. Greatest risk is BT > 15 min
- Platelet Closure Time (PCT): citrate blood (light blue top), differentiates between pathology and aspirin use, sensitive to platelet adhesion and aggregation, normal or abnormal reading

How do platelets and vonWillibrand factor interact?

The adhesive protein von Willebrand factor (vWF) contributes to platelet function by mediating the initiation and progression of thrombus formation at sites of vascular injury.

Which factors are vitamin K dependent?

Factors II (prothrombin), VII (stable factor), IX (Christmas factor), and X (Stuart-Prower factor) are Vitamin K deficient. Individuals with liver disease are deficient in Vitamin K dependent factors and commonly have impaired blood coagulation

Which factor is the starting point of the common pathway?

Factor X (Stuart-Prower Factor) initiates the common pathway. Tissue factor and Factor VIIa lead to Factor X to start the common pathway. Factor VIII and Factor IX work together to activate Factor X in the common pathway

What does the PT test assess? What is coumadin indicated for?

-Prothrombin Time (PT) assesses the extrinsic and common coagulation pathway, it screens for deficiencies of Factor I, II, V, VII, and X, and monitor anticoagulation therapy - especially Coumadin. This test is performed on citrated blood (light blue top tube), calcium and tissue thromboplastin (tissue factor) are added to the patient's plasma and the time necessary for clot formation is measured.
-Coumadin is given to patients that have medical conditions such as a.fib, DVT, and heart valve replacement, to prevent development of very small blood clots. The blood of patients taking Coumadin will have delayed clotting

What does the aPTT test assess?

Assesses the intrinsic and common coagulation pathway. It is performed on citrated blood, calcium + phospholipid + contact activator (kaolin) are added to patient's plasma, and the time necessary for clot formation is measured. It is used to monitor heparin anticoagulant therapy, screen for coagulation disorders, and evaluate liver function (synthesis of Factors IX, XI, and XII).
Heparin enhances the activity of Antithrombin III by 1000-fold

How is fibrinolysis initiated?

-Intrinsic activation - upon initiation of the intrinsic coagulation pathway
-Extrinsic activation - upon release of tissue plasminogen activator (tPA) from the subendothelium of injured blood vessels
-Exogenous activation - use of therapeutic thrombolytic agents such as tPA, urokinase, and streptokinase

What is plasmin? What results from plasmin interacting with fibrin?

Plasmin is a proteolytic enzyme that degrades fibrin. The bound plasmin digests fibrin (and fibrinogen) into small fragments known as fibrin degradation products (FDP). FDPs normally control coagulation by interfering with the polymerization of fibrin monomers in the common pathway.

What does an elevated D-dimers indicate?

Fibrin fragments still cross-linked by Factor XIIIa are referred to as D-dimers. An increase in D-dimers indicate an increase in clot formation and active fibrinolysis. Excessive plasmin activity will result in abnormally high levels of FDPs and D-dimers.
D-dimer assay is used mainly to assess a patient for the presence of DVT, PE, and DIC

What are protein S and protein C?

Protein C is a vitamin K dependent enzyme produced by the liver and it circulates in plasma in an inactive form. In its active form, it inactivates Factors Va and VIIIa (inhibits both the intrinsic and extrinsic coagulation pathways).
Protein S is also a vitamin K dependent enzyme produced by the liver.
Protein S is a cofactor for Protein C to be fully effective
<b>A decrease in the concentration of either of these proteins increases the risk of intravascular coagulation</b>

What is ITP?

Idiopathic (Immune) thrombocytopenic purpura (ITP) is an autoimmune disorder in which an IgG autoantibody is formed that binds to platelets and cause their destruction. It most often occurs after a viral illness. Patients suffer from petechial hemorrhages, purpura, bleeding from the gums, GI tract, and urinary tract. Bleeding is often spontaneous and can last for hours but is self-limiting.

What is vonWillebrands disease?

MOST COMMON CONGENITAL DISORDER OF HEMOSTASIS
Caused by a deficiency of von Willebrand Factor and can cause reduction of platelet adhesion. Bruising, epistaxis, and post-surgical bleeding are the most common manifestations
Patient will have a normal number of platelets, but they don't function properly

What is hemophilia A and B?

-Hemophilia A (classic hemophilia) is an X-linked recessive disorder in which there is a deficiency of Factor VIII. This causes severe and prolonged post-traumatic bleeding and can also manifest as severe, spontaneous bleeding.
-Hemophilia B (Christmas disease) is an X-linked recessive disorder in which there is a deficiency of Factor IX. It has the same symptoms as Hemophilia A, though less severe in some patients. They are indistinguishable by patient history and symptoms alone
Patients are more likely to be deficient in Factor VIII than Factor IX
*if you suspect patient has hemophilia, order a Factor VIII assay

What is DIC?

Disseminated Intravascular Coagulation (DIC) is characterized by hyper-stimulation of all coagulation and fibrinolytic activity simultaneously. This condition affects the entire body. Platelets and coagulation factors are consumed in the process, diffuse small thrombi are formed, patients develop petechiae indicating the presence of microthrombi, then the patient develops organ failure.

Why do patients with severe liver disease have coagulopathies?

Diseased livers cannot adequately clear activated coagulation factors, resulting in bleeding disorders. Vitamin K dependent factors are affected first and can cause abnormal hemostasis. The earliest indicators are prolonged PT and aPTT. Impaired platelet function commonly occurs in alcoholics. Antithrombin III, Protein C, and Protein S are also deficient due to the inability of the liver to synthesize these substances. The patient has an increased risk of clot formation as well.

What is myelopoiesis?

growth and development of granulocytes and monocytes in bone marrow

how long does complete maturation of WBC take in the bone marrow?

7-11 days

What is Porphyria cutanea tarda and what causes it?

Enzyme deficiency/dysfunction with normal heme synthesis pathway
Heme intermediates accumulate in tissue
Cutan = skin
Sun exposure = blistering, erosions, ulcerations, fragile skin, scarring, desire of iron rich foods

What will you see on Iron study labs for IDA (Iron Deficiency Anemia)?

-low iron
-high TIBC
-low ferritin

What is a left shift and how is it determined?

"left shift" indicates that the neutrophils present in the blood are at a slightly earlier stage of maturation than usual. Results in increased number of band neutrophils and usually indicates an acute bacterial infection
- "bandemia"

What RBC morphologies are associated with DIC, sickle cell crisis, severe burns, multiple myeloma, hereditary spherocytosis, and G6PD deficiency

-DIC: acanthocytes (3-8 fingerlike projections), cell membrane with increased levels of cholesterol
-sickle cell crisis: schistocytes (bizarre shaped cell fragments)
-severe burns: Burr cells (10-30 rounded spicules)
-multiple myeloma: rouleaux (cells partially adhering to each other
-hereditary spherocytosis: spherical cell with decreased surface membrane which appear microcytic and "hyperchromic" due to loss of central pale area. Irreversible shape. Can also see stomatocytes (rectangular or slit like central pale areas)
-G6PD deficiency: Helmet (bite) cells, distinctive projections as a result of splenic removal of inclusion bodies. Heinz bodies (scattered blue dotlike structures varying in size)

Which tube/anticoagulant is used for arterial blood gas

green top tube

Which tube/anticoagulant is used for troponin

green top tube

Which tube/anticoagulant is used for ammonia

lavender/purple top tube

Which tube/anticoagulant is used for blood bank testing

lavender/purple top tube

Which tube/anticoagulant is used for blood alcohol testing

gray top tube

What causes increased destruction of RBCs?

-increased destruction or shortened life span of RBCs. It is classified by whether the RBC defect is intracorpuscular or extracorpuscular. It can be caused by autoimmune problems, genetic defects (sickle cell, thalassemia, and G6PD deficiency), exposure to chemicals/medicines/toxins, infections, blood clots in small vessels, or transfusions from a donor with a different blood type

What is the INR test? What are the normal ranges for PT & INR?

-INR is the International Normalized Ratio and it compared the patient's PT time to a reference range. The INR represents a "normalized" PT time test result that provides a workable reference range that all laboratories can report to monitor patients who are taking Coumadin.
-The normal INR for patients on Coumadin therapy is usually maintained between 2.0 and 3.0, the reference range mean is 12 seconds.
For patients who are not on anticoagulation therapy, 11 - 15 seconds is generally normal, but may vary by lab.

what is a plasma fibrinogen level and what do increased and decreased levels indicate?

-Fibrinogen is the major plasma protein coagulation factor.
-Low plasma fibrinogen is associated with an increased risk of bleeding due to impaired primary and secondary hemostasis
-high levels can indicate an inflammatory response, lead to increases in clot stiffness, increased resistance of the clot to fibrinolysis and increased blood viscosity

What is significant/different about each WBC type? What does an increased number of each WBC indicate? How do you calculate absolute leukocyte counts?

Granulocytes = Neutrophils, eosinophils, basophils (Your colored cells)
Phagocytes, along with monocytes
Agranulocytes = Monocytes and lymphocytes
Lymphocytes are immune responses