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Platelet Count and Tests of Platelet Function Core Lab Study

Synonym/Acronym

Thrombocytes.

Rationale

The platelet count is used to assist in diagnosing and evaluating treatment for blood disorders such as thrombocytosis and thrombocytopenia and to evaluate preprocedure or preoperative coagulation status; platelet function testing is used to assist in identification of inherited or acquired platelet dysfunction or to evaluate therapeutic response to platelet-inhibiting drugs. Tests of platelet function have largely replaced the bleeding time and clot retraction tests.

A small group of studies in this Manual have been identified as Core Lab Studies. The designation is meant to assist the reader in sorting the basic “always need to know” laboratory studies from the hundreds of other valuable studies found in the Manual—a way to begin putting it all together.

Normal, abnormal, or various combinations of core lab study results can indicate that all is well, reveal a problem that requires further investigation with additional testing, signal a positive response to treatment, or suggest that the health status is as expected for the associated situation and time frame.

Platelet count is part of a CBC, one of the most requested laboratory studies, and is included in the Anemia profile, Complete Blood Count, General Health panel, and Obstetric panel.

Patient Preparation

There are no food, fluid, activity, or medication restrictions unless by medical direction for platelet count. Regarding platelet function tests: Platelet inhibitor drugs will affect the results of platelet function testing. Patients who have been treated with inhibitor drugs should consult the laboratory for the appropriate time frames.

Normal Findings

Method: Automated, computerized, multichannel analyzers for platelet count; closure time endpoint for platelet function screening test; aggregometry for platelet aggregation studies; flow cytometry for evaluation of surface glycoprotein expression.

AgePlatelet Count*SI Units (Conventional Units × 1)MPV (fL)IPF (%)
Birth150–300 × 103/microL150–300 × 109/L8.1–12.21.6–7.1
6–23 mo200–450 × 103/microL200–450 × 103/microL8.1–12.21.7–4.8
2–5 yr150–400 × 103/microL150–400 × 103/microL8.1–12.21.3–3.9
6–17 yr150–450 × 103/microL150–450 × 103/microL8.1–12.21.3–6.7
Adult, older adult150–450 × 103/microL150–450 × 109/L8.1–12.21.1–11.1

Note: Platelet counts may decrease slightly with age.

*Conventional units.

MPV = mean platelet volume.

Care must be taken when reviewing platelet counts after a blood product transfusion—documentation should clearly reflect the time and date of the last transfusion with respect to the collection time of the study.
Summary: Tests of Platelet Function
Study TypeInterpretation of ResultsComments
Platelet Function-Closure Time (screening test)Normal Closure Time: variable, based on agonist and method, e.g., Collagen/ADP 60–130 sec by one method and 77–133 sec by another; Collagen/Epinephrine 80–180 sec by one method and 98–185 sec for anotherThe screening test is used to identify abnormal bleeding tendency. Closure times can be used to distinguish between acquired (e.g., inhibitory drugs) and hereditary platelet defects
ADP = adenosine diphosphate
Summary Tests of Platelet Function: Aggregation Studies
Normal Platelet Aggregation and ATP Release Range (varies by laboratory/method): Two representative examples
AgonistExample #1 Aggregation (%)Example #1 ATP Release (nmol)Example #2 Aggregation (%)Example #2 ATP Release (nmol)
ADP45–940.19–1.4567–97Less than 2.15
Arachidonic42–790.04–1.172–94Less than 1.27
Collagen52–880.44–1.6875–930.85–2.85
Epinephrine48–93Greater than 0.5267–880.19–2.63
Ristocetin (High)30–100N/A73–104N/A
Ristocetin (Low)Less than 5N/AN/AN/A
Platelet aggregation testing often requires a coagulation consult with a pathologist prior to scheduling specimen collection. The consultation includes completion of a patient history form, specifically detailing patient/family history of abnormal bleeding, and the patient’s complete medication history. Normal aggregation response varies by agonist and method. (Note: abnormal aggregation results may include interpretation by a pathologist.)
Summary Continued Tests of Platelet Function: Flow Cytometry
Study TypeInterpretation of ResultsComments
Platelet surface glycoprotein (GP) receptor expression. Common receptors marked for evaluation include GPIa (CD49b); GPIb (CD42b); GPIIb (CD41); GPIIIa (CD61); GPVI (CD-NA); GPIX (CD42a)Platelet surface glycoprotein expression = Normal (Some laboratories report Greater Than or Equal to 70.0%) Abnormal findings may be supplemented with an interpretation by a pathologist.Flow cytometry is used to identify hereditary platelet disorders by known patterns of significantly decreased receptor expression, e.g., low levels of GPIIb and GPIIIa expression are associated with Glanzmann’s thrombasthenia; low levels of GPIX and GPIb are associated with Bernard-Soulier syndrome
Note: platelet receptors can also be evaluated using electron microscopy.
Tests to Evaluate the Effectiveness of Antiplatelet Therapy
Study TypeInterpretation of ResultsComments
VerifyNow® Platelet Reactivity to AspirinMeasured in Aspirin Reactivity Units (ARU): Less than 550 ARU = consistent with aspirin-induced inhibition of platelet function; Greater than or equal to 550 ARU = platelet dysfunction related to aspirin has not been detectedIdentifies platelet dysfunction due to the effects of aspirin
Verify Now® P2Y12 Inhibitors (e.g., clopidogrel (Plavix), prasugrel (Effient), ticagrelor (Brilinta), and ticlopidine (Ticlid).Measured in Platelet Reactivity Units (PRU): Baseline (prior to start of drug administration): 194–418 PRU Therapeutic Effect: Less than 194 PRURecommendations for special circumstances:
  • Long-term clopidogrel therapy Equal to or Less than 180 PRU = adequate response
  • Equal to or Greater than 208 PRU with pending cardiac surgery = may proceed
  • Less than 208 PRU with pending surgery = delay and retest in 12–24 hr

Results should be interpreted with other available clinical and laboratory information.

Critical Findings and Potential Interventions

Platelet Count

Consideration may be given to verifying the critical findings before action is taken. Policies vary among facilities and may include requesting immediate recollection and retesting by the laboratory.

Critically low platelet counts can lead to brain bleeds or gastrointestinal hemorrhage, which can be fatal. Some signs and symptoms of decreased platelet count include spontaneous nosebleeds or bleeding from the gums, bruising easily, petechiae, prolonged bleeding from minor cuts and scrapes, heavy or prolonged menstrual bleeding, and bloody urine or stool. Possible interventions for decreased platelet count may include transfusion of platelets or changes in anticoagulant therapy.

An IgA deficiency-mediated platelet transfusion reaction usually occurs within 1 hour of transfusion. A reaction does not occur in all patients with an IgA deficiency and can occur along a spectrum ranging from no symptoms or adverse reaction to full-blown, life-threatening anaphylaxis. (See study titled “Blood Typing, Antibody Screen, and Crossmatch Core Lab Study” for information regarding transfusion reactions.)

Overview

Study type: Blood collected in a lavender-top [EDTA] tube for platelet count; lavender-top [EDTA] or blue-top [3.2% sodium citrate] tube for platelet function test by aggregrometry; lavender-top [EDTA], pink-top [K2EDTA] or yellow-top [ACD Solution B] tube for platelet receptor flow cytometry. The laboratory should be consulted regarding recommended collection containers and order of draw when multiple tubes will be drawn with platelet function studies; related body system: Circulatory/Hematopoietic and Immune systems. For the platelet count: the specimen should be mixed gently by inverting the tube 10 times. The specimen should be analyzed within 24 hr when stored at room temperature or within 48 hr if stored at refrigerated temperature. If it is anticipated the specimen will not be analyzed within 24 hr, two blood smears should be made immediately after the venipuncture and submitted with the blood sample. For platelet function studies: the laboratory should be consulted prior to specimen collection for special instructions regarding specimen stability and transportation instructions.

What Are Platelets and Why Are They Important?

Platelets are nonnucleated, cytoplasmic, round or oval disks formed by budding off of large, multinucleated cells (megakaryocytes) that move throughout the body via the circulatory system. Platelets have an essential function in coagulation, hemostasis, and blood thrombus formation. The three stages in the process of primary hemostasis include the three “A”s:

Coagulation must be localized to the site of vessel wall injury, or the growing platelet plug would eventually occlude the affected vessel. In tertiary hemostasis the fibrinolytic system, under normal circumstances, begins to work once fibrin begins to form, to ensure coagulation is limited to the appropriate site. For additional information related to activation of the fibrinolytic system, refer to the studies titled “D-Dimer,” “Fibrinogen Degradation Products,” “Plasminogen and Tissue Plasminogen Activator Antigen,” and “Protein C and Protein S.”

Evaluating Platelet Count

Thrombopoiesis or platelet production is reflected by the measurement of the immature platelet fraction (IPF). This parameter can be correlated to the total platelet count in the investigation of platelet disorders. A low platelet count with a low IPF can indicate a disorder of platelet production (e.g., drug toxicity, aplastic anemia, or bone marrow failure of another cause), whereas a low platelet count with an increased IPF might indicate platelet destruction or abnormally high platelet consumption (e.g., mechanical destruction, disseminated intravascular coagulation, idiopathic thrombocytopenic purpura [ITP], thrombotic thrombocytopenic purpura).

Thrombocytosis is an increase in platelet count. In reactive thrombocytosis, the increase is transient and short-lived, and it usually does not pose a health risk. One exception may be reactive thrombocytosis occurring after coronary bypass surgery. This circumstance has been identified as an important risk factor for postoperative infarction and thrombosis. The term thrombocythemia describes platelet increases associated with chronic myeloproliferative disorders.

Thrombocytopenia describes platelet counts of less than 140 × 103/microL. Decreased platelet counts occur whenever the body’s need for platelets exceeds the rate of platelet production; this circumstance will arise if production rate decreases or platelet loss increases. Platelet counts may also be decreased in the presence of autoantibodies as seen in refractoriness to platelet transfusions, posttransfusion purpura, or neonatal alloimmune thrombocytopenia. For additional information regarding platelet antibodies, refer to the study titled, “Platelet Antibodies.” The severity of bleeding is related to platelet count as well as platelet function. Platelet counts can be within normal limits, but the patient may exhibit signs of internal bleeding; this circumstance usually indicates an anomaly in platelet function.

When abnormal platelet findings are flagged by an automated cell counter, the situation must be investigated; this usually begins with a review of a peripheral blood smear or a platelet estimate. Abnormally large or giant platelets may result in underestimation of automated counts by 30% to 50%. Giant platelets can be as large as a normal red blood cell (RBC). A normal RBC is 7–88 micrometers, and a normal platelet is 1.5–3 micrometers. Giant platelets are associated with relatively rare platelet disorders, e.g., inherited disorders such as Bernard-Soulier and May-Hegglin or a condition known as immune thrombocytopenia (previously referred to as immune thrombocytopenic purpura). Underestimation of the platelet count may also be caused by platelet clumping, which can be caused by a traumatic venipuncture or the presence of EDTA-dependent antibodies that interfere with GP IIb/IIIa platelet receptors. In both cases, the problem may be solved by recollecting the specimen. Additionally, in the case of clumping, the re-draw should be performed using a collection container with a different anticoagulant, e.g., sodium citrate (blue top). The laboratory’s platelet estimate procedure may include a mathematical calculation to approximate the platelet count from a platelet estimate as well as making an assessment of platelet characteristics that indicate a normal review:

The platelet count may also be affected by administration of heparin that is associated with two types of thrombocytopenia: Type I heparin-induced thrombocytopenia (HIT) is believed to occur as the result of an interaction between heparin and circulating platelets. Type I HIT causes a mild thrombocytopenia soon after administration of heparin, usually occurs in patients who have not been previously received heparin, and resolves in a few days whether the heparin therapy continues or is stopped. Type II HIT, believed to be the result of an immune-mediated response, also occurs in patients who have not been previously treated with heparin, begins later than type I HIT unless the patient is sensitized from a previous exposure, and can result in a 50% or greater decrease in platelet count. Functional assays for HIT II antibodies are available but not routinely requested. The risk of thrombosis is high with type II HIT, and administration of heparin should be stopped in patients who develop type II HIT.

Evaluating Platelet Size and Shape

Platelet size, reflected by mean platelet volume (MPV), and cellular age are inversely related; that is, younger platelets tend to be larger. An increase in MPV indicates an increase in platelet turnover. Therefore, in a healthy patient, the platelet count and MPV have an inverse relationship. Abnormal platelet size may also indicate the presence of a disorder. MPV and platelet distribution width are both increased in ITP. MPV is also increased in May-Hegglin anomaly, Bernard-Soulier syndrome, myeloproliferative disorders, hyperthyroidism, and pre-eclampsia. MPV is decreased in Wiskott-Aldrich syndrome, septic thrombocytopenia, and hypersplenism. Platelet size and shape may be evaluated by manually performing a “platelet estimate” as described in the previous section subtitled, “Evaluating Platelet Count.”

Platelet Function Tests

Platelet dysfunction can be inherited or acquired. Common causes of acquired platelet dysfunction include medications such as aspirin, clopidogrel, and nonsteroidal anti-inflammatory drugs or systemic disorders such as myeloproliferative neoplasms, systemic lupus erythematosus, and uremia. A combination of tests that evaluate platelet function (adhesion, aggregation, flow cytometry) and genetic testing can be used to identify the presence and type of dysfunction and to differentiate between inherited and acquired dysfunction. The bleeding time and clot retraction tests have largely been replaced by

A variety of laboratory methods and specimen types are employed to evaluate platelet aggregation; some methods require platelet-rich plasma, while others are performed using whole blood specimens. Many of the aggregation systems use natural platelet agonists and high shear flow conditions to simulate the normal physiological environment of circulating platelets. Platelet aggregation can be measured in a patient specimen by “time to closure” or from aggregometers using optical or impedance detection:

Tests That Measure Response to Therapeutics, e.g., Aspirin, P2Y12 Inhibitors, and Glycoprotein (GP) IIb/IIIa Inhibitors

Antiplatelet drugs prevent platelets from clumping and forming clots. These tests are mainly used to identify patients who are nonresponders to drug therapy and therefore may not be good candidates to undertake a specific or combined approach to antiplatelet therapy. The use of platelet function testing to guide the dosing or withdrawal (e.g., establishing time frames for withholding before surgery) of therapeutics is not generally recommended at this time by the American Heart Association (AHA) or the Choosing Wisely Campaign (an initiative of the American Board of Internal Medicine Foundation) due to the lack of strongly supportive data that clearly identify its clinical utility in this regard. According to current AHA guidelines, platelet function testing may be considered for guidance on the timing of cardiac surgery in some patients (e.g., those who have recently received P2Y12 receptor inhibitors or who have ongoing dual antiplatelet therapy). There are current AHA recommendations for the timing of withdrawal from aspirin; guidelines may vary by provider and facility.

Currently, there are three classes of antiplatelet agents: aspirin (acetylsalicylic acid), P2Y12 inhibitors, and GP IIb/IIIa inhibitors.

Aspirin blocks production of thromboxane A2, thereby blocking platelet aggregation. The test uses an agonist to activate platelets in the patient sample. Platelet function is measured by the amount of activated platelet GP IIb/IIIa receptors that bind to fibrinogen-coated microparticles. If aspirin has had the expected antiplatelet effect, aggregation will be reduced.

Thienopyridines are a class of P2Y12 inhibitors (e.g., clopidrogrel [Plavix]), prasugrel (Effient), ticlopidine (Ticlid), and ticagrelor (Brilinta®) whose antiplatelet effect is achieved by inhibiting ADP-mediated platelet activation. P2Y12 inhibitors irreversibly inhibit the binding of ADP to the P2Y12 receptor on the platelet surface, which has the effect of also disrupting platelet degranulation and inhibiting other receptors down the line.

The GP IIb/IIIa inhibitors block platelet aggregation by preventing fibrinogen and vWF from binding to the IIb/IIIa platelet receptor, which disrupts the eventual formation of a stable clot.

Genetic Testing

Genetic test methods to identify drug-related defects in platelet function are mainly used to identify patients who are nonresponders to drug therapy and therefore may not be good candidates to undertake a specific or combined approach to antiplatelet therapy. The use of genetic testing to guide the dosing of antiplatelet therapeutics is not recommended at this time by the American Heart Association (AHA) or the Choosing Wisely Campaign due to the lack of strongly supportive data that clearly identify its clinical utility in this regard.

Next-generation sequencing is used to identify more than 30 genetic variants associated with significant defects in platelet function. Drugs such as clopidogrel (Plavix), abciximab (ReoPro), eptifibatide (Integrilin), and tirofiban block platelet receptor sites and inhibit platelet function. Aspirin also can affect platelet function by the irreversible inactivation of a crucial cyclooxygenase enzyme. Medications such as clopidogrel and aspirin are prescribed to prevent heart attack, stroke, and blockage of coronary stents. Studies have confirmed that up to 30% of patients receiving these medications may be nonresponsive.

The metabolism of many commonly prescribed medications is driven by the cytochrome P450 (CYP450) family of enzymes. Genetic variants can alter enzymatic activity that results in a spectrum of effects ranging from the total absence of drug metabolism to ultrafast metabolism. Impaired drug metabolism can prevent the intended therapeutic effect or even lead to serious adverse drug reactions. Poor metabolizers are at increased risk for drug-induced adverse effects due to accumulation of drug in the blood, while ultra-rapid metabolizers require a higher than normal dosage because the drug is metabolized over a shorter duration than intended. Other genetic phenotypes used to report CYP450 results are intermediate metabolizer and extensive metabolizer. CYP2C19 is a gene in the CYP450 family that metabolizes drugs such as clopidogrel. Genetic testing can be performed on blood samples submitted to a laboratory. Testing for the most common genetic variants of CYP2C19 is used to predict altered enzyme activity and anticipate the most effective therapeutic plan. The test method commonly used is polymerase chain reaction. Counseling and informed written consent are generally required for genetic testing.

Knowledge of genetics assists in identifying those who may benefit from additional education, risk assessment, and counseling. Genetics is the study and identification of genes, genetic mutations, and inheritance. For example, genetics provides some insight into the likelihood of inheriting a tendency to abnormally metabolize drugs. Some conditions are the result of mutations involving a single gene, whereas other conditions may involve multiple genes and/or multiple chromosomes. Further information regarding inheritance of genes can be found in the study titled “Genetic Testing.”

Platelet Transfusion Reaction—Related to the Therapeutic Use of Platelets in Some IgA-Deficient Individuals

IgA is primarily involved in immune health maintenance of the mucosa that lines the gastrointestinal, genitourinary, and respiratory systems. IgA deficiency is the most common deficiency of the five main immunoglobulin classes (IgA, IgD, IgE, IgG, and IgM). An IgA deficiency-mediated transfusion reaction is a relatively rare type of anaphylaxis. It has been observed when an IgA-deficient recipient is transfused with a platelet product containing anti-IgA antibodies. The reaction usually occurs within 1 hour of transfusion. A reaction does not occur in all patients with an IgA deficiency and can occur along a spectrum ranging from no symptoms or adverse reaction to full-blown, life-threatening anaphylaxis. Commonly transfused blood products, such as platelets, contain small amounts of plasma. Antibodies to IgA and other immunoglobulins are present in the plasma unless they are sourced from

Indications

Platelet Count

Platelet Function Tests

Interfering Factors

Factors That May Alter the Results of the Study

Platelet Count

  • Drugs and other substances that may decrease platelet counts include acetophenazine, amphotericin B, azathioprine, butaperazine, chlorophenothane, dactinomycin, dextromethorphan, diuretics (furosemide, thiazides), estrogens, gold salts, heparin, hydroxychloroquine, iproniazid, linezolid, mefenamic acid, miconazole, mitomycin, nitrofurantoin, novobiocin, nystatin, penicillin, plicamycin, procarbazine, pyrazolones, quinidine, quinine, ranitidine, streptomycin, sulfonamides, tetracycline, thiabendazole, thiouracil, tolazoline, tolbutamide, trifluoperazine, and valproic acid.
  • Drugs and other substances that may increase platelet counts include estrogens and glucocorticoids.
  • X-ray therapy may also decrease platelet counts.
  • The results of blood counts may vary depending on the patient’s position. Platelet counts can decrease when the patient is recumbent, as a result of hemodilution, and can increase when the patient rises, as a result of hemoconcentration.
  • Platelet counts normally increase under a variety of stressors, such as high altitudes or strenuous exercise.
  • Platelet counts are normally decreased before menstruation and during pregnancy.

Other Considerations

  • Leaving the tourniquet in place for longer than 60 sec can affect the results.
  • Traumatic venipunctures may lead to erroneous results as a result of activation of the coagulation sequence.
  • Failure to fill the tube sufficiently (i.e., tube less than three-quarters full) may yield inadequate sample volume for automated analyzers and may be a reason for specimen rejection.
  • Hemolysis or clotted specimens are reasons for rejection.
  • CBC should be carefully evaluated after transfusion or acute blood loss because the value may appear to be normal.

Platelet Function Tests

  • Drugs such as NSAIDs will interfere with the aspirin study. Direct P2Y12 and IIb/IIIa inhibitors will interfere with all types of platelet function tests, and testing must not be performed until advised by the testing laboratory.
  • Drugs and other substances that may decrease platelet function include antibiotics, antidepressants, antihistamines, blood thinners (e.g., warfarin).
  • Elevated Hct (e.g., greater than 55%) or platelet counts less than 50,000–100,000 may produce invalid results.

Potential Medical Diagnosis: Clinical Significance of Results

Platelet Count

Increased In

Conditions that involve inflammation activate and increase the number of circulating platelets:

  • Acute infections
  • After exercise (transient)
  • Anemias (posthemorrhagic, hemolytic, iron deficiency) (bone marrow response to anemia; platelet formation is unaffected by iron deficiency)
  • Cirrhosis
  • Essential thrombocythemia
  • Leukemias (chronic)
  • Malignancies (cancer, Hodgkin’s, lymphomas)
  • Pancreatitis (chronic)
  • Polycythemia vera (hyperplastic bone marrow response in all cell lines)
  • Rebound recovery from thrombocytopenia (initial response)
  • Rheumatic fever (acute)
  • Rheumatoid arthritis
  • Splenectomy (2 mo postprocedure) (normal function of the spleen is to cull aging cells from the blood; without the spleen, the count increases)
  • Surgery (2 wk postprocedure)
  • Trauma
  • Tuberculosis
  • Ulcerative colitis

Platelet Function:

  • N/A

Decreased In

Platelet Count

Conditions that are a result of megakaryocytic hypoproliferation:

Platelet Function

Acquired

  • Bone marrow disorders or diseases (e.g., chronic myelogenous leukemia, multiple myeloma, polycythemia vera, primary myelofibrosis, primary thrombocythemia, thrombotic thrombocytopenic purpura)
  • Glanzmann thrombasthenia (a rare disorder associated with lymphoproliferative and autoimmune diseases and related to deficient or inhibited GpIIb/IIIa signaling, often autoimmune in nature. Can also be inherited. Platelets are usually normal in size and number.)
  • Immune thrombocytopenia (bleeding disorder in which the immune system destroys platelets)
  • Kidney disease(especially end-stage kidney failure)
  • Liver disease (e.g., cirrhosis)
  • Medications
  • Pre-eclampsia (related to HELLP syndrome or to high blood pressure in pregnancy)
  • Systemic lupus erythematosus (related to autoantibodies)
  • Uremia (related to impaired interactions between the platelets and damaged vessel wall and partially due to uremic toxins)
  • von Willibrand disease (can be acquired or inherited)

    Inherited

  • Bernard-Soulier syndrome (related to a rare condition [autosomal recessive pattern] where one of three mutations affects formation of the GPIb-IX-V complex. Platelet count is decreased, and platelets are large.)
  • Chediak-Higashi anomaly or syndrome (rare autosomal recessive disorder, usually diagnosed in childhood, characterized by partial oculocutaneous albinism [i.e., affecting pigment deposition in the skin and eyes]. Patients have an increased susceptibility to infection, as well as typical signs of platelet dysfunction such as tendency to bruise and bleed easily. Platelets are normal in size and number.)
  • Glanzmann thrombasthenia (related to a rare condition [autosomal recessive pattern] that results in abnormal platelet aggregation due to the inability to form platelet glycoprotein GPIIb/IIIa. Platelets are usually normal in size and number.)
  • Gray platelet syndrome(rare condition that can be inherited as an autosomal recessive or autosomal dominant pattern. The platelets degranulate when collected in EDTA anticoagulated tubes and appear gray in color when stained on a peripheral blood smear and platelet count is decreased.)
  • Hemophilia; two types (related to an X-linked recessive disorder, either hemophilia A [Factor VIII deficiency] or hemophilia B [Factor IX deficiency or Christmas disease])
  • Hermansky-Pudlak syndrome (rare autosomal recessive disorder, characterized by oculocutaneous albinism [i.e., affecting pigment deposition in the skin and eyes], increased susceptibility to infection, and typical signs of platelet dysfunction as seen in Chediak-Higashi anomaly. There are a number of subtypes. Platelets are normal in size and number.)
  • MYH9-related disorders: May-Hegglin anomaly, Epstein syndrome, Fechtner syndrome, and Sebastian syndrome (related to mutations of the MYH9 gene that codes for proteins required in normal development of cell shape and movement. Related disorders are characterized by thrombocytopenia and giant platelets from birth as well as hearing loss in infancy, premature development of cataracts, and early-onset kidney disease.)
  • von Willibrand disease (can be acquired or inherited [inheritance pattern for type I and type II is autosomal dominant; for type III autosomal recessive])
  • Wiskott-Aldrich syndrome (syndrome of immunodeficiency and dysfunctional platelets characterized by decreased platelet count, very small platelets [most platelet function disorders have normal to large platelets], and neutropenia)

Nursing Implications, Nursing Process, Clinical Judgement

Potential Nursing Problems: Assessment & Nursing Diagnosis

ProblemsSigns and Symptoms
Bleeding (related to increased destruction, loss, or consumption)Altered level of consciousness; hypotension; increased heart rate; decreased Hgb, Hct, platelet count; capillary refill greater than 3 sec; cool extremities; shortness of breath
Confusion (related to decreased tissue perfusion secondary to platelet clumping and altered blood flow)Disorganized thinking; restlessness; irritability; altered concentration and attention span; changeable mental function over the day; hallucinations; inability to follow directions; disoriented to person, place, time, and purpose; inappropriate affect
Pain (related to joint disturbances associated with bleeding, bleeding into the tissues)Expression of pain, facial grimace, moaning, crying, report of pain
Protection (related to decreased platelet count, bleeding risk)Ease of bruising; blood in urine, stool, sputum; nosebleed; bleeding gums; presence of hematoma or petechiae; headache; vision changes
Tissue perfusion (inadequate—related to altered blood flow associated with platelet clumping)Confusion, altered mental status, headache, dizziness, visual disturbances, hypotension, cool extremities, capillary refill greater than 3 sec, weak pedal pulses, altered level of consciousness, decreased urine output

Before the Study: Planning and Implementation

Teaching the Patient What to Expect

  • Discuss how this test can assist in diagnosing, evaluating, and monitoring bleeding disorders.
  • Explain that a blood sample is needed for the test.

After the Study: Implementation & Evaluation Potential Nursing Actions

Avoiding Complications

  • Transfusion reaction may occur in some patients. Transfusion reaction is a critical finding.

Treatment Considerations

Bleeding

  • CBC results should be carefully evaluated during transfusion or acute blood loss because the body is not in a state of homeostasis, and values may be misleading.
  • Considerations for draw times after transfusion include the type of product, the amount of product transfused, and the patient’s clinical situation.
  • Generally, specimens collected an hour after transfusion will provide an acceptable reflection of the effects of the transfused product.
  • Measurements taken during a massive transfusion are an exception, providing essential guidance for therapeutic decisions (e.g., selection of blood products) during critical care.

Confusion

  • Treat the medical condition that may be responsible for the confusion.
  • Monitor and trend platelet count.
  • Evaluate medications as a causative factor.
  • Prevent falls and injury through appropriate use of postural support, bed alarm, one-to-one interventions, or appropriate restraints.
  • Administer prescribed medications (IV immunoglobulin, recombinant interleukin).

Pain

  • Assess level of pain and identify pain characteristics, what makes it better or worse.
  • Administer prescribed analgesics, assess effectiveness, and collaborate with HCP to provide adequate pain management.

Tissue Perfusion

  • Facilitate management of inadequate tissue perfusion.
  • Monitor blood pressure, and dizziness.
  • Check skin temperature for warmth, assess capillary refill, assess pedal pulses, and monitor level of consciousness.
  • Verify urine output to be in excess of 30 mL/hr and ensure adequate fluid intake or administer IV fluids as ordered.

Safety Considerations

Protection

  • Assess for bruising, petechiae, or hematoma.
  • Monitor and trend platelet count.
  • Administer platelets or other blood products.
  • Administer ordered stool softeners or corticosteroids.
  • Monitor and trend vital signs and report significant variances.
  • Monitor stool, urine, sputum, gums, and nose for blood.
  • Coordinate laboratory draws to decrease frequency of venipuncture.
  • Institute bleeding precautions, avoid intramuscular (IM) injections, prevent trauma, be gentle with oral care and suctioning, and avoid use of a sharp razor.
  • Administer prescribed medications.

Nutritional Considerations

  • Advise consuming a variety of foods within the basic food groups, maintain a healthy weight, be physically active, limit salt intake, limit alcohol intake, and avoid the use of tobacco.

Clinical Judgement

  • Consider how to address cultural and religious barriers to the administration of blood and blood products.

Follow-Up and Desired Outcomes

  • Acknowledges the importance of taking precautions against bruising and bleeding, including the use of a soft-bristle toothbrush, use of an electric razor, avoidance of constipation to prevent straining while having a bowel movement, avoidance of acetylsalicylic acid and similar products, and avoidance of IM injections.
  • Recognizes the importance of periodic laboratory testing if taking an anticoagulant.
  • Adheres to the request to refrain from participating in at-risk activities that could cause trauma and bleeding.