Identifying Information and Courses from MediaLab, Inc.

Reaction PhaseLook at the phase in which reactions are occuring and see if the results match the reaction patterns on your panel. Reactions occurring only at immediate spin phase could indicate a possible IgM antibody, cold agglutinin, or rouleaux. Reactions occurring in the AHG phase could indicate a possible IgG antibody. Reactions occurring in both reaction phases could indicate a combination of both IgM and IgG antibodies or a strong IgM antibody that carries through to AHG phase. If a tube method is used, reactions are usually read at immediate spin and AHG phase. If a gel method is used, reaction readings are done only at AHG phase. PatternComparing the pattern of reactivity of the sample reactions with that of the panel cells will help to determine which antibody or antibodies are present. If the reactions match, or closely match, a specific panel cell, that could be the antibody.The strength of the reaction does not correlate with the clinical significance of the antibody present. It does correlate to the amount of antibody that is available to react. If reactions are strong at immediate spin (IS) phase and get weaker at antihuman globulin (AHG) phase, it is possible that a strong IgM antibody is present that is carrying through to the AHG phase (e.g., 4+ at IS and 1+ at AHG).The presence of multiple antibodies should be considered if reactions vary in strength or there are two separate reaction patterns in the IS and AHG phases.

All white cells present in a cerebrospinal fluid must be identified. If more than 10 cells/mm3 are present or there is difficulty identifying the few cells that are present, make a cytospin, a filtration, or a sedimentation preparation, stain with Wright-Giemsa, and perform differential count. Cytospins made with a cytocentrifuge are preferred since they are easiest to make and interpret, but filtration and sedimentation methods can also be used to prepare a slide for subsequent staining.

Smith KR, Fisher HC III, Hook, EW III: Prevalence of fluorescent monoclonal antibody-nonreactive Neisseria gonorrhoeae in five North American sexually transmitted disease clinics.J Clin Microbiol 34:1551-1552, 1996We compared a direct fluorescent monoclonal antibody (DFA) test with alternative enzymatic and fermention tests for identifying presumptive gonococcal isolates in a systematic sample from patients attending five sexually transmitted disease clinics in five cities.Fourteen (2.5%) of 556 isolates from three clinics were nonreactive with the DFA confirmatory reagent and reactive by both the Quad-Ferm and Rapid NH tests. The prevalence of DFA-nonreactive Neisseria gonorrhoeae isolates varies geographically and is independent of local methods for the identification of possible gonococci.On the basis of our findings, we recommend that for use in medicolegal and other instances in which a diagnosis of gonorrhea has the potential to have far-reaching effects, it is appropriate to test DFA reagent-nonreactive, oxidase-positive, gram-negative diplococci by alternative methods of gonococcal confirmation.Although the prevalence of such isolates could change, the fluorescent monoclonal antibody confirmation reagents remain useful for many clinical situations. Their ease of use and ready applicability for screening large numbers of isolates make them useful for many laboratories.

In addition to hereditary hemochromatosis (HH), there are other conditions of iron overload that must be considered in a differential diagnosis. Disorders such as sickle cell disease, thalassemia, sideroblastic anemia, congenital dyserythropoietic anemia, and liver disease may also cause iron overload. Transfusion-dependant patients and persons who abuse iron-containing vitamin supplements are also at risk. These conditions are usually described as secondary iron overload, in contrast to the primary iron overload of HH.Patient history, clinical signs and symptoms, biochemical and hematologic laboratory analyses, and possibly results of a liver biopsy may be needed to establish a diagnosis of a condition causing secondary iron overload. DNA tests for common HFE mutations are very likely the most important diagnostic tool for identifying HH as the cause of iron overload. In some patients, both secondary causes and HH may be contributing to iron overload. Differentiating the secondary causes of iron overload from HH is heavily dependent on the results of laboratory assays, but a complete discussion is beyond the scope of this course.

The ultimate goal in measuring CYP450 function or identifying polymorphisms is to predict effective therapeutic doses and responses in patients.Polymorphisms are identified using molecular techniques (allele-specific PCR, restriction digests, sequencing, hybridization assays, bead-based systems, microarrays, pyrosequencing, et al).Although most clinical labs do not offer PGx testing, reference labs are beginning to market these tests. For example, one reference laboratory in the Midwest that offers CYP2D6 profiling measures about one dozen of the most common and significant mutation sites on this enzyme. This allows for detection of approximately 98% of the known CYP2D6 polymorphisms. The laboratory then generates a report which will advise the physician on the patient's drug-metabolizing status.Estimates show that 6-10% of the general population have a complete deficiency of CYP2D6, with the prevalence of mutations varying from <1% to as much as 21% within a given population.

Bobby Jones, a phlebotomist at Georgetown Hospital, entered the room of Mrs. Mary Grayson with a physician's order to draw some blood work. After properly greeting Mrs. Grayson, identifying himself and checking her armband, Bobby prepared for the venipuncture. He suddenly notice a sign posted above the bed that read: “Restricted left arm usage. Previous mastectomy - Do no use left arm for venipuncture.” Bobby set up his equipment to use her right arm and noticed an IV line in Mrs. Grayson’s right arm positioned in a vein slightly above her wrist on the dorsum (top) of her forearm.

Red cell morphology can be defined as the appearance of the erythrocytes on a Wright's stained smear.Careful examination of the red cells for the purpose of identifying abnormalities is part of the differential procedure. This examination is important because it may provide valuable diagnostic information to the physician, as well as provide a quality control mechanism to verify red cell indices values as determined by automated or manual methods.Evaluating red cell morphology involves differentiating normal morphology from abnormal and artificial morphology. The abnormal morphology covered in this unit may be seen in a variety of disorders.

In order to prevent errors that affect specimen quality, the phlebotomist must pay close attention to detail during the entire venipuncture process. All steps of the phlebotomy procedure must be included for every venipuncture. This will help to maintain specimen integrity during the collection, transport, and handling of blood specimensProperly identify the patient every timeThe phlebotomist is responsible for correctly identifying the patient using two unique patient identifiers that include the patient's complete first and last name, medical record or hospital number, and/or date of birth. The patient location or room number, bed tag and chart are not reliable forms of identification and should not be used for patient identification. Every patient must verbalize his/her name to the phlebotomist, if able to do so. It is unacceptable for the phlebotomist to ask the patient to confirm his/her name that was verbalized by the phlebotomist. For example, the phlebotomist should say, "Would you please tell me (or spell) your name and birthdate. " The phlebotomist should NOT say, "Are you Sally Brown, and is your birthdate June 1, 1925?" If this is a hospital inpatient, check the information on the patient's wristband and confirm that the name and hospital number or medical record number matches the patient information on the test order. Never rely on identification attached to a bed, chart or door. NEVER draw a patient whose identity is not established or is in conflict. If there is a discrepancy, the phlebotomist must STOP and seek assistance to have the discrepancy resolved before proceeding with the venipuncture. If this is an outpatient that does not have a wristband, ask the patient (or guardian/caregiver) to state the patient's date of birth. A picture ID, such as a driver's license, can also be used for positive patient identification.

To improve the quality of conclusions when identifying antibodies, a checklist is a simple quality control tool to increase transfusion safety. If a specific antibody pattern cannot be identified with acceptable confidence, or if significant serologic or non-serologic data are inconsistent and cannot be rationalized, further testing will be required.Before concluding that the investigation is complete, unless not applicable, mentally reply to each question in the checklist. If any answer is no, has it been resolved? Antibody Identification Checklist Yes/No/NA 1. For a single antibody, does the reaction pattern fit only one antibody specificity? 2. Is antibody specificity consistent with the results of the initial antibody screen? 3. Are reaction phases consistent with antibody specificity? 4. If multiple antibodies are present, can all reactions be explained by the antibody combination? 5. If the autocontrol is negative, are patient red cells negative for the corresponding antigen(s)? 6. Have additional possible antibodies been excluded by selected red cells? 7. Can all variable reaction strengths be explained? 8. If tested, are antigen-negative donor cells compatible by antiglobulin crossmatch? 9. If there are data that do not fit antibody specificity or if there are results that are improbable, are they explainable? 10. Have all results and conclusions been systematically evaluated for consistency?