Tests and Principles Flashcards
IN what kind of solution is hemoglobin S insoluble that most other hemoglobins, including A, are? what reduces the released Hgb in the solution, and how does the Hgb escape?
concentrated phosphate solutions; hydrosulfite; a surfactant lyses the RBCs
What type of blood sample anticoagulant is used for the sickle solubility test?
EDTA preferred, others can be used: clotted specimens are unacceptable,
How long can a blood sample be stored at 2 to 8 C prior to Sickle cell solubility screening?
up to two weeks
The phosphate buffer used in the SS screening contains what preservative and how must it be handled for disposal>
sodium azide- flush with lots of water to prevent build up of explosive metal azides
What’s in the bottom of the SS screen tube?
sodium hydrosulfite
AT what temp should samples and reagents be for the sickle solubility screen? what else should be done before testing?
room temp; mix well
How does patient’s hemoglobin level affect sickle solubility testing?
If it is = 8 g/dL, add 100 uL sample
If higher, add only 50 uL sample
When Hb S is ________ it forms sickled cells due to elongated tactoids.
deoxyhemoglobin/ deoxygenated?
WHat are some blood disorders that can give false positive sickle solubility screens? How to resolve?
Multiple myeloma; cryoglobulinemia; other dysglobulinemias;
wash cells in normal saline then bring to normal volume with normal compatible plasma or serum
What type of hemoglobin can cause false positives in the sickle solubility screen and therefore what patients can’t be screened this way?
Hb F; under 6 mos old
WHat other types of variant hemoglobins can give a positive sickling rxn?
Hgb C Harlem or Georgetown
HOw is a positive sickle cell screen followed up?
hemoglobin electrophoresis
What does the ESR measure ?
the erythrocyte sedimentation rate, a nonspecific measure of inflammation
what is the ratio of blood to anticoagulant in the manual ESR? what is the anticoagulant? Is EDTA specimen acceptable ?
4 parts blood to 1 part sodium citrate; yes but must dilute with the citrate
Are controls for the ESR pos/neg or normal/abnormal?
normal/abnormal
How is ESR reported and what are normal ranges?
in mm/hr
males, 0 to 22 mm/hr
femlaes, 0 to 29 mm/hr
what is the reportable range of the sed rate?
0 to 150 mm/hr
what can cause an indistinct boundary between the red cells and plasma of an ESR?
red cell flocculation– in pt’s with a high sed rate this can make determination of true rate impossible
what kind of result may occur if the anticoagulant ration is too high in the ESR?
falsely elevated ESR
What is the LAP stain and score, and what does it differentiate?
Leukocyte alkaline phosphatase, scored by grading intensity and granule size in 100 neutrophils; Will be decreased in CML (and PNH) and increased in leukemoid reaction ( and PV, blast crisis, late pregnancy
what are peroxidase stains useful in diff’ing?
granulocytic cells contain peroxidase in their granules, and to a lesser extent monocytic cells do; however LYMPHOCYTIC series are NEGATIVE
Diffs AML from ALL blasts
What does the Schilling test evaluate?
IF deficiency or malabsorption of B12
If a patient has an abnormal part I Schilling test but a normal part II, what does this indicate and why?
the patient does not make IF which is the cause of the malabsorption, bc in part II If is added.
If part II is still abnormal there is another cause of malabsorption
what tests would be on an appropriate panel for a patient who has had several DVTs and is possibly in a hypercoagulative state?
Pt and aPTT for the baseline (see if there’s an inhibitor); Lupus anticoagulant test (a common cause of thrombosis); activated Protein C Resistance (APC) test; and d-dimer to ensure there is actually thrombosis occurring.
in what timeframe should a mixing study be done on a sample, then how stored if not performed?
4 hours; -70 up to 1 year
what hemoglobin migrates with S on cellulose, alkaline hemoglobin electrophoresis?
D and G
what is the order of migration of hemoglobins on cellulose alkaline electrophoresis from the application point? What migrates along with A2 and may need citrate acid agar ?
A2, C, E first ; S, D, G; F; A
Since C migrates with A2 you would need to clarify with citrate
