Page 2633 - Hematology_ Basic Principles and Practice ( PDFDrive )

e14 Part XIII Consultative Hematology

Platelet Aggregometry
Summary points • “Gold standard” for measuring platelet function
• Poor interlaboratory standardization of sample collection methods, agonists, agonist concentrations, parameters of
interest and other methodologic aspects can limit interpretability
• Test availability often limited to specialized hemostasis laboratories due to significant technical and quality control
requirements
Methodology Turbidometric or impedance
Specimen requirements Citrate
Indications Assessment of platelet function
Reference range Laboratory dependent; control specimen often required
Interpretation • Common agonists include ADP, arachidonic acid, collagen, epinephrine, ristocetin, thrombin; pattern of
aggregation and presence or absence of primary or secondary waves help to define certain rare, inherited but
well-characterized platelet function disorders (e.g., Glanzmann thrombasthenia, Bernard-Soulier syndrome)
• Other less specific abnormalities seen in acquired disorders: uremia, myeloproliferative neoplasms,
myelodysplastic syndromes, dysproteinemia, liver disease, cardiopulmonary bypass, drug effect
Related tests PFA-100, VerifyNow assay
Interfering substances Antiplatelet therapy and other drugs

ADP, Adenosine diphosphate.

SELECTED REFERENCE VALUES

TABLE Estimated Blood Volumes
162.1
Total Blood Volume (mL/kg)
a
Age Plasma Volume (mL/kg) Red Blood Cell Mass (mL/kg) From Plasma Volume From Red Blood Cell Mass
Newborn 41.3 43.1 82.1 86.1
46.0 78.0 84.7
1–7 days 51–54 37.9 82–86 77.8
1–12 months 46.1 25.5 78.1 72.8
1–3 years 44.4 24.9 73.8 69.1
47.2 81.8
4–6 years 48.5 25.5 80.0 67.5
49.6 85.6
7–9 years 52.2 24.3 87.6 67.5
49.0 86.1
10–12 years 51.9 26.3 87.6 67.4
46.2 83.2
13–15 years 51.2 88.3
16–18 years 50.1 90.2
Adults 39–50 20–35 68–88 55–75
a Red cell volume is approximately 5 mL/kg less in females compared with males.Reprinted by permission of the Society of Nuclear Medicine from Price DC, Ries C:
Appendix. In Handmaker H, Lowenstein JM, editors: Nuclear Medicine in Clinical Pediatrics, New York, 1975, Society of Nuclear Medicine, p 279. Red cell volume
reference from International Committee for Standardization in Haematology: Recommended methods for measurement of red-cell and plasma volume. J Nucl Med
21:793, 1980.