Laboratory Suggestions The Platelet Function Profile A New Format for Recording Platelet Function Tests PAMELA ROPER, PH.D., AND EMIL J. FREIREICH, M.D.

MANY CANCER PATIENTS experience transient thrombocytopenia as a result of the myelosuppressive effects of intensive antitumor therapy. Improved management of supportive care for these individuals has involved thorough characterization of platelet functional characteristics, as well as the monitoring of daily platelet counts. In the Department of Developmental Therapeutics at M. D. Anderson Hospital we are in the process of evaluating a multitest profile, which is performed serially on blood samples obtained at various stages of myelosuppression and recovery. These tests are expressed as a "platelet function profile" that details the following results: platelet count, platelet retention, platelet aggregation, platelet factor 3 availability, bleeding time, platelet volume distribution profiles, and capillary fragility. Description and Use The platelet function profile is composed of a series of linear scales that display ranges of values for each test (Fig. 1). Included in the profile are normal ranges Received December 27, 1977; received revised manuscript and accepted for publication February 22, 1978. Supported in part by grant CA 10376, awarded by the National Cancer Institute, DHEW, and Grant 1N65 from the N1H Grant RR5511. Address reprint requests to Dr. Roper: Department of Developmental Therapeutics, The University of Texas System Cancer Center, M. D. Anderson Hospital and Tumor Institute, 6723 Bertner Avenue, Houston, Texas 77030.

Department of Developmental Therapeutics, The University of Texas System Cancer Center, M. D. Anderson Hospital and Tumor Institute, Houston, Texas

(depicted by shaded areas). The designated tests are performed, and the results are recorded as follows: 1. Platelet counts are performed using the Technicon Autocounter system according to the method described by Brittin and associates. 1 2. Platelet retention is determined by a technic modified from that of Salzman. 6 The platelet count of native whole blood filtered through glass bead columns is compared with baseline values (unfiltered sample). The percentage of platelets trapped in the filter is calculated, and results are expressed as percentage retention. 3. Platelet aggregation is determined with the use of adenosine diphosphate (ADP) and collagen as aggregating agents. Results are quantified by determining the rate (slope) and the extent of response (%AT). We have determined that ADP-induced aggregation responses differ for men and women 4 ; therefore, it was necessary to provide for this distinction when designating normal ranges on our report form. The lightly shaded area for AT (ADP) indicates that any value greater than 45% is considered normal for female donors; while the heavily shaded area indicates that the normal range for male donors is any value greater than 38%. 4. Platelet factor 3 availability is assessed with a modified method described by Spaet and Cintron. 7 The observable endpoint of this test occurs when fibrin strands begin to form after addition of calcium chloride to a platelet-rich plasma-kaolin mixture. Results are expressed as a function of the speed (recorded in seconds) with which these strands become visible. 5. The bleeding time test is performed with the use

0002-9173/79/0300/0338 $00.65 © American Society of Clinical Pathologists

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Roper, Pamela, and Friereich, Emil J.: The platelet function profile: A new format for recording platelet function tests. Am J Clin Pathol 71: 338-340, 1979. A platelet function profile that provides a concise record of platelet function tests has been developed. This format can be easily modified to meet local requirements or to include hematologic tests unique to each laboratory. (Key words: Platelet function profile; Platelet aggregation; Platelet retention; Platelet count; Platelet factor 3 availability; Bleeding time; Capillary fragility; Platelet volume; Distribution profile.)

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Vol. 71 . No. 3

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from an individual patient, the times at which tests are performed may be indicated by arrows. When sequential studies are not performed, the bottom portion of this form is discarded and the platelet function profile alone remains as a permanent record to be included in the patient's chart. Discussion The platelet function profile is being utilized in our institution to display results from platelet function tests. This form lends itself to concise presentation of data with additional advantages of permitting visualization of temporal fluctuations in results and easy recognition of abnormal values. This type of report form may be adopted for widespread use in laboratories performing tests on patients with hematologic disorders of platelet origin. References 1. Brittin GM, Dew SA, Fewell EK: Automated optical counting of blood platelets. Blood 38:422-430, 1971 2. Kramer J: The determination and evaluation of capillary resistance—a review of methodology. Blood 20:83-93, 1952 3. Mielke CH, Kaneshiro MM, Maher IA, et al: The standardized normal Ivy bleeding time and its prolongation by aspirin. Blood 34:204-215, 1969 4. Roper P, Drewinko B, Hasler D, et al: Effects of time, platelet concentration, and sex on the human platelet aggregation response. Am J Clin Pathol 71:263-268, 1979 5. Roper P, Johnston D, Austin J, et al: Profiles of platelet volume distributions in normal individuals and in patients with acute leukemia. Am J Clin Pathol 68:449-457, 1977 6. Salzman EW: Measurement of platelet adhesiveness: A simple in vitro technique demonstrating an abnormality in von Willibrand's disease. J Lab Clin Med 62:724-735, 1963 7. Spaet T, Clintron J: Studies on platelet factor 3 availability. Br J Haemat 11:269-275, 1965

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of a modified Mielke template,3 which produces a standardized incision 9 mm long by 1 mm deep. Results are recorded as the time (in minutes) from initiation to cessation of bleeding. 6. Platelet volume distribution profiles are obtained with a Coulter Counter Model ZBI attached to a multichannel particle-size discriminator.* This instrument facilitates quantitative measurements of platelets and allows visualization of shifts and temporal fluctuations in subpopulations of platelets with different volumes. Data from this procedure are expressed as the PVD score,5 a single numerical index summarizing the entire range of values obtained for profiles of each individual. This score is used to compare the extent of abnormality of patient profiles with the profile of normal donors. 7. The suction method is used to determine capillary fragility.2 The instrument used in performing this test, the petechiometer,t connects to a suction cup that is placed on the patient's back while suction (negative pressure) is applied for one minute. This procedure is repeated at negative pressures of 5, 10, 15, 20, 25, and 30 mm Hg. Results are expressed as the pressure that induces formation of an abnormal number of petechiae (>10). To display platelet function test results, horizontal lines are drawn on each linear scale at the point that corresponds to the test value obtained. These lines are connected to create a histogram, as shown in the upper portion of Figure 1. The bottom half of the form is a scaled grid that may be used to graph daily platelet counts. When serial studies are conducted on samples

A.J.C.P. • March 1979