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Clinical Research BRITISH -MEDICAL JOURNAL VOLUME 285 7 AUGUST 1982 397 Br Med J (Clin Res Ed): first published as 10.1136/bmj.285.6339.397 on 7 August 1982. Downloaded from CLINICAL RESEARCH Prediction of haemorrhagic diathesis in thrombocytopenia by mean platelet volume A ELDOR, M AVITZOUR, R OR, R HANNA, S PENCHAS Abstract Introduction The Coulter counter, model S Plus, provides a platelet Severe thrombocytopenia is usually associated with the develop- count and a mean platelet volume in all routine specimens ment of haemorrhagic diathesis, though not all patients with ofblood for cell count. The value of mean platelet volume severe thrombocytopenia develop a bleeding tendency.1 2 Platelet in the prediction of the haemostatic potential ofthrombo- number alone may therefore be an insufficient predictor of cytopenic patients was investigated in 175 patients with bleeding tendency in a particular patient. Several investigators haematological disorders who underwent 1473 blood have suggested that platelet size also affects the haemostatic counts over five months. Eighty-four haemorrhagic potential of some patients because the function of platelets episodes were detected, most in thrombocytopenic depends on their size under normal conditions and, particularly, patients. The mean platelet volume of patients with in thrombocytopenic states.' 15 Using in-vitro adhesion and haemorrhagic tendency was significantly lower (5-52 ± SD aggregation studies3-9 and in-vivo tests and observations such 017 fl) than that of patients without these tendencies as bleeding time and bleeding episodes in patients'0-12 it was http://www.bmj.com/ (7-87 ± SD 1-75 fl) (p <0 001). In cases of severe thrombo- evident that large platelets were haemostatically more active than cytopenia (<20x 109/l platelets) haemorrhagic episodes small platelets and functioned more efficiently in the prevention were frequent; however, the frequency of bleeding was of haemorrhagic tendency.' 12 It has been suggested that platelet considerably lower in cases in which the mean platelet size as well as number must be considered when predicting volume was higher than a suggested cut-off point of haemostatic potential in thrombocytopenic states.2 6-4 fl. Discriminant analysis selected mean platelet Until recently, platelet sizing was an elaborate and tedious volume as more important than platelet count for procedure performed in only a few laboratories equipped with prediction of haemorrhagic state in severe thrombo- special expensive instruments. The introduction of the Coulter on 2 October 2021 by guest. Protected copyright. cytopenia. counter, model S Plus, has made it possible to determine In view of the useful discrimination that mean platelet platelet size from any routine specimen of blood for cell count.'3 volume provides between thrombocytopenic patients Platelet size as measured by this Coulter counter is expressed as who bleed and those who do not bleed, it may serve as a the mean platelet volume. We examined the mean platelet guide to predict the danger of haemorrhage and the need volume of all patients treated by the department of haematology for prophylactic platelet transfusion. from January to May 1981. We examined the association between the number and the size of the platelets with the appearance of a haemorrhagic diathesis. Patients taking anticoagulants or anti- aggregating agents and those with abnormal results of coagulation tests or congenital haemorrhagic disorders were excluded from this study. The results indicated that the platelet size, expressed Department of Haematology, Hadassah University Hospital, as mean platelet volume, is a valuable variable for the prediction Jerusalem, Israel 91120 of haemorrhagic diathesis in thrombocytopenic patients. A ELDOR, MD, senior lecturer R OR, MD, house officer R HANNA, medical laboratory technician Department of Social Medicine, Hebrew University-Hadassah Materials and methods School of Public Health and Community Medicine, Jerusalem, All patients under the care of the department of haematology either Israel 91120 in the day care unit or as inpatients were considered for the study. M AVITZOUR, BSC, statistician senior lecturer in medicine Blood samples-Samples were obtained daily from these patients and S PENCHAS, MD, MSC, were collected into dipotassium EDTA in a concentration of 1 mg/ml. 398 BRITISH MEDICAL JOURNAL VOLUME 285 7 AUGUST 1982 All samples were processed in the Coulter counter model S Plus TABLE II-Mean platelet volume and platelet count in different patient groups. Br Med J (Clin Res Ed): first published as 10.1136/bmj.285.6339.397 on 7 August 1982. Downloaded from within one hour of venesection. The patients were checked daily for Results are means±SD signs of haemorrhagic diathesis: those patients exhibiting any positive signs of bleeding underwent routine coagulation studies, which Mean platelet Mean platelet No of No of included determination of partial thromboplastin time, prothrombin Group count x 109/l volume fl patients tests time, thrombin time,14 and fibrinogen degradation products (Thrombo- 1 12 4±6 5* 6-6±1-83t 31 152 2 52-2±43-5 7-9±2-4 60 362 Wellcotest, Wellcome Research Laboratories, Beckenham, England). 3 235 2 ±180 3 7 8 ±5-5 141 836 Patients with congenital haemorrhagic disorders or found to have 4 622-1 ±196-5 8 06±4 2 22 114 abnormalities in these coagulation tests were excluded from the study. 5 255-3 ±76-7 8-48±1 0 200 200 Patients treated with or anticoagulant drugs anti-aggregating agents *Results adjusted to cluster sampling. were also excluded. A total of 175 patients (98 male, 77 female; age tDifference between group 1 and each of the other groups was significant (p < 0-001) range 8-93 years) were included. Patients receiving platelet trans- by Student's t test. fusions were excluded from the study for 14 days- after the last transfusion. Only one blood sample was taken during any episode of bleeding and only one examination of blood allowed for each patient daily (usually in the morning). Punch cards were prepared for each examination; they included the results of the various haematological 20 solIo o 00 o 000 o 0000 00 tests printed by the Coulter counter as well as the identifying number, 1 00000000 00 175 0 00 0 00 sex, and age of the patient, a code for the diagnosis of his disease, and * ol 00 0 0 000 00 0 a code for the existence and type of haemorrhage-purpura, ecchy- 0o0 15 * _ I0 oocoo mosis, and so on. Blood counts were also performed on normal subjects @0. 0 000 0 0 00 0 0 _125 * *0 -Io 00 0o0 0 and served as references. ema 0 00 0 0 0 Quality control for the Coulter counter, model S Plus, was estab- 10 . 0-0 -"*sm so 0 -o0 lished to the instructions of the manufacturer. A 0 daily according daily *o " *0 lb 7.5 *00 @5 0 calibration was performed using the 4C Plus normal haematology , 0000 00 reference control Electronics Northwell @00 0@0 (Coulter Ltd, Drive, England). a- The results for white blood red blood and * 0 0 0 cells, cells, haemoglobin, 25 *0 With hoemorrhoge * mean corpuscular volume were comparable to the results obtained Without hoemorrhoge 0 from the Coulter counter model S, while platelet counts correlated 0 well with phase microscopy counts. 4 5 6 7 8 9 10 11 12 Statistical analysis of the data-Punched cards were processed in a Mean platelet volume (fl) Cyber Control Data Co (USA) computer, model 172, and analysed in 179. The Statistical Mean platelet volume in patients with severe thrombocytopenia: a Cyber computer, model Package for Social association with platelet number and with haemorrhagic diathesis Sciences, version No 8, was used for analysis of the data.15 The (Scattergram constructed by the Cyber computer). following statistical tests were used: Student's t test, discriminant analysis, and sensitivity and specificity indices.'6 The data was referred to as cluster sampling. Each patient represents a cluster of cell counts. Intraclass correlations, in each subgroup of platelet numbers considerably lower than that of the other groups, and the difference were used to compute variances for cluster sampling.'7 The t tests was statistically significant (p < 0-001). The figure shows the associa- were computed using those variances. Discriminant analysis was tion between mean platelet volume and platelet time among severely performed only on those patients with severe thrombocytopenia, in thrombocytopenic patients (group 1). which intraclass correlations for both mean platelet volume and platelet Bleeding episodes-Eighty-four bleeding episodes were observed in number were low (0 18 and-0 19, respectively), hence we analysed our 28 patients. Most haemorrhages were associated with severe thrombo- sample as a simple random sample. cytopenia (group 1) since no other abnormalities were detected by the screening coagulation tests. One patient in group 3 had two haemor- rhagic episodes that could not be attributed to any other coagulation abnormality. The most frequent types of bleeding were purpura (45%) Results and mucosal haemorrhages (33%), which occurred mainly in the http://www.bmj.com/ Table I gives the list of different diseases diagnosed in the 175 mouth. Other types of haemorrhage included: ecchymosis (11%), patients who completed the study, the number of cases in each vaginal bleeding (4%), haematuria (2%), epistaxis (4%), and wound and the number cell counts A of 1473 bleeding (1%). No severe haemorrhages were observed in these category, of performed. total because received immediate cell counts were performed, ranging from one to 66 tests per patient. patients they platelet transfusions. The results of the cell counts were classified according to platelet To further evaluate whether platelet size plays a part in the patho- number: those with less than 20 x 109/l platelets were classified as genesis of haemorrhagic diathesis, the results of the blood tests in each showing severe thrombocytopenia (group 1), those with 20-100 x 109/1 group were divided into two subgroups: those of patients with and platelets as showing moderate thrombocytopenia (group 2), those with those of patients without haemorrhagic diathesis (table III).
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