RESUMEN

Platelet aggregation was undertaken in platelet rich plasma in 34 heat-stroke patients during the Muslim pilgrimage (Haj) to Makkah; 18 were males and 16 were females; their ages ranged from 36 to 80 years (mean SD = 58 10). Platelet aggregability, on arrival at the Heatstroke Centres, was markedly inhibited in response to adrenaline, collagen, arachidonic acid and ristocetin but not to ADP. Responses to decreasing ADP doses (20.0, 2.0, 1.0 and 0.5 micromol/l) showed hyperaggregability in 12 patients, inhibited responses in 16 and normal responses in 6 patients. Aggregation responses were not significantly different when comparing patients with bleeding manifestations ( n = 10), with those without bleeding ( n = 24). Haemostatic parameters including plasma fibrinogen, ATIII and platelet count, were markedly reduced in the two patient groups who showed hyperaggrebable and depressed aggregation responses, but not in those with normal responses. These results lead us to conclude that: (1) platelet activation is a frequent feature of heatstroke; (2) in heatstroke altered aggregation responses, whether hyperaggregable or depressed, occur simultaneously with a consumption coagulopathy.

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This study describes two siblings (a boy and a girl) affected with congenital dyserythropoietic anaemia type I. It is the seventh familial occurrence reported. The girl presented in the neonatal period with anaemia, jaundice and hepatosplenomegaly and required 4 blood transfusions in the first 7 months of life, while her brother was discovered to be anaemic and jaundiced only at the age of 2 years and did not receive any blood transfusion.

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Haemostatic measurements were undertaken in 132 patients diagnosed with heat stroke during the pilgrimage to Makkah, in two successive summers of 1989-90. The control group comprised 49 patients, all pilgrims, with a wide range of clinical conditions, but without hyperpyrexia or deranged haemostasis. Heat stroke patients showed (i) significant prolongation of the prothrombin (PT), activated partial thromboplastin (aPTT) and thrombin times (TT) but normal reptilase time (RT); (ii) significant reduction in plasma levels of antithrombin III (AT-III), factor V, proteins C and S, plasminogen activator inhibitor (PAI) and platelet count; (iii) increase in plasma factor VIII, tissue plasminogen activator (t-PA) and serum FDP; (iv) no significant changes in plasma fibrinogen, plasminogen, alpha 2-antiplasmin and factors VII and X. Heat stroke patients were then grouped into those with and those without bleeding symptoms. Bleeders showed greater prolongation of the PT, aPTT and TT and significant reductions in fibrinogen, AT-III, factors V, VIII and X, plasminogen, alpha 2-antiplasmin and platelet count. Logistic regression and discriminant analysis showed that AT-III was the parameter associated most with heat stroke and reliable enough to predict its occurrence, whether or not bleeding occurred. The results indicate that activation of the haemostatic mechanism, consumptive in nature, regularly accompanies heat stroke and highlights the physiological role of AT-III in checking this activation process.

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Six hundred sixty-three children aged 1 to 16 years with thrombocytosis (defined as a platelet count of more than 500 x 10(9)/L) seen in a university hospital over a 1-year period were studied prospectively for etiology. The causes of thrombocytosis were infection (30.6%), hemolytic anemia (19.3%), tissue damage (15.2%), rebound thrombocytosis (14.8%), chronic inflammation (4.1%), renal disorders (4.1%), and malignancy (2%). Thrombocytosis associated with multiple, simultaneous causative factors was seen in 3.3% of cases. Among all patients with infections, osteomyelitis and septic arthritis were associated with higher platelet counts than other infections (P < .0001). Thrombocytosis secondary to infections was significantly more common in children under 5 years of age, whereas chronic inflammation, malignancy, and renal disorders were more common causes of thrombocytosis in children over 5 years of age. Thrombocytosis of 1 million or more platelets was seen in 13 (2%) children. No thrombocytosis-related complications were seen in any children, and none required any specific treatment. Thrombocytosis is a frequent finding in children. It is due to a variety of etiologic factors and is of little clinical discriminatory value. It is often due to an acute-phase phenomenon in response to infection, tissue damage, blood loss, or anemia, and is rarely due to malignancy.

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An infant with severe combined immunodeficiency is described in whom a refractory anemia and thrombocytopenia developed after the age of 6 months, associated with poor growth and frequent episodes of upper respiratory tract infections and diarrhea. He required frequent blood and platelet transfusions. Bone marrow biopsy provided evidence that the anemia and thrombocytopenia were the results of myelofibrosis which was secondary to vitamin D deficiency. Therapy with 1,25-dihydroxycholecalciferol resulted in resolution of the hematologic and skeletal abnormalities, but he remained susceptible to recurrent serious infections and died at the age of 13 months.

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Over a five-year period extending from January 1986 to December 1990, seven cases of pernicious anemia in Saudi patients were diagnosed at King Khalid University Hospital in Riyadh. There were five males and two females. The age range was 45 to 73 with a mean age of 61 years. The presenting symptoms, laboratory features and the disease pattern were similar to those described in northern European patients with the possible exception of male predominance in our patients. One patient demonstrated an interesting phenomenon of masking the macrocytosis of pernicious anemia by concurrent beta thalassemia minor. No association with any other autoimmune diseases was detected in any of our patients.

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A total of 777 patients with thrombocytosis, defined as a platelet count of greater than 500 x 10(9)l-1, seen in a University hospital over a 1-year period, were studied prospectively for aetiology. The most frequent causes of thrombocytosis were infection (21.9%), rebound thrombocytosis (19.4%), tissue damage (17.9%), chronic inflammatory disorders (13.1%) and malignancy (5.9%). Thrombocytosis associated with multiple causative factors, occurring simultaneously, was seen in 6.1% of cases. Thrombocytosis of greater than or equal to 1 million x 10(9)l-1 was found most frequently in patients with multiple aetiological factors occurring at the same time, in myeloproliferative disorders, or in postsplenectomy patients.

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We report a case of Wolman's disease that is apparently the first to be reported in a Jordanian infant. The clue to diagnosis was the radiological evidence of bilateral adrenal calcifications and foam cells in bone marrow. The disease was confirmed by skin fibroblast culture which showed decreased 'acid esterase' activity.

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Sera obtained during the Hajj seasons of 1985, 1986, 1987 and 1988 from 125 heat stroke patients were collected and subjected to chemical analysis which included determination of glucose, lactate, cholesterol, and triglycerides, as well as assay of T3, T4, TSH and cortisol. Hyperglycaemia and lactic acidaemia were found to be the most frequent metabolic abnormalities. The changes in cholesterol did not exhibit a specific pattern. Triglycerides were significantly elevated in only 6% of patients. Cortisol levels were very significantly elevated in precooled patients. Although the mean T3 levels remained within the normal range, the mean concentration on admission was significantly higher than the post-cooling mean. TSH and T4 levels did not show significant changes.

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The trigger of the coagulopathy that complicates heat stroke is obscure, but direct platelet activation by heat is a possibility we set out to study. Platelet rich plasma (PRP), prepared from blood donors, was incubated at increasing temperatures (38-45 degrees C) and then platelet aggregation was undertaken in response to decreasing low doses of ADP (less than 2.0 mumol/l). Hyperaggregability was manifested when the incubation temperature reached 43 degrees C and was maximum at 44 degrees C before complete inhibition of responses at 45 degrees C. The platelet hyperactivity induced by heating at 44 degrees C persisted after reincubating PRP samples at 37 degrees C. These platelet responses could not be triggered in PRP samples prepared from subjects after the overnight ingestion of aspirin or after the addition of aspirin to PRP before starting the heating procedure. However, aspirin was less effective when added to PRP after the appearance of the heat-induced hyperaggregability. In conclusion, these results indicate that platelets can be activated directly by heat. This mechanism which may be operational in heat stroke, is unaffected by cooling (body cooling being basic in the management of heat stroke) but can be prevented by the early administration of aspirin.

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