Abstract
Laboratory methods used for the diagnostics of thrombocytopenias are reviewed. Differential diagnosis is usually carried out between immune and hypoproductive forms of thrombocytopenia. Immune thrombocytopenias are caused by appearance in blood of antiplatelet abtibodies and accelerated destruction of platelets sensibilized by those antibodies, and hypoproductive thrombocytopenias - by impaired platelet production in the bone marrow. Main directions of the laboratory diagnostics of thrombocytopenias - analysis of auto- and alloautoantibodies and evaluation of platelet production and turnover in the blood stream. The following methods are used for the investigation of antiplatelet antibodies: 1) measurement of platelet associated immunoglobulins; 2) determination of circulating antibodies reacting with platelets; 3) determination of antibodies using antigen specific methods - by their reactivity with isolated platelet antigens (glycoproteins). Efficacy of platelet production could be assessed by measuring in blood the amount of "young" (reticulated) platelets. One more method for the evaluation of platelet production as well as the rate of platelet turnover - measurement of plasma soluble glycocalicin, glycoprotein Ib fragment shed from the surface of platelets upon their destruction in spleen and liver. In patients with immune thrombocytopenia autoantibodies are evaluated in all cases, the percentage of reticulated platelets is significantly increased and the amount of plasma glycocalicin is within the normal range or increased. In patients with hypoproductive thrombocytopenia autoantibodies are not detected or detected at low level, the percentage of reticulated platelets is within the normal range or slightly increased and the amount of plasma glycocalicin is lowered. Diagnostics of hapten forms of immune thromocytopenias (heparin-induced thrombocytopenia and others) and of alloimmune thrombocytopenias (neonatal alloimmune thrombocytopenia in particular) are considered in the separate sections of this review.
Highlights
Laboratory methods used for the diagnostics of thrombocytopenias are reviewed
Immune thrombocytopenias are caused by appearance in blood of antiplatelet abtibodies and accelerated destruction of platelets sensibilized by those antibodies, and hypoproductive thrombocytopenias – by impaired platelet production in the bone marrow
The following methods are used for the investigation of antiplatelet antibodies: 1) measurement of platelet associated immunoglobulins; 2) determination of circulating antibodies reacting with platelets; 3) determination of antibodies using antigen specific methods – by their reactivity with isolated platelet antigens
Summary
Сведения об авторах: Хаспекова Светлана Георгиевна – к.б.н., с.н.с. Васильев Сергей Александрович – д.м.н., проф., врач-гематолог. При гипопродуктивных тромбоцитопениях количество ретикулярных тромбоцитов снижено (угнетение продукции), но их процентное содержание в популяции не изменено или даже несколько повышено – в первую очередь из-за резкого снижения общего количества тромбоцитов. В связи с этим при ИТП процентное содержание ретикулярных тромбоцитов в популяции (на фоне снижения общего количества тромбоцитов) резко повышено, как по сравнению с нормой, так и с гипопродуктивной тромбоцитопенией [9, 10]. Количество гликокалицина в плазме при гипопродуктивных тромбоцитопениях снижено вследствие уменьшения количества появляющихся в крови и соответственно разрушаемых тромбоцитов, т.е. Что при тромбоцитопениях иммунного генеза основной причиной снижения числа тромбоцитов является их ускоренное разрушение, у части больных может регистрироваться и некоторое угнетение тромбоцитопоэза (обычно при хроническом течении заболевания), которое предположительно обусловлено действием аутоантител на мегакариоциты костного мозга [4,5,6].
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