Platelet kinetics and scintigraphic imaging in thrombocytopenic malaria patients.
Thrombocytopenia is a common occurrence in acute malaria. It is attributed, among other factors, to excessive splenic platelet pooling and a shortened platelet lifespan. The aim of our study was to evaluate the platelet kinetics and sequestration site by isotopic studies in uncomplicated malaria-induced thrombocytopenia. Seven thrombocytopenic malaria patients (74,000+/-36,000 platelets/ micro l) were included in the study. Autologous (111)In-labeled platelet scintigraphy was performed up to 96 hours (h) post injection (p.i.) to evaluate the platelet sequestration site. Late sequestration for the spleen (S) and the liver (L) was analyzed according to the following activity ratios: S (spleen count on the last day of the platelet lifespan / spleen count at 30 min) and L (liver count on the last day of the platelet lifespan / liver count at 30 min). Additionally, platelet survival studies were performed. A normal late sequestration (S: 0.95+/-0.06 and L: 1.04+/-0.08; normal values, S and L: 1+/-0.2.) was observed in all of our patients. The platelet lifespan was reduced (1 to 4 days; normal range, 7-9 days), recovery was normal (mean, 63+/-6%; normal range, 55-75%), and the turnover rate was enhanced (mean, 95,000+/-80,000/ micro l/day; normal value, 35,000+/-4,500/ micro l/ day). According to the results of scintigraphy, the sequestration site by uncomplicated malaria-induced thrombocytopenia appears to be non-splenic and/or hepatic, yet diffuse.
Department of Nuclear Medicine, University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria. georg.karanikas@akh-wien.ac.at
Georgios
G
Karanikas
Konstantin
K
Zedwitz-Liebenstein
Harald
H
Eidherr
Matthias
M
Schuetz
Robert
R
Sauerman
Robert
R
Dudczak
Stefan
S
Winkler
Ingrid
I
Pabinger
Kurt
K
Kletter
D000328:Adult; D000368:Aged; D000818:Animals; D001792:Blood Platelets / Q000737:chemistry* / Q000378:metabolism; D005260:Female; D006801:Humans; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D008288:Malaria / Q000097:blood* / Q000150:complications; D008297:Male; D008875:Middle Aged; D010963:Plasmodium falciparum / Q000378:metabolism; D010966:Plasmodium vivax / Q000378:metabolism; D011877:Radionuclide Imaging / Q000379:methods*; D013154:Spleen / Q000378:metabolism; D013921:Thrombocytopenia / Q000097:blood / Q000209:etiology*; D013997:Time Factors