indium-oxine and Purpura--Thrombocytopenic

The kinetics of 111In-oxine-labeled platelets was studied in 37 patients with idiopathic thrombocytopenic purpura and in 12 control subjects using gamma-chamber. A comparison was made of the parameters of the kinetics, survival and sequestration type of platelets, as well as their recovery and exchange. In less severe processes the splenic type, while in more severe disease--the hepatic type of sequestration prevailed.

Topics: Adolescent; Adult; Aged; Blood Coagulation; Blood Platelets; Child; Female; Humans; Indium Radioisotopes; Kinetics; Male; Middle Aged; Organometallic Compounds; Oxyquinoline; Purpura, Thrombocytopenic; Radionuclide Imaging

The kinetics of autologous 111In-labelled platelets were studied in 26 patients with ITP. The platelet mean life time (MLT) was considerably shortened, the platelet in vivo recovery slightly lowered and the platelet turnover normal. Comparative studies of the kinetics of simultaneously injected 111In- and 51Cr-labelled platelets in 10 patients showed the MLT and turnover of 51Cr-platelets to be shorter and higher, respectively, than those of 111In-platelets, suggesting that 51Cr-labelling in ITP may underestimate platelet MLT and overestimate platelet turnover. Our results confirm that accelerated platelet destruction is an important pathogenetic factor in ITP, and that the platelet concentration may be influenced by increased splenic platelet pooling and by inability of the bone marrow to respond adequately to the low platelet count. Our scintigraphic studies showed that the spleen played an important role for platelet destruction in most patients, with the liver contributing in some patients.

Topics: Adolescent; Adult; Aged; Blood Platelets; Bone Marrow; Cell Survival; Child; Female; Humans; Hydroxyquinolines; Indium; Infant; Kinetics; Liver; Male; Middle Aged; Organometallic Compounds; Oxyquinoline; Platelet Count; Purpura, Thrombocytopenic; Radioisotopes; Radionuclide Imaging; Spleen

The kinetics of platelets labelled with 111In have been studied in a series of 175 subjects including 18 normal volunteers, and 12 patients with idiopathic thrombocytopenic purpura (ITP), but excluding patients in whom there was scintigraphic evidence of intravascular platelet consumption. From analysis of the kinetics, the following parameters were calculated: splenic blood flow (SBF), intrasplenic platelet transit time (t-), splenic platelet pool capacity (expressed as a percentage of the total circulating platelet population), the fraction of the dose of labelled platelets ultimately destroyed in the spleen and the mean platelet life span (MPLS). SBF increased with increasing spleen size up to values of 25% total blood volume (TBV) per min. Some patients with immune complex related diseases were identified with elevated SBF (up to 24% TBV min-1) but without significant splenomegaly. Patients with cardiac decompensation had reduced SBF relative to spleen size. t- showed no relationship with spleen size. It tended to fall in patients who had high SBF relative to spleen size and to rise in those with low SBF relative to spleen size; i.e. it was inversely related to splenic perfusion (flow per unit tissue volume). The splenic platelet pool capacity is dependent on platelet input (SBF) and splenic platelet clearance (reciprocal of t-), and showed a close relationship with spleen size. When all subjects except those with ITP were considered, splenic platelet destruction showed a good correlation (r = 0.70, n = 42, P less than 0.001) with the splenic platelet pooling capacity. The ratio of the fraction of platelets destroyed in the spleen to the fraction pooling there, the D/P ratio, was approximately unity and did not appear to vary with MPLS, spleen size or the patient's condition, except in ITP where it varied between about 0.5 and 2. This variation in ITP was thought to be the result of an immune mediated re-direction of reticulo-endothelial platelet destruction. It is suggested that the D/P ratio, rather than the absolute quantity of 111In labelled platelets destroyed in the spleen, may be a more useful predictor of response to splenectomy since it takes into account the observed, appropriate, tendency for the spleen to destroy platelets in proportion to its platelet pooling capacity.

Topics: Blood Flow Velocity; Blood Platelets; Cell Survival; Humans; Indium; Organometallic Compounds; Oxyquinoline; Pentanones; Purpura, Thrombocytopenic; Radioisotopes; Spleen; Time Factors