The spleen acts as a major site of clearance of antibody-coated platel
ets from circulation in immune thrombocytopenia (ITP). Splenectomy car
ries a high cure rate. The biological effect of a single therapeutic d
ose of ultrasound directed transthoracically to the spleen at 1 MHz an
d 1 W/cm(2) with a mean treatment time of 5 min as generated by Sonopu
ls 463 (Enraf Nonius) was studied in 30 children with ITP (20 chronic,
10 acute) aged 8-14 years (median 10) and 10 control children. The ch
ronic ITP cases had platelet counts (PC) of 20-50 x 10(9)/l (mean 36 x
10(9)/l), showed peak responses at 4 h after exposure 5-18 x 10(9)/l
(mean 10 x 10(9)/l) in 70% of cases, while the remaining 6 patients sh
owed either no change in PC (n = 3) or a decline in PC (n = 3) 5-7 x 1
0(9)/l. Children with acute ITP had pretreatment PC of 30-50 x 10(9)/l
(mean 40 x 10(9)/l). All had increments of PC after ultrasonic exposu
re (10-30 x 10(9)/l; mean 18 x 10(9)/l) peaking at 4 h. Six patients w
ith acute ITP maintained the rise in PC while in an other 4, PC return
ed to baseline in 24 h. The control group showed no change in PC. This
therapy was well tolerated and was not associated with significant ch
ange in serum lactate dehydrogenase (LDH) levels except in 2 cases wit
h chronic ITP, in whom the LDH levels doubled. All above results were
reproduced when therapy was repeated 2 weeks later. In conclusion, thi
s therapy would seem to be safe and well tolerated at such a dose. The
effectiveness, rapidity and low cost of this therapy compared with co
nventional approaches may suggest its use as an alternative therapy in
ITP.