A normal platelet count is considered to be in the range of 150,000–450,000 per microlitre (μl) of blood for most healthy individuals. Hence one may be considered thrombocytopenic below that range, although the threshold for a diagnosis of<unk>  is not tied to any specific number. The incidence of<unk>  is estimated at 50–100 new cases per million per year, with children accounting for half of that number. At least 70 percent of childhood cases will end up in remission within six months, even without treatment. Moreover, a third of the remaining chronic cases will usually remit during follow-up observation, and another third will end up with only mild thrombocytopenia (defined as a platelet count above 50,000). A number of<unk>  related genes and polymorphisms have been identified as influencing predisposition to<unk> , with FCGR3a-V158 allele and KIRDS2/DL2 increasing susceptibility and KIR2DS5 shown to be protective.<unk>  is usually chronic in adults and the probability of durable remission is 20–40 percent. The male to female ratio in the adult group varies from 1:1.2 to 1.7 in most age ranges (childhood cases are roughly equal for both sexes) and the median age of adults at the diagnosis is 56–60. The ratio between male and female adult cases tends to widen with age. In the United States, the adult chronic population is thought to be approximately 60,000—with women outnumbering men approximately 2 to 1, which has resulted in<unk>  being designated an orphan disease. The mortality rate due to chronic<unk>  varies but tends to be higher relative to the general population for any age range. In a study conducted in Great Britain, it was noted that<unk>  causes an approximately 60 percent higher rate of mortality compared to sex- and age-matched subjects without<unk> . This increased risk of death with<unk>  is largely concentrated in the middle-aged and elderly. Ninety-six percent of reported<unk> -related deaths were individuals 45 years or older. No significant difference was noted in the rate of survival between males and females.
Immune thrombocytopenic purpura
Drug-induced thrombocytopenic purpura
Thrombotic thrombocytopenic purpura
Heparin-induced thrombocytopenia
Gray platelet syndrome
Quebec platelet disorder
Sticky platelet syndrome
Pseudo gray platelet syndrome