Reticulated platelets (RP) are the youngest platelets in the circulati
on and can be measured by analysing the RNA content of platelets from
whole blood or platelet-rich plasma by flow cytometry. Increased RP ar
e indicative of increased production of platelets. Despite the current
lack of standardization for the measurement of RP, it is useful in th
e assessment of patients with ITP by aiding the distinction of these p
atients from those with decreased platelet production. RP counts also
have a role in the assessment of the complicated patient with multiple
possible aetiologies for thrombocytopenia. Measurement of the RP coun
t may hold predictive value for marrow recovery following myelosuppres
sive or myeloablative chemotherapy, and may play a role in monitoring
the administration of the various thrombopoietins currently under clin
ical trial.