Immunological and functional protein S, protein C and antithrombin III
levels and anticoagulant responses to activated protein C were measur
ed in 24 patients with stroke in childhood. No hereditary deficiencies
were found. The protein S levels in healthy controls of younger age d
id not differ from the adult levels. For optimal screening of protein
S deficiency, measurements using functional as well as immunological a
ssays are recommended. Appropriate criteria for the diagnosis of the d
eficiencies must be carefully applied if unnecessary anxiety and inapp
ropriate treatment of children are to be avoided.