Thrombopoietin measurement in thrombocytosis: dysregulation and lack of feedback inhibition in essential thrombocythaemia.
Essential thrombocythaemia (ET), a myeloproliferative disorder (MPD) manifested by excessive platelet production, lacks a specific diagnostic test to facilitate differentiation from other thrombocytoses. We studied thrombopoietin (TPO) levels in 41 patients with thrombocytosis: 25 ET patients, eight with other MPD, and eight with reactive thrombocytosis. Mean age and platelet counts for these groups were comparable. TPO levels for 96 healthy individuals provided a reference range for normal. The majority of ET patients (19/25 or 76%) had normal TPO levels. No patient with ET had a TPO level below 75 pg/ml, compared with 57% of healthy donors and 8/16 (50%) patients with other thrombocytoses (P<0.05). TPO levels in ET are not appropriately down-regulated, as occurs with cytokines relevant to other MPD. In thrombocytosis, a TPO level <75 pg/ml indicates that ET is unlikely.
Pitcher
L
L
Division of Haematology, Mater Misericordiae Hospitals, South Brisbane, Australia.
Taylor
K
K
Nichol
J
J
Selsi
D
D
Rodwell
R
R
Marty
J
J
Taylor
D
D
Wright
S
S
Moore
D
D
Kelly
C
C
Rentoul
A
A
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010976:Platelet Count; D013920:Thrombocythemia, Essential / Q000097:blood*; D013922:Thrombocytosis / Q000097:blood*; D013926:Thrombopoietin / Q000378:metabolism*
D013926:Thrombopoietin