Increased basophils (> 0.1 x 10^9/l) seen in:
- viral infections
- ulcerative colitis
- systemic mastocytosis
- myeloproliferative disorders:
- chronic myeloid leukaemia
- polycythaemia rubra vera
Basophilia does not characteristically occur in secondary polycythaemia.
Note that excessive basophilia in chronic myeloid leukaemia may indicate the transformation into an accelerated or 'blastic' phase.