Is there any indication for hydroxyurea in patients with sickle cell trait?  

No. Of course, be sure it is the correct diagnosis and not HgA + HgS (beta+) which, as you know, shows HgA and HgS on electrophoresis and can/will be called trait if not looked at by someone experienced to note if A> S or if S > A. If MCV is low. If HgA2 is up. HgF up etc... If indirect Bili/...

There is no indication for hydroxyurea. Individuals with sickle cell trait are not expected to sickle (no HbS polymerization) at sea level and low altitudes. Sickling complications may occur at high altitudes and in other extreme circumstances associated with exceptionally strenuous exertion, severe...