Hellickson (shoulder) announced his retirement from professional baseball Friday, Tommy Birch of The Des Moines Register reports.

Hellickson suffered a shoulder setback and is unlikely to pitch this season, Craig Mish of FNTSY Sports Radio reports.

Hellickson (shoulder) was activated off the 60-day injured list Sunday.

Hellickson (shoulder) tossed two scoreless innings Wednesday in a rehab appearance for the Nationals' rookie-level Gulf Coast League affiliate. He gave up a base hit and struck out two in the 12-pitch outing.