Nationals optioned RHP Nathan Karns to Double-A Harrisburg.
Nationals prospect right-hander Nathan Karns (leg) has been cleared to throw a bullpen session.
Nathan Karns will undergo an X-ray and an MRI on his right leg.
Nationals manager Davey Johnson said Friday that prospect right-hander Nathan Karns is dealing with a right leg issue.
Nationals purchased the contract of RHP Nathan Karns from High-A Potomac.