The three times MotoGP world champion, who is joining compatriot and reigning champion Marc Marquez at the factory Honda team next year, then went to Buriram hospital for a further scan.
Lorenzo arrived in Thailand nursing a foot injury from the previous Aragon Grand prix in Spain, where he was flipped off his bike at the start.
Friday's turn three accident also threw Lorenzo into the air, the Spaniard landing heavily while his bike was wrecked. He was carried away on a stretcher.
Italian team mate Andrea Dovizioso was fastest in the session.
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Lorenzo is fourth in the MotoGP standings, 116 points behind Marquez with five races remaining.
(Reporting by Alan Baldwin in London, editing by Ken Ferris)
