The British singer was forced to bow out of the band's promotional commitments this week (begs15Apr13) to undergo an operation in Los Angeles on Thursday, the day of his 20th birthday, to repair a haemorrhaging nodule on his vocal cords.
Sykes used his Twitter.com page to keep fans updated on his progress as he prepared to check into hospital, revealing he was "nervous" and struggling to sleep on Wednesday (17Apr13) as he had "so much on my mind".
He returned to the social networking site on Thursday after emerging from the operating room, and reached out to his devotees to express his appreciation for their kind words and birthday messages.
He tweeted, "Out of surgery... what a way to spend my birthday! Not gonna lie, I have been completely overwhelmed by all of the love, support and birthday wishes from you guys. You are all amazing!!"
Justin Bieber's manager Scooter Braun, who also represents the boyband, added, "Happy to hear @NathanTheWanted is out of surgery and getting rest. HappyBrithdayNath (sic)."
The singer's bandmates will continue to fulfill their work commitments without Sykes as he recovers from the operation.