White, 58, is undergoing dialysis treatment to stabilize his condition, Island Def Jam Music Group said in a statement Friday.
The singer's family refused to comment on whether he is hospitalized or undergoing treatment at his Los Angeles home.
White is known for such romantic songs as "Can't Get Enough of Your Love, Babe" and "You're the First, the Last, My Everything."
He had been working on a new studio album, said Sheila Richman, spokeswoman for Island Def Jam.
White was hospitalized in August 1999 for a blood pressure problem, which forced him to cancel several live performances with the group Earth, Wind & Fire.
Despite reaching his peak of popularity in the 1970s, White won his first two Grammys in 2000 for best male and traditional R&B vocal performance for "Staying Power."
He also has made appearances on the TV shows "Ally McBeal" and "The Simpsons."