Thai King Bhumibol Adulyadej remains in unstable condition at a Bangkok hospital where he is on a ventilator while being treated for liver problems and a blood infection, the royal palace said in a statement Wednesday.
There is growing concern over the health of the 88-year-old king, who has been on the throne since 1946 and is the world's longest-reigning monarch.
Doctors will continue to treat Bhumibol with continuous renal replacement therapy, a common treatment for patients with acute kidney injuries, the palace said.
Earlier Wednesday, members of the royal family including Crown Prince Mahavajiralongkorn paid a visit to the king at Siriraj hospital in Bangkok, local media reported.
The announcement - the third on the king's health in two weeks - has raised anxiety over the royal succession in military-ruled Thailand.
Hundreds of well-wishers flock to the hospital in pink T-shirts signifying good health and yellow T-shirts, the king's colour.
Bhumibol is revered in Thailand, where he is seen as a unifying figure.
Thai stocks plunged since the start of the week, with trading in the red throughout on Wednesday, closing with a 2.5 per cent drop.
Many Thais have gathered at temples to pray for his recovery, while posts with the hashtag #longlivetheking have flooded social media.
Bhumibol spent a majority of the past decade in hospital. His last public appearance was on January 11, when he was seen meeting with hospital staff.