Veteran actor Dilip Kumar was admitted to Lilavati Hospital in Bandra on Wednesday.
Doctors said the actor was not passing urine, which became a cause for concern.
Several tests were carried out, but the medical team is yet to decide whether he would require dialysis.
The 94-year-old has made several visits to the hospital in the last few years.
A doctor said the actor’s condition is ‘not stable’. He is in the intensive care unit and is being monitored closely.