King Harald of Norway has been hospitalized for treatment related to hemolytic anemia, a blood disorder, according to the royal palace.

The 89-year-old monarch was admitted to the National Hospital after treatment with cortisone caused fluid to accumulate in his body.

Harald has been on sick leave for two weeks, with his son, Crown Prince Haakon, serving as regent during his absence.

The king has experienced several health problems in recent years, including hospitalizations for an infection and heart issues that led to him receiving a permanent pacemaker, the AP has reported.

Harald has served as Norway’s king since 1991.