Nearly one in 10 children in the U.S. are hospitalized for a mental health disorder, according to a new report.

Researchers from the University of California San Francisco (UCSF) Children's Hospital discovered an estimated 4 million children are diagnosed with mental health conditions, yet little is know about which specific disorder are causing adolescents to be hospitalized. 

"Mental health hospitalizations have been increasing in kids, up 24 percent from 2007 to 2010. Mental health is a priority topic for national quality measures, which are intended to help improve care for all kids," Naomi Bardach, lead author of the study said.

Researchers analyzed hospital discharge papers in 2009 from patients aged 3 to 20 years old using two national databases.

More than 40 precent of all pediatric admissions were for depression alone, followed by bipolar disorder and psychosis. Mental health admissions cost $1.33 billion in hospital charges annually.

The report also discovered that children at general hospitals were admitted for mental illness three times more frequently than at exclusively children's hospitals, leading to the possibly that general hospitals have greater capacity to deliver inpatient psychiatric care. 

"These costly hospitalizations are a heavy burden for families and patients," Bardach said. "We need to define what the optimal care is for children with these conditions so that hospitals can consistently deliver the best care for every child, every time."