Lead author Dr. Cheryl Tran of the University of Michigan in Ann Arbor and colleagues used data on discharge records from the Healthcare Cost and Utilization Project Kids' Inpatient Database, from 1997, 2000, 2003 and 2006.
Tran and colleagues hypothesize the increasing hospitalizations may be due in part to the rise in childhood obesity.
Overall, the most common diagnoses for hospitalized children were pneumonia, acute appendicitis and asthma -- but convulsive disorder, headache, obesity and systemic lupus erythematosus were the most common secondary diagnoses when hypertension was the primary diagnosis, the study found.
When high blood pressure was part of a diagnosis, the most common primary diagnoses were lupus, complications of kidney transplant, pneumonia and acute proliferative glomerulonephritis, a condition in the kidney that causes inflammation that can result in hypertension.
"A child with high blood pressure is at increased risk for having high blood pressure in adulthood and the heart and stroke risks that come with that diagnosis," Tran said in a statement.
Hypertension is present in 1 percent to 3 percent of children in the United States, but hospital care for hypertensive children reached an estimated $3.1 billion in 2006, the study said.
The findings were published in the journal Hypertension.