FRIDAY, June 20 (HealthDay News) -- A drug that has shown some effectiveness in treating sickle cell anemia is not being used often enough by doctors who are uncertain about its proper use and possible long-term effects, according to a new report.

Researchers at Johns Hopkins University say their extensive review of studies on hydroxyurea clearly shows its helps people with sickle cell anemia, an inherited disorder that affects mostly people of African and Hispanic heritage. Their report, published in the June 17 Annals of Internal Medicine, concluded that hydroxyurea is a viable treatment option for now, but more quality research is needed.

About 70,000 people in the United States have sickle cell anemia, in which sickle-shaped blood cells periodically clump inside blood vessels, blocking circulation. This results in severe anemia, an increased risk of infections or strokes, and extreme episodes of pain that last for days.

The U.S. Department of Health and Human Services asked Johns Hopkins researchers to examine all previously published studies on hydroxyurea in an effort to increase awareness about the drug's potential.

"We know that many people with sickle cell disease aren't being offered this drug, which is the only one we have to treat this disease," Dr. Sophie Lanzkron, director of the Sickle Cell Center for Adults at Johns Hopkins, said in a prepared statement.

The team analyzed 246 quality articles on the drug and concluded it clearly works. The data suggests that once patients started taking hydroxyurea:

• Their episodes of painful sickle cell "crises" fell by 68 percent to 84 percent.
• Their hospital admissions declined by 18 percent to 32 percent.
• Their levels of fetal hemoglobin, a blood component that appears to eases sickle cell symptoms, increased by 4 percent to 20 percent.

The review also found hydroxyurea impairs sperm development in mice and may do the same in humans. The team, though, could not conclusively back theories that hydroxyurea increased or decreased the risk of leukemia or other tumors, leg ulcers and pregnancy complications from its review.

"It's clear from our literature review that hydroxyurea works, but we need to do much more work to understand how it works and the best ways to use it," Lanzkron says.

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