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Health

Altitude, Asthma, Heat Can Lead To Sickling

Reporting
Dr. Maria Simbra

PITTSBURGH (KDKA) ―

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Steelers safety Ryan Clark almost died two years ago when he played in the mile-high city of Denver.

He ran into trouble because of sickle cell trait. But he's the exception rather than the rule.

"Having sickle cell trait does not preclude you from playing sports at any level," says Dr. Lakshmanan Krishnamurti, a hematologist at Children's Hospital Pittsburgh.

Even so, there have been isolated reports since the 1950's of problems among fighter pilots and mountain climbers.

The sickle cell gene is inherited. One in 12 African-Americans carries this gene, though other races carry it too. Having two genes can be life-threatening, but having just one gene, the so-called trait, can protect against malaria.

While having the trait generally doesn't pose any problems, heat, dehydration, altitude and asthma can increase the risk of sickling.

Normally, oxygen-carrying red blood cells are round in shape. But for people with sickle cell, they become sickle shaped. This causes a log jam in blood vessels, and when deprived of their blood supply, organs can die.

Clark missed half of the 2007 season. He lost 30 pounds, and his spleen and gall bladder.

He lost the spleen because of its many tiny blood vesels and the gall bladder because of gall stones from the rapid breakdown of blood.

Other athletes are known to have the trait, but aren't affected as severely. Other blood disorders can make the problems with sickle cell trait worse, but generally, why there is such variability isn't yet known.

"You could possibly inherent two conditions like that, just to give you an example," says Dr. Krishnamurti. "These are just among the ones that we know. And what we know is a very small part of the entire body of what there is to know. There's a lot of other variations that could be there."

For athletes with sickle cell trait, it's a balancing act of pushing themselves to the limit and using common sense.

"If it's the first month of training and you're not already conditioned and it's really hot, maybe we don't train today, and you live to train another day," explains Dr. Krishnamurti.