Blood test detects sickle cell disease prognosis

High blood levels of an enzyme called lactate dehydrogenase (LDH) predict complications in patients with sickle cell disease, a disorder in which red blood cells cannot delivery oxygen properly because the cells have abnormal sickle shape, new research shows.

"Using modern technology, we reconfirmed that a very big source of LDH in the blood stream of patients with sickle cell disease is from the breakdown of red blood cells," not from the cell sickling itself, lead researcher Dr. Gregory J. Kato told Reuters Health.

"We also found that LDH can be a very convenient, inexpensive test for patients who are at high risk for certain sickle cell disease complications," he added.

LDH serves as a marker for "certain chemical reactions going on in bloodstream that depletes the patient of nitric oxide." Kato explained that nitric oxide normally works to open or dilate blood vessels. "When there is a deficiency of nitric oxide, the blood vessel walls become thickened in a way that narrows" the opening and leads to nitric oxide resistance.

Kato, from the National Institutes of Health in Bethesda, Maryland and his colleagues evaluated 213 patients with sickle cell disease. They report their findings in the medical journal Blood.

High LDH levels predicted elevated lung pressure, leg ulcers and a painful erectile condition called priapism. Moreover, patients with high LDH levels were at increased risk for death during the 49-month study.

For patients with high LDH levels, Kato recommends screening for evidence of high blood pressure in the lungs with echocardiography, a type of ultrasound. If high pressure is evident, several treatment options are available, including drug therapy and blood transfusions.

SOURCE: Blood, March 15, 2006.