Scientists at the National Heart, Lung, and Blood Institute (NHLBI) and investigators affiliated with the Multicenter Study of Hydroxyurea (MSH) Patients' Follow-Up theorized that the more strain the heart is under, the more BNP would be released. Therefore, they theorized that levels of BNP would be able to tell them which patients had pulmonary hypertension.

The researchers estimate that 10 years ago, almost one third of patients in the MSH Patients' Follow-Up had undiagnosed pulmonary hypertension, according to lead researcher Roberto Machado, MD, staff clinician, vascular medicine branch, NHLBI, and attending physician, critical care medicine department, National Institutes of Health Bethesda, Maryland.

Dr. Machado and colleagues measured BNP levels in 230 patients with sickle cell disease and in 45 healthy controls. BNP levels were higher in the sickle cell patients who had pulmonary hypertension than in patients without pulmonary hypertension or in the healthy controls. An abnormally high BNP level (> 160 pg/mL) was used as an indicator of pulmonary hypertension.

To confirm the finding independently, BNP levels were measured in banked blood samples of a separate cohort of 121 patients with sickle cell disease enrolled in the MSH Patients' Follow-Up study initiated in 1996. A high BNP level was found in 30% of these subjects and was associated with a high prospective risk of death. This measure was an independent predictor of future death even when controlled for other factors, such as the rate of pain episodes.

"Considering that pulmonary hypertension is common and a major risk factor for death in patients with sickle cell disease, a test that could be used to assess this risk is potentially helpful," Dr. Machado said. "This new predictor -- BNP -- adds to the inventory of screening tests that could be used to identify pulmonary hypertension in patients with sickle cell disease."

Dr. Machado said the data also suggest that the greatest risk factor for death was not the frequency of painful crisis or the acute chest syndrome, but rather unrecognized pulmonary hypertension.


[Presentation title: Natriuretic Peptide Levels Correlate with Pulmonary Pressures and Prospective Mortality in SCD: Use of This Biomarker to Identify Prevalence and Mortality of Pulmonary Hypertension in the MSH Cohort. Abstract 1]

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