Protein Predicts Sickle-Cell Danger

By Harder, Ben

PROGNOSTIC BIOMARKERS

A biological marker of heart trouble can be used to identify sickle-cell anemia patients who are at greatest risk of developing a serious complication.

Pulmonary hypertension-high blood pressure of the arteries in the lungs-puts stress on the heart and is a major cause of disability and death among sickle-cell patients. Doctors can diagnose pulmonary hypertension using an echocardiogram, but they have difficulty predicting which patients will develop it.

To try a different approach, Roberto Machado of the National Heart, Lung, and Blood Institute in Bethesda, Md., and his colleagues tested blood samples from 275 volunteers for B-type natriuretic peptide (BNP). In patients with other disorders, the heart is known to overproduce that protein when it has difficulty pumping.

In sickle-cell patients with pulmonary hypertension, the average BNP concentration was 206 picograms per milliliter (pg/ml). By contrast, average BNP was just 29 pg/ml in healthy volunteers and 46 pg/ml in sickle-cell patients who hadn’t developed the blood- pressure disorder, Machado’s team found.

To test BNP’s value as a prognostic tool, Machado’s team then measured the protein in blood samples taken in 1996 from 121 other sickle-cell patients. The researchers found that patients who had at least 160 pg/ml BNP in 1996 were three times as likely to have died by 2005 as patients with lower BNP levels were. -B.H.

Copyright Science Service, Incorporated Dec 24-Dec 31, 2005