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Title: Pulmonary Hypertension May Indicate Hemoglobinuria: Presented at ASH

"Pulmonary Hypertension May Indicate Hemoglobinuria: Presented at ASH"

By Mike Fillon ATLANTA, GA -- December 15, 2005 -- A new study shows that pulmonary arterial hypertension (PHT) may be a common condition in patients with paroxysmal nocturnal hemoglobinuria (PNH). Results of the study were presented here on December 10[^th at the 47^th Annual Meeting of the American Society of Hematology (ASH).

In pulmonary hypertension the blood vessels narrow and their walls thicken, reducing the amount of blood they can carry. The narrowing causes blood pressure in the lungs to increase and forces the heart to work harder. Patients become tired, dizzy, and short of breath, particularly during exertion.

Patients with PNH -- a blood disorder characterized by the onset of severe hemolytic anemia, chronic fatigue, and intermittent episodes of dark colored urine, known as hemoglobinuria -- frequently suffer from shortness of breath.

Researcher Peter Hillmen, MB, ChB, PhD, consultant hematologist, General Infirmary, Leeds Teaching Hospitals, Leeds, United Kingdom, and colleagues examined the presence of PHT in patients with PNH and explored potential mechanisms associated with its development.

The study's results show that 50% of 28 patients with hemolytic PNH demonstrated PHT as defined by echocardiographic examination with a tricuspid regurgitant jet velocity (TRV) of 2.5 m/sec or greater. Two patients had moderate/severe PHT, with TRVs of 3.5 and 3.8 m/sec.

When the researchers compared plasma nitric oxide consumption in the 28 PNH patients and in 9 normal volunteers, they found a mean consumption of 34.6 mcM in the PNH patients and 2.12 mcM in the normal subjects (P < .0001).

Dr. Hillmen said the ability of patient plasma to deplete nitric oxide showed a highly significant correlation with the degree of hemolysis as measured by levels of lactate dehydrogenase (R = 0.63; P = .0002).

"PNH patients frequently have symptoms consistent with both anemia and pulmonary hypertension, including fatigue and dyspnea upon exertion," Dr. Hillmen said. "These results could alert physicians to the possibility of pulmonary hypertension as a potential cause of morbidity in patients with PNH."

Alexion Pharmaceuticals, Inc. provided partial funding for the study.

[Presentation title: Nitric Oxide Consumption and Pulmonary Hypertension in Patients With Paroxysmal Nocturnal Hemoglobinuria. Abstract 1046]

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