A human blood protein has been found to be associated with the H7N9 fatality rate, according to a study by Chinese medical scientists.

The study, published in Nature Communications on Tuesday, showed that blood plasma levels of angiotensin II are higher in H7N9 patients and could be used to predict their physical deterioration.

Angiotensin II is a human protein contained in plasma, the vascular wall, heart and kidney to regulate blood pressure. It is closely linked to acute lung injury.

H7N9 patients with higher levels of angiotensin II carry more viral load, said Li Lanjuan, researcher at the Chinese Academy of Engineering and a specialist in H7N9 prevention.

"It is particularly obvious in the second week of human infection. The angiotensin II level of patients in critical condition keeps going up, while that of mild cases tends to drop," Li said.

Li added the new finding could help in clinical practice. Medical personnel could adopt more effective and reliable treatment measures for patients suffering different conditions.