Transfer factor

Physiology · Respiratory physiology

The transfer factor describes the rate at which a gas will diffuse from alveoli into blood. Carbon monoxide is used to test the rate of diffusion. Results may be given as the total gas transfer (TLCO) or that corrected for lung volume (transfer coefficient, KCO)

Causes of a raised TLCO	Causes of a lower TLCO
asthma pulmonary haemorrhage (Wegener's, Goodpasture's) left-to-right cardiac shunts polycythaemia hyperkinetic states male gender, exercise	pulmonary fibrosis pneumonia pulmonary emboli pulmonary oedema emphysema anaemia low cardiac output

KCO also tends to increase with age. Some conditions may cause an increased KCO with a normal or reduced TLCO

pneumonectomy/lobectomy
scoliosis/kyphosis
neuromuscular weakness
ankylosis of costovertebral joints e.g. ankylosing spondylitis