TTR and infection: Additionally, infection itself can compromise vitamin A status in number of ways.41 Vitamin A is excreted in the urine in patients with fever and this has been confirmed in subjects with acute infection including pneumonia.42 During the acute phase response, leakage of proalbumin through the vascular endothelium occurs; and production of retinal binding proteins and prealbumin by liver is reduced.41 In addition, requirement of vitamin A during infection is raised by its increased rate of excretion and metabolism.42