Quantitation of gastrointestinal protein loss

Plasma proteins leak into the gastrointestinal tract under physiological conditions. This may assume enormous proportions in certain pathological conditions associated with the stomach, intestines, intestinal lymphatics and capillaries, resulting in severe hypoproteinemia. Quantitation of this leakage has been achieved by using plasma proteins or non-protein foreign colloids and macromolecules labelled with radioactive isotopes. The requirements of an ideal label have been listed and the advantages/disadvantages of different tracer labels have been reviewed. No label presently available fulfils all the requirements of an ideal tracer. In spite of this, a wealth of information has been acquired by gastroenterologists to unravel the mystery of hypoproteinemia of unknown cause.