Glutamine Test

Glutamine is the most abundant amino acid in the human body. Although it is technically classified as “nonessential” because the body can make it, it becomes “conditionally essential” during times of stress, illness, or injury. In those settings, the demand for glutamine outpaces the body’s ability to produce it, and tissue health may depend on additional supply.

Glutamine serves as a versatile fuel source and building block. It transports nitrogen, provides energy for rapidly dividing cells, and is a precursor for other amino acids such as arginine. Immune cells rely heavily on glutamine for proliferation and cytokine production, which are signals that help coordinate immune responses. Similarly, intestinal cells use glutamine as their preferred fuel, making it essential for maintaining gut barrier integrity and function. Beyond these roles, glutamine supports acid–base balance in the kidneys, contributes to antioxidant production through glutathione, and serves as a precursor for neurotransmitters.

Clinical research has examined glutamine supplementation in many contexts. In patients experiencing trauma, surgery, or sepsis, glutamine can improve nitrogen balance and may reduce complications, although results are mixed and not always definitive. In cancer, the situation is complex: while some tumors rely on glutamine metabolism for growth, healthy tissues also need glutamine to function, making supplementation a double-edged sword.

Glutamine is generally considered safe when taken short-term and at moderate doses. Clinical studies show no significant toxicity in healthy people or in patients, and it is FDA-approved for reducing painful crises in sickle cell disease. Still, not all conditions show benefit, and evidence in critical illness or chronic disease remains inconsistent. This is partly because it is not always clear when glutamine deficiency is truly present.