Isoleucine is an essential branched-chain amino acid. Isoleucine is involved in the regulation of energy balance and blood sugar levels, as well as hemoglobin synthesis. It is also needed for stimulating immune function, regulating hormone secretion, wound healing and detoxification of waste products. Increased blood isoleucine concentrations have been observed in diabetes mellitus and decreased concentrations in hepatic failure, as well as during inadequate protein intake. It is a heat-sensitive molecule, and its concentration rises after 24 hours of sample storage at room temperature.