All patients who are admitted to the ICU after elective surgery and non-elective admissions. In both groups a total of 80 patients will be included.~(In the trials we mentioned in the introduction 80, 174 and 66 patients were included. In the study performed by Oudemans-van Straaten a decent distribution between lower and higher levels of glutamine was achieved in 80 non-elective patients.) Exclusion criteria are patients younger then 18 years and patients who need total parenteral nutrition (TPN).~The patients will receive standard care during their treatment on the ICU. Blood sampled for standard evaluation will be used for determination of plasma glutamine by Bioprofile Flex Glutamine Sensor at ICU admission. Hereafter plasma glutamine will be measured daily, a plasma sample will be taken from a standard evaluation blood sample at 6.00 am during admission on the ICU.
Blood sampled for standard evaluation will be used for determination of plasma glutamine by Bioprofile Flex Glutamine Sensor at ICU admission