trauma and severe infections cause remarkable metabolic changes in patient with SIRS from an adaptive response aimed to control the underlying disease, repairing damaged tissue, and to synthesize substrates. If the attack is intense and sustained and the patient has a compromised nutritional status, can evolve into multiple organ failure and death. assessment of nutritional proteic status and the involvement of proteins and inflammatory factors in critically ill patients. multicenter observational analytical study in critical ill patients at the admission in ICU. patients showed disturbances in clinical nutritional parameters which confirm their hypercatabolic situation, showing malnutrition state at admission, where 42.9% had plasma levels below the reference prealbumin. Amino acid profile was situated below the reference values and 99% of patients had low plasma transferrin. Significant differences were observed in total protein, ferritin and transferrin parameters adjusted by CRP levels, being higher when patients presented high inflammation in the case of ferritin and the opposite for the rest of parameters. Adjusting APACHE and SOFA scores according to low, medium and high severity, results showed significant differences in creatinine, urea, and transferrin, being lower at high severity grade for the last one. critical illness is characterized by a high degree of stress and accelerated degradation of proteins that cause malnutrition, systemic inflammation and organ dysfunction, with a significant association between albumin, ferritin and transferrin.