Erythropoietin response to critical illness.

OBJECTIVE: To examine the endogenous erythropoietin response in critically ill children with acute anemia or acute hypoxemia.
DESIGN: A prospective case study of critically ill acutely anemic, and acutely hypoxemic pediatric patients compared with control groups of critically ill nonanemic and nonhypoxemic patients and with a hemoglobin and age-matched, chronically anemic patient group.
SETTING: Multidisciplinary, tertiary, pediatric intensive care unit (ICU). PATIENTS: Critically ill patients admitted to the pediatric ICU during an 11-month period between February 1992 and March 1993 with acute anemia (n = 21), acute hypoxemia (n = 18), or neither anemia nor hypoxemia (n = 10). Outpatients with chronic anemia (n = 21) and no acute illness were also studied as a comparison group.
INTERVENTIONS: None.
MEASUREMENTS AND MAIN RESULTS: Ages were equivalent among the groups and averaged 57.4 +/- 47.2 months (range 1 to 144). Acutely hypoxemic and critically ill control patients had normal hemoglobin levels. Acutely anemic patients had a hemoglobin level equivalent to chronically anemic outpatients, but lower (p < .001) hemoglobin levels than acutely hypoxemic and critically ill control patients. The serum erythropoietin concentrations in the acutely anemic group were significantly lower than erythropoietin values in the chronically anemic group (39.3 +/- 62.2 vs. 861 +/- 758 mU/mL, p < .001) and similar to erythropoietin concentrations in the critically ill control (13.5 +/- 10.5 mU/mL) and acutely hypoxemic (5.2 +/- 3.3 mU/mL) patient groups. Only ten of 49 critically ill patients had an erythropoietin concentration above normal, compared with 20 of 21 chronically anemic patients, whose erythropoietin concentrations were above normal.
CONCLUSIONS: The erythropoietin response to known physiologic stimuli is blunted in critically ill children. This blunted erythropoietin response may result in increased transfusion requirements.