title: Erythropoietin mimics the acute phase response in critical illness.
abstract: BACKGROUND
  In a prospective observational study, we examined the temporal relationships between serum erythropoietin (EPO) levels, haemoglobin concentration and the inflammatory response in critically ill patients with and without acute renal failure (ARF).
  
  
  METHODS
  Twenty-five critically ill patients, from general and cardiac intensive care units (ICUs) in a university hospital, were studied. Eight had ARF and 17 had normal or mildly impaired renal function. The comparator group included 82 nonhospitalized patients with normal renal function and varying haemoglobin concentrations. In the patients, levels of haemoglobin, serum EPO, C-reactive protein, IL-1beta, IL-6, serum iron, ferritin, vitamin B12 and folate were measured, and Coombs test was performed from ICU admission until discharge or death. Concurrent EPO and haemoglobin levels were measured in the comparator group.
  
  
  RESULTS
  EPO levels were initially high in patients with ARF, falling to normal or low levels by day 3. Thereafter, almost all ICU patients demonstrated normal or low EPO levels despite progressive anaemia. IL-6 exhibited a similar initial pattern, but levels remained elevated during the chronic phase of critical illness. IL-1beta was undetectable. Critically ill patients could not be distinguished from nonhospitalized anaemic patients on the basis of EPO levels.
  
  
  CONCLUSIONS
  EPO levels are markedly elevated in the initial phase of critical illness with ARF. In the chronic phase of critical illness, EPO levels are the same for patients with and those without ARF, and cannot be distinguished from noncritically ill patients with varying haemoglobin concentrations. Exogenous EPO therapy is unlikely to be effective in the first few days of critical illness.
authors.affiliation: University Department of Anaesthesia and Intensive Care, Queen Elizabeth Hospital, Birmingham, UK. michael.elliot@goodhope.nhs.uk
authors.forename: John Michael
authors.initials: JM
authors.lastname: Elliot
authors.forename: Tanit
authors.initials: T
authors.lastname: Virankabutra
authors.forename: Stephen
authors.initials: S
authors.lastname: Jones
authors.forename: Surasak
authors.initials: S
authors.lastname: Tanudsintum
authors.forename: Graham
authors.initials: G
authors.lastname: Lipkin
authors.forename: Susan
authors.initials: S
authors.lastname: Todd
authors.forename: Julian
authors.initials: J
authors.lastname: Bion
mesh_terms: D058186:Acute Kidney Injury / Q000097:blood* / Q000150:complications*; D000210:Acute-Phase Reaction / Q000097:blood* / Q000209:etiology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D001803:Blood Transfusion; D016638:Critical Illness; D004921:Erythropoietin / Q000097:blood*; D005260:Female; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007249:Inflammation / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D008297:Male; D008875:Middle Aged; D010045:Outpatients; D011446:Prospective Studies; D012016:Reference Values; D013995:Time
chemical_list: D015415:Biomarkers; D006454:Hemoglobins; D015850:Interleukin-6; D004921:Erythropoietin