Distortion of iron status indices by acute inflammation in older hospitalized patients

Abstract

The relation between acute inflammation and biochemical indices of iron and nutritional status in older in-patients have been investigated. Thirty-nine consecutive patients (25 men and 14 women; median age 79 years) with acute inflammation episode were evaluated. C-reactive protein (CRP) > or = 3 mg/dl was considered to indicate acute inflammation. Iron and nutritional status were explored measuring hemoglobin (Hb), hematocrit (Ht), red blood cell (RBC), white blood cell (WBC), mean erythrocyte volume (MCV), mean corpuscular hemoglobin (MCH), and serum levels of iron (Fe), transferrin (T), percentage transferrin saturation (%TS), ferritin (SF), albumin (Alb) and pre-albumin (pre-Alb), the day after admission (T-basal), the day of onset of inflammation (T0), and successively (T5, T8-15, and T-final). CRP and WBC were significantly higher at T0 than T-basal (CRP: +1014%, P < 0.01; WBC: +30%, P < 0.01) but had reduced on days T8-15 compared to T0 (CRP: -90%, P < 0.01; WBC: -26%, P < 0.01). Fe serum levels fell at the beginning of the acute phase (T0: -24% versus T-basal; P < 0.01), but had recovered at T-final (+36% versus T5; P < 0.01). T levels also varied significantly (P < 0.01) (T0: -16% versus T-basal; T-final: +18% versus T5). SF was slightly higher than normal at T-basal and increased further during inflammation (+41% at T5 versus T-basal) to reduce at T-final (-36% versus T5; P < 0.01). At T-final, pre-Alb and Alb were significantly higher than at T5 (pre-Alb +63%, P < 0.01; Alb +20%, P < 0.05). The indices of iron status are disrupted in elderly patients during acute inflammation, just as they are in chronic inflammation, and cannot therefore be used to diagnose sideropenic anemia. The only variables not influenced by inflammation are MCV and %TS. Low values of these, associated with other symptoms of anemia, suggest sideropenic anemia, irrespective of the values of the other indices of iron status. With the appearance of inflammation, nutritional indices tend to decline as liver activity shifts to the production of acute phase proteins.