The Acute Phase Response Affected Traditional Measures of Micronutrient Status in Rural Zambian Children during a Randomized, Controlled Feeding Trial
The acute phase response (APR) to infection can alter blood-based indicators of micronutrient status. Data from a 3-mo randomized, controlled feeding trial in rural Zambian children (n = 181, aged 3–5 y) were used to determine the impact of the APR on indicators of vitamin A and iron status using baseline and final blood samples. Concentrations of acute phase proteins were categorized as raised C-reactive protein (CRP; >5 and >10 mg/L) only, both raised CRP and α1–acid glycoprotein (AGP; >1.2 g/L), raised AGP only, and neither CRP nor AGP raised to identify the respective stages of infection: incubation, early convalescence, convalescence, and healthy state. Data were insufficient to examine the incubation stage of infection. A CRP concentration of >5 mg/L was an effective elevation cutoff point in this population to show impact on micronutrient markers. Time did not affect hemoglobin, serum ferritin, or serum retinol concentrations (P > 0.05). During early convalescence, hemoglobin decreased (14–16%; P ≤ 0.05), serum ferritin increased (279–356%; P ≤ 0.05), and serum retinol decreased (20–30%; P ≤ 0.05). Serum retinol concentrations did not change during convalescence; however, hemoglobin remained depressed (4–9%) and serum ferritin was elevated (67–132%) (both P ≤ 0.05). Modified relative dose response values were unaffected by the APR (P > 0.05) but increased between time points (16%; P ≤ 0.05), indicating a decrease in liver vitamin A reserves on the background of a semiannual vitamin A supplementation program. The observed prevalence of anemia and vitamin A deficiency assessed by serum retinol concentration was higher during the APR (P ≤ 0.05). It is important to consider the impact of infection on dietary interventions and to adjust for acute phase proteins when assessing iron status or vitamin A status by serum retinol concentration alone in children.
Bresnahan, K.A.; Chileshe, J.; Arscott, S.; Nuss, E.; Surles, R.; Masi, C.; Kafwembe, E.; Tanumidardjo, S.A. The Acute Phase Response Affected Traditional Measures of Micronutrient Status in Rural Zambian Children during a Randomized, Controlled Feeding Trial. Journal of Nutrition (2014) 144 (6) 972-978. [DOI: 10.3945/jn.114.192245]