Estimation of the effect of the acute phase response on indicators of micronutrient status in Indonesian infants
Wieringa, F.T.; Dijkhuizen, M.A.; West, C.E.; Northrop-Clewes, C.A.; Muhilal
Journal of Nutrition 132(10): 3061-3066
2002
ISSN/ISBN: 0022-3166 PMID: 12368396 DOI: 10.1093/jn/131.10.3061Document Number: 247244
Many indicators of micronutrient status change during infection because of the acute phase response. In this study, relationships between the acute phase response, assessed by measuring concentrations of C-reactive protein (CRP), alpha 1-antichymotrypsin (ACT) and alpha 1-acid glycoprotein (AGP), and indicators of micronutrient status were analyzed in 418 infants who completed a 6-mo randomized, double-blind, placebo-controlled, supplementation trial with iron, zinc and/or beta -carotene. The acute phase response, defined by raised CRP (plasma concentration>10 mg/L), raised AGP (>1.2 g/L), or both raised CRP and AGP, significantly affected indicators of iron, vitamin A and zinc status, independently of the effects of supplementation. Plasma ferritin concentrations were higher by 15.7 (raised AGP) to 21.2 (raised CRP and AGP) micro g/L in infants with elevated acute phase proteins compared with infants without acute phase response (P<0.001). In contrast, plasma concentrations of retinol were lower by 0.07 (P<0.05, raised AGP) to 0.12 (P<0.01, raised CRP) micro mol/L, and of zinc lower by 1.49 (P<0.01, raised AGP) to 1.89 (P<0.05, raised CRP and AGP) micro mol/L. Hemoglobin concentrations and the modified relative dose response were not affected. Consequently, the prevalence of iron deficiency anemia was underestimated in infants with raised acute phase proteins by >15%, whereas the prevalence of vitamin A deficiency was overestimated by >16% compared with infants without acute phase response. Hence, using indicators of micronutrient status without considering the effects of the acute phase response results in a distorted estimate of micronutrient deficiencies, whose extent depends on the prevalence of infection in the population.