Using plasma acute-phase protein concentrations to interpret nutritional biomarkers in apparently healthy HIV-1-seropositive Kenyan adults

Abstract

Inflammation influences the assessment of nutritional status. For example, inflammation reduces plasma retinol concentrations and vitamin A deficiency is overestimated. Conversely inflammation increases plasma ferritin concentrations and Fe deficiency is underestimated. Blood samples were obtained from 163 free-living HIV-1-infected adults, not on continuous medication, anti-retroviral drugs or micronutrients, not unwell and who had not reached WHO stage IV of HIV/AIDS. We used four markers of inflammation, C-reactive protein (CRP), a1-acid glycoprotein (AGP), a1-antichymotrypsin and erythrocyte sedimentation rate but mainly CRP and AGP were used to separate the subjects into four groups: 'healthy' where both CRP and AGP were normal; 'incubation phase' where CRP was elevated; 'early convalescence' where AGP and CRP were elevated and 'late convalescence' where only AGP was elevated. Correction factors were calculated to remove the influence of inflammation from each biomarker and group where inflammation was present and the data are shown before and after recalculation. The correction increased median plasma retinol concentrations of the whole group from 1·16 to 1·33 mmol/l, comparable with values (mean 1·29 mmol/l) in HIV-negative Kenyan women. Median ferritin concentrations fell by about 50 % in both sexes and the number of women with plasma ferritin concentrations #12 mg/l increased from eleven to twenty. The correction also increased plasma carotenoids and Hb but not a-tocopherol concentrations. We suggest that the method described to remove the influence of inflammation from nutritional biomarkers should be generally applicable in apparently healthy people and prevents discarding valuable data because of mild inflammation. The method does now need to be tested in other populations.

Interactions between nutrition and immune function: using inflammation biomarkers to interpret micronutrient status

“…Percentage changes were calculated using the uncorrected and corrected median values for the men (488, 166) and women (90, 41 μg/l), respectively. Data taken from (11,31) . Data are medians (25th, 75th quartiles; percentage of change) of the changes in ferritin between baseline and 3 months.…”

Assessment and interpretation of micronutrient status during pregnancy

“…High serum ferritin can also result from damage to ferritin-rich tissues that releases it into the maternal circulation, such as can occur in cases of pre-eclampsia (66) . Inflammation and infection tend to affect the entire serum ferritin distribution, not just those individuals with high concentrations (67) and therefore, whenever possible, serum ferritin should be measured alongside inflammatory markers such as C-reactive protein, a1-antichymotrypsin, a1-acid glycoprotein or erythrocyte sedimentation rate (68,69) . The relationship between serum ferritin and pregnancy outcome is confounded by several of the same factors that complicate the assessment of anaemia.…”

Correcting for Inflammation Changes Estimates of Iron Deficiency among Rural Kenyan Preschool Children

“…In areas where there are high rates of inflammation, exclusion of a large number of people may be impractical (6,(10)(11)(12)(13). The use of CF incorporates the effects of the APP on iron status indicators, information that is not fully captured by simply modifying the cutoff point for ferritin.…”