Anemia associated with inflammation commonly occurs with chronic states of exposure to infection or trauma. Several chronic conditions, including obesity, can also cause inflammation. The consequences of this phenomenon, commonly termed anemia of inflammation, include a reduction in the absorption of micronutrients, and/or temporarily isolating the micronutrients, which prevents the body from using them (see Micronutrient Deficiency section). In the short term, any detrimental changes will probably be minimal, but it will become a problem when exposure to infection/inflammatory stimuli is prolonged. An example of such a state is a condition called environmental enteropathy, a poorly defined state of intestinal inflammation, without obvious diarrhea, that occurs in individuals exposed to long-term poor sanitation and hygiene. They are repeatedly exposed to environmental pathogens, resulting in a chronic state of inflammation (Ngure et al. 2014; Petri, Naylor, and Haque 2014).
How is inflammation measured?
The two acute-phase-proteins C-reactive protein (CRP) and alpha-1-acid glycoprotein (AGP) are the most commonly used biomarkers to identify the presence of inflammation in nutrition surveys. CRP is a positive acute-phase protein that helps detect inflammation in its early stages. In the first six to eight hours of an inflammatory response, CRP levels increase rapidly, peaking within 24–48 hours (WHO 2014). AGP, also a positive acute-phase protein, is useful in detecting the later stages of inflammation, because it rises more slowly and takes three to five days to stabilize (Thurnham and McCabe 2012). A venous or capillary blood sample can measure CRP and AGP levels and a cold chain is required. Several laboratory techniques can be used; the most common is an enzyme-linked immunosorbent assay (ELISA). Other methods, such as immunoturbidimetry or antibody-based nephelometric assays, are also used (WHO 2014).
How is inflammation categorized?
A definition for what constitutes a public health problem for inflammation has not been established. Using both CRP and AGP, you can distinguish between different stages of the inflammatory process: incubation (measured by elevated CRP concentrations, >5 mg/L), early convalescence (measured by elevated CRP and AGP concentrations, >1g/L), and late convalescence (measured by elevated AGP only) (Thurnham and McCabe 2012).
Where can we get these data?
CRP and AGP are measured in population-based surveys and research studies conducted with women of reproductive age and children. Of the commonly administered population-based surveys, the National Micronutrient Survey is usually the only one that collects and analyzes information on the prevalence of inflammation.
Methodological issues
- As explained in the Iron Deficiency and Vitamin A Deficiency sections, determining the prevalence of inflammation by measuring AGP and CRP, and subsequently using these results to adjust the values of iron and vitamin A biomarkers, is a key step to obtaining a more accurate prevalence of micronutrient deficiencies.
- In women, the acute phase proteins may be higher in the late stages of pregnancy and early postnatally. A specific cut-off has not been developed for this population (WHO 2014).
Interventions that address inflammation
- case management of malaria
- clean play spaces
- deworming for schistosomiasis
- deworming for soil-transmitted helminths
- handwashing
- indoor residual spraying
- intermittent preventive treatment during pregnancy
- long-lasting insecticide-treated bed nets
- promotion of food safety
- use of basic and safely managed sanitation facilities
- use of safely managed drinking water services
- water treatment.
For more information about these interventions, go to the Step 4: Assess Status of Anemia Interventions section.