RESUMO
It is unclear whether risk of infection is increased in individuals with hereditary haemochromatosis and in individuals with low or high plasma iron, transferrin saturation, or ferritin. Therefore, we tested whether high and low iron, transferrin saturation, and ferritin are associated with risk of infections observationally and genetically through HFE genotypes. We studied 142,188 Danish general population individuals. Iron, transferrin saturation, and ferritin were measured in 136,656, 136,599, and 38,020 individuals, respectively. HFE was genotyped for C282Y and H63D in 132,542 individuals. Median follow-up after study enrolment was 8 years(range:0-38years) for hospital and emergency room admissions with infections(n=20,394 individuals) using the National Patient Register, covering all Danish hospitals. Hazard ratios for any infection were 1.20(95%CI:1.12-1.28) and 1.14(1.07-1.22) in individuals with plasma iron≤5th or ≥95th percentile compared to individuals with iron from 26th-74th percentiles. Findings for transferrin saturation were similar, while infection risk was not increased in individuals with ferritin≤5th or ≥95th percentile. Hazard ratios in C282Y homozygotes versus non-carriers were 1.40(1.16-1.68) for any infection, 1.69(1.05-2.73) for sepsis, and 2.34(1.41-3.90) for death from infectious disease. Risk of infection was increased in C282Y homozygotes with normal plasma iron, transferrin saturation, or ferritin, and in C282Y homozygotes without liver disease, diabetes, and/or heart failure. In summary, low and high plasma iron and transferrin saturation were independently associated with increased infection risk. C282Y homozygotes had increased risk of any infection, sepsis, and death from infections. Even C282Y homozygotes with normal iron, transferrin saturation, or ferritin, not currently recommended for genotyping, had increased infection risk.
RESUMO
Hereditary spherocytosis (HS) is a common anemia caused by germline mutations in red blood cell cytoskeleton proteins. The flow cytometry-based eosin-5'-maleimide (EMA) binding test is most frequently employed for reliable diagnostics. To perform this test, a number of healthy and ideally also age-matched controls are required, which can be challenging and complicates interlaboratory comparisons. To overcome this limitation, we modified the EMA binding test by replacing healthy controls with commercially available fluorescent beads. Blood samples from 289 individuals with suspected HS were analyzed using the EMA binding test with fluorescent beads and benchmarked against regular EMA binding test using two control samples. Using osmotic gradient ektacytometry as validation, 112 individuals (38.8%) were diagnosed with HS. Performance of the modified EMA binding test was not compromised (accuracy 90.3%) compared to EMA binding test using matched controls (accuracy 88.6%). Based on these findings, we conclude that the modified EMA binding test with fluorescent beads is an attractive alternative, especially in laboratories without easy access to matched controls. Furthermore, as fluorescent beads are stable and easily commutable, they could facilitate both interlaboratory comparisons and quality assessment programs.
