Researchers Estimate Hemoglobin Thresholds for Defining Anemia  – Renal and Urology News

Researchers estimated hemoglobin thresholds to define anemia in individuals aged 6 months to 65 years and found they are relatively consistent across diverse populations, according to findings published in The Lancet Haematology.

“[The World Health Organization’s] hemoglobin thresholds to define anemia are statistical thresholds reflecting the fifth centile of hemoglobin distribution in apparently healthy populations, set more than 50 years ago and maintained since then,” wrote the authors. “We sought to establish evidence for the statistical hemoglobin thresholds for anemia that can be applied globally and inform WHO and clinical guidelines.”

The researchers conducted an analysis of multiple international large-scale datasets in  8 ethnically diverse populations (USA, England, Australia, China, the Netherlands, Canada, Ecuador, and Bangladesh) with sufficiently detailed clinical and laboratory data to enable post-hoc assembly of reference populations of healthy individuals without discernible risk factors for anemia. These data were collected between 1998 and 2020. 

The team estimated hemoglobin thresholds based on fifth centiles for children aged 6-23 months, 24-59 months, and 5-11 years, adolescents aged 12-17 years, and adults aged 18-65 years, for individual and pooled datasets. They also evaluated findings from 3 large-scale genetic studies to identify genetic variants affecting hemoglobin concentrations in different ancestral populations.

In the pooled analyses, the hemoglobin fifth centile was 104.4 g/L (90% CI, 103.5-105.3 g/L) in children aged 6-23 months (n=924), 110.2 g/L (90% CI, 109.5-110.9 g/L) in children aged 24-59 months (n=1874), and 114.4 g/L (90% CI, 113.6-115.2 g/L) in children aged 5-11 years (n=1839). Thresholds were similar in males and females in these age groups.

In the pooled analyses, the hemoglobin fifth centile was 122.2 g/L (90% CI, 121.3-123.1 g/L) in female adolescents aged 12-17 years (n=1741), 128.2 g/L (90% CI, 126.4-130.0 g/L) in male adolescents aged 12-17 years (n=1103), 119.7 g/L (90% CI, 119.1-120.3 g/L) in non-pregnant female adults aged 18-65 years (n=3640), and 134.9 g/L (90% CI, 134.2-135.6 g/L) in male adults aged 18-65 years (n=2377). 

In pregnancy, the fifth centiles were 110.3 g/L (90% CI, 109.5-111.0 g/L) in the first trimester (n=772) and 105.9 g/L (90% CI, 104.0-107.7 g/L) in the second trimester (n=111). There was insufficient data to define a threshold for the third trimester. 

The investigators found no ancestry-specific, nonclinically relevant genetic variants that might contribute to variation in hemoglobin concentrations among diverse populations.

“In conclusion, this study provides an evidence base to harmonize hemoglobin thresholds to define anemia in children and adults worldwide and to inform global guidelines,” the authors wrote in their report. 

Limitations of the study included inability to estimate thresholds in children younger than 6 months, in pregnant patients during the third trimester, and among individuals aged >65 years due to lack of data. The determination was also based on statistical thresholds rather than functional thresholds, and there was a lack of data from other diverse populations, such as those from sub-Saharan Africa.

Disclosure: One study author declared affiliations with biotech, pharmaceutical, or device companies. Please see the original reference for a full list of authors’ disclosures. 

This article originally appeared on Hematology Advisor