An observational study to determine the optimal physical evaluation site for detecting anemia

Clinical pallor has traditionally served as a screening tool for anemia; however, its assessment lacks objectivity. Therefore, this study aimed to investigate the correlation between skin and mucosal color, as measured by a spectrophotometer, and venous hemoglobin (Hb) values, to identify the optimal anatomical assessment site for detecting anemia.

A cross-sectional design. Ninety-two adult Japanese outpatients participated in the study. Using a spectrophotometer, the color of the lip and conjunctiva was measured indirectly, while the color of the nail, palm, and inside of the upper arm was measured directly. Colors were quantified using the L*a*b* color scale. This is an international color scale, where the L* value is an index of brightness, a* value is red/green, and b* value is yellow/blue. The color difference (Δ E*) was employed to evaluate the discriminability of anemia identification across different assessment sites. Additionally, Hb values were recorded, with anemia defined as Hb <12.0 g/dL.

The a* values of the lip, conjunctiva, palm, and arm exhibited a positive correlation with Hb values and were significantly lower in the anemic group. While the Δ E* levels for the conjunctiva and lip were readily discernible by the human eye when comparing the normal and anemic groups, recognition at this level proved challenging for other sites.

The conjunctiva and lip demonstrate potential suitability for visual diagnosis of anemia. In the nail, palm, and arm, anemia detection may require highly trained observation. Consequently, reliance on these sites for anemia diagnosis may lead to potential oversight.