Age and sex trend differences in hemoglobin levels in China: a cross-sectional study

BACKGROUND: Both age and gender are the influence factors of hemoglobin concentration. However, the changing trend of hemoglobin levels between males and females with age remains unclear. This study aimed to explore their changing characteristics in different genders. METHODS: A cross-sectional study was conducted in Physical Examination Center of the First Affiliated Hospital of Wannan Medical College in Wuhu, China from 2014 to 2016. The generalized linear model was applied to explore the relationship between age, gender and hemoglobin levels. RESULTS: Among the 303,084 participants, the mean age for females and males was 46.9 ± 13.4(15–98) and 48.1 ± 13.7(14–98) years old, respectively. Generalized smoothing splines showed that hemoglobin levels increased up to age 25 and then decreased in men; in women the levels increased up until age 20, and then decreased, with slight increase again (β = 0.244, P < 0.01). After dividing all participants into hyperglycemia and normal groups, only the normal female group showed a significant upward trend (β = 0.257, P < 0.01) between ages 50–59. CONCLUSIONS: Hemoglobin concentration changes with age and the curve is different in males and females. The slightly upward trend of female hemoglobin in the age range of 50–59 years old should be considered in developing the reference range of hemoglobin making.