Hemoglobin level is positively associated with blood pressure in a large cohort of healthy individuals.

It has been hypothesized that an increased hemoglobin level elevates blood pressure. The present study investigated the association between hemoglobin level and systolic blood pressure and diastolic blood pressure in healthy persons. The study population was composed of 101 377 whole blood and plasma donors, who made 691 107 visits to the blood bank. At each visit, hemoglobin level and blood pressure were measured as part of the standard procedure before a blood donation. We used repeated measurement analysis to analyze the data. We used generalized estimating equation models to assess the between-person effect and linear mixed models to assess the within-person effect. All of the analyses were done separately for men and women. In the study population, 50% were men. The mean age in men was 49.3 years (±12.5 years), and in women it was 42.4 years (±13.7 years). Hemoglobin level was positively associated with both systolic and diastolic blood pressures. With respect to the between-person effect, regression coefficients for systolic blood pressure were 1.3 mm Hg per millimole per liter increase in hemoglobin level for men and 1.8 mm Hg per millimole per liter increase in hemoglobin level for women. With respect to the within-person effect, regression coefficients for systolic blood pressure were 0.7 mm Hg and 0.9 mm Hg per millimole per liter increase in hemoglobin level, for men and women, respectively. For diastolic blood pressure, results were comparable. The results show that hemoglobin level is positively associated with both systolic and diastolic blood pressures in healthy individuals. We observed consistent effects between persons but also within persons.