Possible mechanism underlying the association between higher hemoglobin level and hypertension in older Japanese men

Abstract

Aim: Hemoglobin is reported to be positively associated with hypertension. However, the underlying mechanism of this association is unknown. Recently, bone marrow-derived CD34-positive cells have been reported to play an important role in endothelial repair in conjunction with platelets. As the association between hypertension and endothelial dysfunction is bidirectional, the influence of endothelial repair also might strongly influence the association between hemoglobin and hypertension.

Methods: To clarify the clinical importance of the hematological parameter on endothelial maintenance in older men, we carried out a cross-sectional study of 222 Japanese men aged 60-69 years undergoing a general health checkup.

Results: For participants with a lower platelet count (≤21.0/μL), hemoglobin was significantly positively associated with hypertension, but not for participants with a higher platelet count (>21.0/μL). The classical cardiovascular risk factor adjusted odds ratio of hypertension for 1-standard deviation increment of hemoglobin (1.0 g/dL) was 2.09 (95% CI: 1.26, 3.48) for participants with a lower platelet count, and 1.07 (95% CI: 0.68, 1.67) for participants with a higher platelet count. We also found that although there was no significant correlation between hemoglobin and circulating CD34-positive cells for participants with a lower platelet count (β = -0.06, P = 0.603), a significant positive correlation was seen for participants with a higher platelet count (β = 0.29, P = 0.004).

Conclusions: The positive association between hemoglobin and hypertension was limited to participants with a lower platelet count as a result of insufficient endothelial repair. These results represent an efficient tool for clarifying the mechanism of endothelial maintenance that correlates with hypertension. Geriatr Gerontol Int 2017; 17: 2586-2592.

Keywords: CD34-positive cells; hemoglobin; hypertension; platelets; vascular maintenance.