To the Editor: Dr Nash and colleagues1 reported that among women aged 40 to 59 years, higher blood lead levels were associated with risk of hypertension, particularly among postmenopausal women. Although the authors addressed several possible sources of residual confounding, they did not discuss the role of hematocrit levels.2 - 3 Even very low blood lead levels are affected by hematocrit levels because more than 95% of blood lead is bound to erythrocytes.4 Furthermore, we have found that hematocrit itself can be correlated with blood pressure, especially in women older than 50 years.2 Therefore, hematocrit levels may confound the association between blood lead and blood pressure and would result in overestimation of the association of blood lead with diastolic pressure, particularly in older women.
Furthermore, both red blood cell count and alcohol consumption have been found to covary with blood lead levels in their relationships with blood pressure.5 It would be interesting to know if the relationship between blood lead levels and hypertension in the study of Nash et al would be affected by including hematocrit and alcohol use in their analysis.
Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature
Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal
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