Letters Section Editor: Stephen J. Lurie,
MD, PhD, Senior Editor.
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.
Hense HW. Blood Lead Levels and Hypertension. JAMA. 2003;290(4):460. doi:10.1001/jama.290.4.460-a