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Re: confounding factors when defining the cut-off level for NT-pro BNP

Dear editor

The cut off level for NT-pro BNP proposed by the authors(1) should take into account the fact that blood levels of this parameter may be lower in subjects with body mass index equal to or exceeding 30 kg/metre squared despite left ventricular end diastolic pressures which exceed those of counterparts with lower body mass indices(2). Lower cut-off levels might then have to be devised in obese subjects. Polymorphism of the type B human natriuuretic peptide receptor gene(3) might well, theoretically, be another confounding factor in the evaluation of NT- pro BNP levels, given the fact that blood levels of this parameter depend, in part, on regulation of gene expression(4).

References

(1) Turley AJ., Roberts AP., Davies A et al NT-pro BNP and the diagnosis of left ventricular systolic dysfunction within two acute NHS trust catchment areas: the initial Teeside experience Postgrad Med J 2007:83:206-8

(2) Taylor JA., Christenson RH., Rao KJorge M., Gottlieb SS B-Type natriuretic peptide and N-terminal pro B-type natriuretic peptides are depressed in obesity despite higher left ventricular end-diastolic pressures Am Heart J 2006:152:1071-6

(3) Rahmutula D., Nakayama T., Soma M.,et al Systematic screening of type B human natriuretic peptide receptor gene polymorphisms and association with essential hypertension Journal of Human Hypertension 2001:15:471-4