The risk of hypertension increases in people who have a higher level of urinary albumin excretion even if it is within the normal range.
Kidneys normally prevent large molecules such as albumin from being excreted in the urine, but high levels of urinary albumin excretion, called albuminuria can be an indicator of kidney damage.
Albuminuria may also reflect dysfunction of endothelial cells throughout the body, which in turn may be a precursor to hypertension.
The study suggests that to prevent cardiovascular disease, the definition of "normal" urinary albumin excretion should be reconsidered.
For the study, Dr. John Forman and colleagues at the Brigham and Women's Hospital in Boston, MA, looked at the new development of hypertension among 2,179 women without baseline hypertension or diabetes, and with normal levels of urine albumin, who were a part of Nurses' Health Studies.
The findings showed that that higher levels of urinary albumin excretion, even within the range considered normal, increased an individual's risk of developing hypertension.
They found that the older women (median age of 65 years), with increased levels of albumin excretion had 76 pct greater risk of developing hypertension than those with the lowest levels.
And for younger women with median age of 44 years, the risk was 35 pct. higher.
The authors suggest, "It is time to re-evaluate our current concept of 'normal' albumin excretion."
The study will appear in the October 2008 issue of the Journal of the American Society Nephrology (JASN).