Normal BP pattern restored in kidney patients

NEW YORK (Reuters Health) - In "nondipper" patients with chronic kidney disease, individuals who don't experience the normal decline in blood pressure at night, changing the dose of one antihypertensive drug between morning and evening can restore the normal circadian rhythm, the results of a pilot study suggest.

Failure of blood pressure to drop by at least 10 percent at night is associated with an increased risk of developing cardiovascular and kidney complications, researchers in Italy note in the American Journal of Kidney Diseases. Nondipping status is highly prevalent in patients with chronic kidney disease, they add.

Dr. Roberto Minutolo and associates evaluated a "chronotherapeutic approach" among patients treated at the Nephrology Unit of the Second University of Naples. Included were 32 patients with chronic kidney disease, with a night-to-day ratio of average ambulatory blood pressure of more than 0.9, and normal blood pressure during the daytime.

The patients, who were taking an average of 2.4 antihypertensive medications each, were instructed to start taking one extra dose in the evening of any class of drugs, except diuretics.

After 8 weeks, the night-to-day ratio had decreased in 30 patients, and 28 patients achieved a normal dipping pattern of less than 0.9.

The average level of urinary protein excretion decreased significantly after the drug shift, from 271 milligrams per day to 182 milligrams per day, in correlation with the change in night-to-day blood pressure ratio.

The investigators observed no changes in body weight or two measures of kidney function -- the estimated glomerular filtration rate and daily urinary sodium excretion.

"The next logical question is whether lowering nocturnal blood pressure can retard the progression of chronic kidney disease and prevent cardiovascular complications," Dr. Mahboob Rahman, at Case Western Reserve University in Cleveland, and Dr. Lawrence J. Appel, at Johns Hopkins University in Baltimore, write in an accompanying editorial.

"The time is now ripe for a clinical outcomes trial of therapy that lowers nocturnal blood pressure," they add.

SOURCE: American Journal of Kidney Diseases, December 2007.