Does Stress Place African American Youth at Greater Risk of Kidney Disease?

Newswise — African American youth may have greater changes to the kidney in response to stress than White youth do. Greater levels of urine microalbumin and lower levels of sodium excretion from the kidneys were found among African American youth compared to White youth who participated in a study presented today at ISHIB2006.

In their study, "Stress-induced pressure natriuresis is related to microalbumin in African American youth," Coral Hanevold, MD and colleagues examined impaired pressure natriuresis in response to stress (SIPN) and its relationship to urine microalbumin levels. SIPN has been found to be more common in African Americans than Caucasians and has been associated with changes in the heart and its function.(1) Other studies have linked impaired natriuresis (excretion of sodium in the urine) among adolescents with heart disease risk factors, including high blood pressure and obesity. (2)

Excessive urine microalbumin loss is considered to be an early indicator of kidney damage; kidneys that are functioning properly allow only very small amounts of albumin (a protein produced in the liver) to leak through into the urine. When a person's kidneys have become damaged, larger amounts of albumin (microalbumin) may leak into the urine. Dr. Hanevold's research demonstrates how urinary microalbumin excretion (UAE) was accompanied by changes in sodium excretion prompted by stress.

In their study, 276 healthy adolescents (189 African Americans and 87 Caucasians) participated in a 5-hour test. Each participant experienced one hour of mental stress preceded and followed by two-hour rest periods. Blood and urine samples were collected hourly and blood pressure readings were taken at 15-minute intervals.

The researchers found that, compared to the White youth, the African American youth had greater urine microalbumin, UAE (2.1±1 vs 2.4±1 mg/min), and less sodium excretion (4.5±6 vs 3.0±5 mEq/hr).

African Americans also had higher blood pressures throughout the duration of the test. "The results of our study show that, among some young African Americans, stress may lead to high blood pressure, which in turn, may influence kidney function," stated Coral Hanevold, MD, associate professor of pediatrics at the Medical College of Georgia in Augusta, Georgia, USA. "Over time, these processes could lead to permanent kidney damage."

These scientific findings were presented today at the 21st International Interdisciplinary Conference on Hypertension and Related Cardiovascular Risk Factors in Ethnic Populations as Abstract 016. The abstract appears below. Additional conference information and news from the conference can be found at http://www.ishib.org/ISHIB2006.

ISHIB2006 is jointly sponsored by ISHIB and the American Society of Hypertension (ASH). ISHIB (The International Society on Hypertension in Blacks) is a nonprofit, professional medical membership organization devoted to improving the health and life expectancy of ethnic populations. ISHIB was founded in Atlanta, Georgia, in 1986 to respond to the problem of high blood pressure among ethnic populations. Each year, its international interdisciplinary conference presents advancements in the treatment and prevention of cardiovascular diseases to reduce health disparities among ethnic minority populations. In addition to US conference locations, other sites for the conference have included Toronto, London, the US Virgin Island, Kenya, Cameroon, and Brazil.

References1. Harshfield GA, Wilson ME, Hanevold C, et al. Impaired stress-indeucted pressure natriuresis increases cardiovascular load in African American youths. Am J Hypertens. 2002;15(10 Pt1): 903-906.2. Rocchini AP, Key J, Bonde D, et al. The effect of weight loss on the sensitivty of blood pressure to sodium in obeses adolescents. N Engl J Med. 1989;312:580-585.