Women have a "female advantage" when it comes to chronic kidney disease. When compared to men, they have fewer and less severe episodes of this disorder throughout most of their lives.
That advantage disappears, however, when the woman is diabetic. For reasons still unclear, diabetic women -- regardless of age -- are diagnosed with kidney and heart diseases almost as frequently as men.
What is it about diabetes that predisposes a woman to develop renal disease at levels generally associated with her male counterpart?
Researchers at Georgetown University's Center for the Study of Sex Differences in Health, Aging and Disease have been studying the phenomenon and have identified a novel observation to help explain why. The leader of this research team and the Center's Director of Diabetes Research is Dr. Christine Maric. She will discuss the state of the team's findings entitled, "Sex, Diabetes and Renal Injury," at the upcoming conference, Sex and Gender in Cardiovascular-Renal Physiology and Pathophysiology. The meeting, sponsored by the American Physiological Society is being held August 9-12, 2007 in Austin, TX.
Women are infrequently diagnosed with kidney or heart disease until they reach menopause. At menopause, when their sex hormone -- estrogen -- begins to disappear from their system, the rate of kidney disease begins to increase. As a result, estrogen is believed to have a protective effect against developing kidney and heart disease.
Unlike their non-diabetic counterparts of any age, women with diabetes are found to have similar rates of kidney and heart disease as males. Diabetic women are also known to have high rates of stillborn births, experience higher rates of menstrual difficulties, and have trouble conceiving.
In an effort to understand why women with diabetes are more likely to get kidney disease than their non-diabetic female counterparts, the Georgetown researchers conducted several studies in which they determined that:
- diabetes is associated with reduced estrogen (estradiol) levels, which may explain why the females lose the protective factor when it comes to diabetes
- estrogen and estrogen-like supplements protect the kidney in an animal model of diabetic renal disease, suggesting that restoring estrogen levels provides protection against kidney disease
- the absence of the hormone testosterone contributes to a more rapid progression of kidney disease when diabetes is present. More severe renal damage can be found when diabetes is present.
These findings suggest that sex hormones play a significant role in the development of diabetic kidney disease. According to Maric, "Our observations suggest that kidney disease in diabetic women may not be the result of absolute levels of hormones, as previously thought, but to the relative ratio of [sex hormone] androgen to estrogen. It may well be that the ratio of the two hormones is what determines the effect of the hormones in the diabetic kidney."
According to Dr. Maric, "The biggest surprise has been the finding that sex hormones -- normally thought to control only the reproductive function -- are involved in controlling processes in non-reproductive organs, including the kidney. Moving forward, we need to look more deeply into understanding how sex hormones affect organ function in each gender."
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