Urologic Diseases Research Updates
Lower Urinary Tract Symptoms in Men Associated with Metabolic Syndrome
Men with mild to severe lower urinary tract symptoms (LUTS) are more likely to have metabolic syndrome (MetS)-a constellation of cardiovascular disease risk factors-than men without them, according to an analysis of data collected by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)-funded Boston Area Community Health (BACH) survey.
"These findings have important diagnostic and management implications. Patients who present with components of metabolic dysfunction should be routinely queried with respect to urological function," wrote Varant Kupelian, Ph.D., a research scientist at the New England Research Institutes, Watertown, MA, and co-authors in their report about the analysis, which appeared in the August 2009 issue of The Journal of Urology.
Interestingly, the prevalence of MetS was just as high among men with mild LUTS as it was among men with severe LUTS. Men with no LUTS had the lowest prevalence of MetS, but MetS prevalence quickly increased with increasing LUTS. The researchers scored LUTS severity using the American Urological Association Symptom Index (AUASI). See the table below for a description of the AUASI questionnaire.
MetS components include abdominal obesity, high blood pressure, high cholesterol, high triglycerides, and diabetes. Scientists believe these frequently comorbid conditions may stem from a common underlying cause. For the current analysis, MetS was defined as the presence of three or more MetS components.
Funded by the NIDDK, the BACH is a population-based epidemiological survey of urologic symptoms, such as pelvic pain, prostatitis, and sexual dysfunction, among men and women ages 30 to 79. From 2002 to 2005, BACH researchers interviewed study participants, asking extensive questions about health history; lifestyle; use of tobacco, alcohol, and medications, including diabetes medications; and level of income and education. They recorded participants' hip and waist circumference, height, weight, and blood pressure and collected blood for the analysis of cholesterol and triglycerides.
When LUTS were grouped as either "voiding" or "storage" symptoms, the researchers found that mild or worse voiding symptoms-incomplete emptying of the bladder, weak urine stream, intermittency (starting and stopping a urine stream), and straining to urinate-were significantly associated with MetS; however, storage symptoms were not. Urgency (the urgent need to urinate), frequency of urination, and nocturia (waking during the night to urinate) were grouped as storage symptoms. When researchers analyzed LUTS individually, they found that incomplete emptying, intermittency, and nocturia were all independently associated with increased odds of MetS.
LUTS are common among men. Between 26 and 46 percent of men ages 40 to 79 have moderate to severe LUTS. For years, scientists thought LUTS in men were principally related to the bladder and benign prostatic hyperplasia(BPH). But recent data pointing to associations between LUTS and chronic illnesses, such as heart disease and diabetes, have fostered the hypothesis that factors outside the bladder and prostate play an important role.
"This community-based cohort study confirms the results of prior analyses linking the metabolic syndrome to an increased risk of LUTS, and adds to a growing body of evidence supporting robust associations of modifiable risk factors-obesity, diabetes, and diet-with LUTS and BPH," wrote J. Kellogg Parons, M.D., an assistant professor at the University of California, San Diego, in a companion editorial.
Diabetes and LUTS
Diabetes was associated with more significant increases in LUTS than any of the other four components of MetS. Chronic hyperglycemia, or high blood glucose, resulting from diabetes is known to damage peripheral nerves.
In their report, the researchers suggest that the increase in voiding but not storage symptoms associated with MetS may be due to a phenomenon seen in animal studies that show that hyperglycemia selectively increases cell death of pelvic parasympathetic neurons but has little effect on sympathetic neurons.
"Such an unbalanced loss of autonomic neurons might induce an oversupply of sympathetic tone compared to parasympathetic efferent activity resulting in increased bladder neck obstruction and reduced bladder power, which combined might produce an increase in obstructive symptoms as noted," wrote Kupelian and colleagues.
The authors urged additional studies aimed at understanding the common pathophysiology of LUTS and MetS.
The National Kidney and Urologic Diseases Information Clearinghouse, an information dissemination service of the NIDDK, has fact sheets and easy-to-read booklets about urologic diseases. For more information or to obtain copies, visit www.urologic.niddk.nih.gov.
NIH Publication No. 10-5743