However, I feel qualified to discuss such issues because I am a nephrologist and have treated patients with kidney disease for over 40 years, and have also performed extensive research on the handling of water by the kidneys.
Kane’s article unfortunately fails to accurately describe Obama’s campaign but, more unfortunately, also attempts to describe benefits of water-drinking in patients with kidney disease when such recommendations are actually potentially harmful.
Kane assumes that Obama recommended drinking water instead of sugary beverages. While that might be a rational approach to those seeking to reduce caloric intake, that is neither what she told her audience nor what she recommends.
For whatever political reason (perhaps to avoid the kerfuffle that occurred in New York City over Mayor Bloomberg's attempt to restrict soda intake), Obama only mentioned the supposed benefits of water-drinking.
Extensive research has failed to support her statements about water improving energy, ability to concentrate or much else. These are urban myths and have been shown to be unfounded.
Kane also states, “If our choices were a soda pop or a bottle of water, what would our kidneys, not Stanley Goldfarb, tell us is a better choice?” I can assure Kane that our kidneys have no particular opinion and turn all extra fluids we consume into urine.
Obama’s recommendation will only lead to more trips to the urinal.
Kane also chose to share his medical history with us and used it to advocate water-drinking to improve kidney function. This is simply wrong, and confuses several complex issues about various forms of kidney disease.
The insertion of tubes to drain the blocked ureters that Kane describes allowed his kidney function to improve, not his consumption of fluid. Once foreign material is in the urinary tract, we do encourage our patients to consume a high fluid intake, and we make the same recommendations following the chemotherapy he describes. This is to prevent bladder damage in the latter case and kidney stone formation in the former.
It is also true that patients who are very ill from vomiting can become fluid-depleted and require intravenous treatment, but this does not mean that normal individuals consuming extra water have improved kidney function.
In fact, careful studies show that drinking extra water rapidly may actually impair the kidneys’ ability to filter blood. Moreover, in the best study of the impact of extra fluid intake in patients with renal disease as conducted under the auspices of the National Institutes of Health, patients with chronic kidney disease who drank more fluids actually had a more rapid deterioration of kidney function than those consuming more typical volumes of fluid.
Hence, kidney specialists do not recommend forcing fluids in patients with kidney diseases unless there are very specific circumstances, like recurrent kidney stones.
The benefit or harm of extra water intake continues to be studied and new data are always forthcoming, but there are no data to recommend increased water intake as either a public health measure, and certainly not as a specific treatment for advanced kidney disease.
Kane does a disservice in using anecdotes to advance his personal view of a complex subject that is beyond his expertise.Stanley Goldfarb is professor of medicine and associate dean for curriculum of the University of Pennsylvania's Perelman School of Medicine.