Consider renal effects of high-protein diets.
Chronic kidney disease is often silent, so he recommends obtaining a serum creatinine measurement and a urinary dipstick test for proteinuria in all patients considering a high-protein diet for weight loss.
Those with a glomerular filtration rate less than 60 mL/min should be advised against a high-protein diet, said Dr. Friedman of Indiana University in Indianapolis.
Regardless of kidney function, protein intake increases glomerular filtration rate and renal blood flow by as much as 100% from baseline.
Over time, a high-protein diet appears to increase kidney volume and weight.
Studies suggest that high-protein diets increase urinary protein excretion in people with normal and in those with diminished kidney function, Dr. Friedman said.
High-protein diets are intended to induce ketosis by limiting carbohydrate intake. Increased ketone levels lead to increased sodium output, which in turn induces natriuresis, he said.
In the short-term, high protein consumption has been associated with orthostatic hypotension.
There is little evidence that high-protein diets maintained for months adversely effect blood pressure, compared with standard low-fat diets.
Animal and human studies have shown that increased protein consumption leads to hyperuricosuria, hypercalciuria, hypocitraturia, and areduction in urinary pH--all risk factors for the formation of kidney stones.
Healthy patients that are considering a high-protein diet should be advised about the potentially deleterious effects: chronic glomerular hyperfiltration and hyperemia, increased proteinuria, and an elevated risk for nephrolithiasis, Dr. Friedman said.
It may be helpful, he added to point out to patients that although short-term studies (3-6 months) have resulted in more weight loss for high-protein diets than for standard diets, long-term studies (up to 1 year) have shown no differences in weight loss between the two groups.
BY KERRI WACHTER
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|Title Annotation:||Clinical Rounds|
|Publication:||OB GYN News|
|Date:||Jul 1, 2005|
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