MedicalResearch.com Interview with:
Teodor Paunescu, PhD and
Sagar Nigwekar, MD
Division of Nephrology
Massachusetts General Hospital
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Over 25 million people in the U.S. have chronic kidney disease, and the number of deaths caused by this disease has doubled between 1990 and 2010. It is projected that by 2030 more than 1 in 3 adults over 65 years old will be diagnosed with chronic kidney disease.
Many patients with kidney disease are also malnourished, which negatively impacts their quality of life, overall health, and even survival. However, no effective treatments are currently available to address malnutrition in these patients.
The sense of smell plays an important role in determining food flavor. If a patient’s ability to smell is impaired, this could affect the taste of food, for example, foods that used to appeal to the patient may no longer do so. Given the relation between the sense of smell and appetite, we set out to investigate the loss of smell in patients with kidney disease, and to test an intervention aimed at alleviating their smell deficits.
Our first goal was to determine if patients with various degrees of kidney disease suffer smell losses and whether smell issues might affect their nutritional status. We found that, while most kidney disease patients do not perceive a problem with their sense of smell, deficits in the ability to smell are actually common among these patients, and the severity of these deficits increases with the severity of their kidney disease. Moreover, our study found that reductions in several markers of nutrition (such as cholesterol and albumin levels) correlate with the impairment in these patients’ sense of smell.
MedicalResearch.com: What should clinicians and patients take away from your report?
Response: To fully appreciate the flavor of food, one needs to have an intact sense of smell. If a patient’s ability to smell is reduced, this could lead to symptoms of food aversion and thus decreased food intake, which in turn would contribute to the patient becoming malnourished. For patients with kidney disease, malnutrition is a well-known complication, which causes poor quality of life, poor overall health, and even decreases their survival chances. Our study found that the majority of patients with kidney disease also have some degree of smell loss, and moreover, the worse their ability to smell, the worse their nutritional status is. We started testing whether theophylline (a medication currently used to treat asthma) can improve kidney patients’ ability to smell, and our preliminary results are indeed promising. Thus, there is reason to hope that the proposed treatment may improve not only the sense of smell, but also the patients’ nutritional status, quality of life, and survival.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Response: Our ultimate goal is to have an intervention that can alleviate smell loss, and thus to improve the kidney patients’ nutritional status. Our preliminary results show an improvement in the ability to smell in 5 out of 7 patients on dialysis in response to a drug currently used to treat asthma, warranting confirmation in a larger study.
MedicalResearch.com: Is there anything else you would like to add?
Response: Our study highlights smell loss as a novel mechanism to better understand malnutrition. Our data show that smell loss is an important determinant of nutritional status, although clearly not the only one. Despite our study notably including the largest number of patients compared to all previous investigations on this topic, the way in which it was designed does not allow one to attribute causality to the establishedassociations. A future study on patients with progressing kidney disease is needed to determine how the sense of smell and nutritional status worsen as kidney function deteriorates.
We were very excited to see that, according to the data from our pilot clinical trial, smell losses in patients with kidney disease are potentially reversible. However, most of our patients with advanced kidney disease were receiving in-center hemodialysis 3 times a week. Consequently, we cannot be certain at this point that our findings also apply to patients receiving peritoneal dialysis or to patients receiving hemodialysis in a different manner. Future investigations are required to address these questions.
Dr. Nigwekar has received speaker honorarium from Sanofi-Aventis and has served as a consultant to Ardelyx. Dr. Thadhani is a consultant to Fresenius Medical Care North America and Celgene, and has received a research grant from Abbott Laboratories.
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Sagar U. Nigwekar, Jeremy M. Weiser, Sahir Kalim, Dihua Xu, Joshua L. Wibecan, Sarah M. Dougherty, Laurence Mercier-Lafond, Kristin M. Corapi, Nwamaka D. Eneanya, Eric H. Holbrook, Dennis Brown, Ravi I. Thadhani, Teodor G. Păunescu. Characterization and Correction of Olfactory Deficits in Kidney Disease. Journal of the American Society of Nephrology, 2017; ASN.2016121308 DOI: 10.1681/ASN.2016121308
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