A new study, published in the Journal of the American Society of Nephrology, indicates that many patients with chronic kidney disease (CKD) have some degree of smell loss, and that impairments in patients’ ability to smell are linked with worse nutritional status.

To look for potential links between olfaction and nutrition, a team led by Teodor Păunescu, PhD, and Sagar Nigwekar, MD, MMSc, from Massachusetts General Hospital and Harvard Medical School, studied 161 individuals: 36 with CKD, 100 with kidney failure, and 25 with normal kidney function.

In smell tests, the average odor identification score was lower in patients with CKD (75.6%) or kidney failure (66.8%) than in controls (83.6%). Patients with kidney failure exhibited higher odor threshold than the remaining participants exhibited, whereas all groups had similar scores for subjective smell assessment.

“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,” said Păunescu.

The researchers also found that reductions in several markers of nutrition correlated with patients’ impaired sense of smell.

“Our ultimate goal is to have an intervention that can alleviate smell loss, and thus to improve the kidney patients’ nutritional status,” said Nigwekar.

When the team conducted a proof-of-concept 6-week trial of intranasal theophylline, an asthma drug, they found an improvement in the ability to smell in five of seven patients with kidney failure.

Study co-authors include Jeremy Weiser, BA, Sahir Kalim, MD, MMSc, Dihua Xu, PhD, Joshua Wibecan, BS, Sarah M. Dougherty, MPH, Laurence Mercier-Lafond, BS, Kristin Corapi, MD, MMSc, Nwamaka Eneanya, MD, MPH, Eric Holbrook, MD, Dennis Brown, PhD, and Ravi Thadhani, MD, MPH.