Disorders of taste and smell can cause an aversion to food in a sick patient and therefore affect his/her ability to maintain optimal nutrition. This can lead to a reduced level of strength, muscle mass, function, and quality of life. Additionally, reduced ability to differentiate between various intensities or concentrations of a tastant can result in increased intake of salt and sugar and exacerbation of chronic diseases such as heart failure and diabetes. These implications can be heightened in the elderly, who are particularly frail and are challenged by polypharmacy and multiple comorbid conditions. In this article, we will review the prevalence, etiology, and management of taste disorders. Additionally, we will review the association between taste and smell disorders and how disorders of smell can affect perception of taste.
Clinical Scenario
Ms. Edwards is an 89-year-old female nursing home resident admitted to an inpatient medicine service for failure to thrive, severe malnutrition, loss of appetite, and a 25-pound weight loss in the past 6 months. Past medical history is significant for osteoporosis, congestive heart failure, chronic renal insufficiency, and hypothyroidism. She has been hospitalized twice during the past 6 months for exacerbation of heart failure, with resultant adjustment of her heart failure medication regimen. She notes a persistent loss of appetite and lack of taste in her food for the past 6 months, preventing her from enjoying her food. She denies any difficulty swallowing, nausea, vomiting, or abdominal pain on eating. She also denies being depressed. Basic blood work indicated acute renal insufficiency due to dehydration, which was corrected with intravenous fluids. Other blood work including electrolytes, liver function, and thyroid function labs were unremarkable. She underwent an upper gastrointestinal endoscopy and a colonoscopy, which failed to show any ulcers or evidence of malignancy.
Terminology and Definitions
Taste disorders (dysgeusias) can be classified into qualitative and quantitative disorders. The qualitative disorders include parageusia (inadequate or wrong taste perception elicited by a stimulus) and phantogeusia (presence of a persistent, unpleasant taste in the absence of any stimulus). The quantitative disorders include ageusia (a complete loss of the ability to taste), hypogeusia (a partial loss of the ability to taste), and hypergeusia (enhanced gustatory sensitivity). Burning mouth syndrome (BMS), also referred to as glossodynia or stomatodynia, is a sensation of spontaneous, continuous burning pain felt in the tongue or oral mucosa, commonly seen in postmenopausal women.
Impairment in sense of smell is called dysosmia and complete loss of sense of smell is called anosmia.
Prevalence
The National Health and Nutrition Examination Survey (NHANES) 2011-2012 reported that more than 5% of the over 142 million US respondents experienced taste disorders, and more than 10% experienced smell disorder in the past 12 months. Sex was not associated with the prevalence of either disorder, but increasing age was associated with increasing prevalence of both taste and smell disorders. Additionally, taste disorders are more prevalent in hospitalized and institutionalized older adults compared with those living in the community. Glazar et al reported taste disturbance in 13.9% of institutionalized individuals, compared with 3.2% of community-dwelling individuals. Aging can affect gustatory function, as observed by increasing of electrogustometry thresholds and reduction in density of fungiform papillae. Numerous medication conditions and surgeries (summarized in Table 1 and elaborated below in the article) are also associated with dysgeusia.
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-Quratulain Syed, MD, Kevin T. Hendler, DDS, Kenneth Koncilja, MD
This article originally appeared in the July 2016 issue of The American Journal of Medicine.
