Original contributionTaste and smell function in chronic disease:: A review of clinical and biochemical evaluations of taste and smell dysfunction in over 5000 patients at The Taste and Smell Clinic in Washington, DC
Introduction
There are many patients in the United States with taste and smell dysfunction related to chronic disease processes but a systematic, integrated approach to their evaluation has been lacking. To understand these processes an understanding of how these processes occur and how they can be evaluated is necessary prior to application of treatment to correct them.
Taste and smell are chemical senses. Chemosensory activity involving taste and smell function commonly reflects local and systemic changes in bodily function. Many pathologies of bodily function are manifested by these changes in taste and smell function. These changes fall into two classes – loss of sensory acuity and distortions of taste and smell function. These sensory changes usually reflect symptoms of chronic disease processes involving multiple organ systems including endocrine [1], [2], [3], [4], vitamin [5], [6], trace metal [7], [8], metabolic [9], neurological [10], [11], neurodegenerative [12], [13], hematological [14], immunological [15] and other organ systems [16], [17]. These two classes of dysfunction can also reflect local changes in oral or nasal cavities or in the brain although these changes are not the major pathologies which affect chronic taste or smell dysfunction (v.i.). Descriptions of patients with these sensory dysfunctions have been made by many prior investigators [9], [15], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27] related to both local and systemic pathologies but a report of a systematic approach to evaluation of the multiple chronic pathological and biochemical processes responsible for these dysfunctions has been lacking.
In 1971 we published one of the first systematic studies describing one type of chronic human taste and smell dysfunction and its putative anatomical and biochemical pathology [28]. This publication, with its accompanying editorial [29], reported on patients at The Taste and Smell Clinic, established at the National Institutes of Health, Bethesda, MD, in 1970, the first clinical program in the United States devoted specifically to evaluate and treat patients with taste and smell dysfunction. Since that time, with the transfer of The Clinic, first to Georgetown University Medical Center in 1975, and then to the private sector in 1981, we evaluated and treated more than 5000 patients with these sensory abnormalities. During these studies we developed systematic methods to determine clinical characteristics of these patients, systematic techniques to describe, measure and classify their taste and smell dysfunction and systematic methods to determine some of the biochemical factors responsible for the pathology which initiated these chronic sensory abnormalities [30]. Based upon these clinical, sensory and biochemical techniques, treatment protocols were developed which were eventually successful in correcting many of the chronic sensory abnormalities responsible for these dysfunctions.
A tripartite methodology was developed to define these symptoms; this involves a detailed description of the clinical history and pathology with quantitative measurements of taste and smell function, biochemical techniques which define the clinical pathology in blood, erythrocytes, urine, saliva and nasal mucus and integration of these two methods to allow development of effective treatment of these patients.
We will not deal in this study in any systematic manner with treatment protocols to correct these chronic dysfunctions. These protocols have been previously published and are referred to primarily in association with the methodological studies described herein.
Section snippets
History
A comprehensive detailed and specific clinical history technique was developed. In addition to standard, commonly used clinical techniques [31], [32], [33] detailed questions were developed to characterize the complex changes which initiate and perpetuate these sensory dysfunctions.
Clinical history
Over a period of 40 years, 5183 patients were evaluated at The Taste and Smell Clinic in Washington, DC. Results of these studies offer a comprehensive understanding of the clinical pathology responsible for these changes in chronic loss and/or distortion of taste and smell and the biochemical changes responsible for these chronic changes.
Of the 5183 patients studied 2168 (42%) were men, 2997 (58%) were women. Men were aged 1.8–91 years (50.3 ± 0.4 years, Mean ± SEM); women were aged 1.8–96 years (51.2 ±
Discussion
Successful treatment of chronic taste and smell dysfunction depends upon utilization of the tripartite methodology developed in our program over the last 40 years to evaluate these patients. This includes:
- 1)
Clinical evaluations (recognition of clinical symptoms, neurological and physical examinations of the head and neck, quantitative measurements of sensory abnormalities and imaging studies).
- 2)
Biochemical evaluations (determination of pathology found in blood, erythrocytes, urine, saliva and nasal
References (149)
- et al.
Defects of taste and smell in patients with hypothyroidism
Am J Med
(1975) - et al.
Hematopoietic studies in vitamin A deficiency
Am J Clin Nutr
(1978) - et al.
Deficient dietary intake of vitamin E in patients with taste and smell dysfunction: is vitamin E a cofactor in taste bud and olfactory epithelium apoptosis and in stem cell maturation and development?
Nutrition
(2003) - et al.
Decreased taste sensitivity after D-penicillamine reversed by copper administration
Lancet
(1967) - et al.
To smell the immune system: olfaction, autoimmunity and brain involvement
Autoimmun Rev
(2006) - et al.
Hyposmia in acute viral hepatitis
Lancet
(1971) - et al.
Anosmia: loss of smell in the elderly
Otolaryngol Clin North Am
(2009) - et al.
Disorders of smell and taste
Med Clin North Am
(1999) Phantom-limb pain: characteristics, causes and treatment
Lancet
(2002)- et al.
A classification of dysgeusia
J Am Diet Assoc
(1983)