II. Definitions
- Ageusia- Loss of Taste Sensation
 
- Hypogeusia- Diminished Taste Sensation
 
- Dysgeusia- Altered Taste Sensation
 
- Phantogeusia- Gustatatory Hallucination (without external taste stimulus)
 
III. Epidemiology
- Taste Dysfunction U.S. Prevalence: 19% in age >40 years (27% in age >80 years)
IV. Pathophysiology
- See Smell Sensation
- See Taste Sensation
- Innervation via parasympathetic fibers- Anterior two thirds of Tongue: Lingual nerve
- Posterior one third of Tongue: Glossopharyngeal Nerve
 
- Loss of Taste Sensation is usually due to Anosmia- Tongue differentiates only bitter, salt, sour, sweet and savory (umami)
 
V. Precautions
- Most altered Taste Sensation is secondary to Olfactory Dysfunction (95% of cases)
VI. History
VII. Causes: Altered or loss of Taste Sensation
- See Olfactory Dysfunction
- Miscellaneous Causes- Aging (difficulty detecting salty or bitter taste)
- Anxiety Disorder
- Cancer
- Renal Failure
- Hepatic failure
- HIV Infection
 
- Endocrine Disorders- Cushing's Syndrome
- Hypothyroidism
- Diabetes Mellitus (poorly controlled)
 
- 
                          Vitamin Deficiency
                          - Vitamin B12 Deficiency
- Vitamin B3 Deficiency
- Zinc Deficiency
- Copper Deficiency
 
- Local injury or inflammation- Radiation Therapy (secondary Xerostomia and mucositis)
- Glossitis
- Tobacco Abuse
- Denture use (if associated with poor hygiene or cleansing of dentures)
- Periodontal Disease or Gingivitis
- Middle ear surgery (affecting Chorda Tympani)
- Dental surgery (wisdom Tooth Extraction is more commonly related)
 
- Local infection- Oral Candidiasis
- Oral abscess
- Upper Respiratory Infection
 
- Medications- See Drug-Induced Gustatory Dysfunction
- Chlorhexidine (Peridex)
 
- Neurologic conditions
- Toxin Exposure- See Olfactory Dysfunction for toxin-related causes
- Pepper gas
- Weed killer (trifluralin)
 
VIII. Evaluation
IX. Resources
- Smell and Taste Association of North America
X. References
- Baloh in Goldman (2000) Cecil Medicine, p. 2249-50
- Mirowski in Feldman (2002) Sleisenger GI, p. 339-40
- Malaty (2013) Am Fam Physician 88(1): 852-9 [PubMed]
- Savard (2023) Am Fam Physician 108(3): 240-8 [PubMed]
