Ageusia (pronounced ay-GOO-see-uh) is the loss of taste functions of the tongue, particularly the inability to detect sweetness, sourness, bitterness, and saltiness. It is typically a symptom of anosmia - a loss of the sense of smell. Because the tongue can only indicate texture and differentiate between sweet, sour, bitter and salty, most of what is perceived as the sense of taste is actually derived from smell. True aguesia is relatively rare compared to the milder forms of taste loss: hypogeusia and dysgeusia. Hypogeusia represents a partial loss of taste whereas dysgeusia denotes a distortion or alteration of taste. The term symptom (from the Greek syn = con/plus and pipto = fall, together meaning co-exist) has two similar meanings in the context of physical and mental health: A symptom may loosely be said to be a physical condition which shows that one has a particular illness or disorder (see... In medicine, a sign is a feature of disease as detected by the doctor during physical examination of a patient. ... The following codes are used with International Statistical Classification of Diseases and Related Health Problems. ... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ... The International Classification of Diseases for Oncology (ICD-O) is a domain specific extension of the International Statistical Classification of Diseases and Related Health Problems for tumor diseases. ... The Mendelian Inheritance in Man project is a database that catalogues all the known diseases with a genetic component, and - when possible - links them to the relevant genes in the human genome. ... The Diseases Database is a free website that provides information about the relationships between medical conditions, symptoms, and medications. ... MedlinePlus (medlineplus. ... eMedicine is an online clinical medical knowledge base that was founded in 1996. ... Taste is one of the most common and fundamental of the senses of animals. ... Many animals have longer and more flexible tongues than humans. ... Anosmia is the lack of olfaction, or a loss of the sense of smell. ... Senses are the physiological methods of perception. ... Look up smell in Wiktionary, the free dictionary. ... Dysgeusia is the distortion or decrease of the sense of taste. ...

Diagnosis

In order to discover the extent of the aguesia, scientists attempt to discern the minimum level of a chemical that a patient can detect by taste. Patients may also be asked to compare various concentrations of chemicals in order that the doctor may ascertain what level of intensity that the patient can differentiate. Various methods are used, including the "sip, spit, and rinse" test as well as direct application of chemicals to the tongue.

Causes

Neurological Damage

Aguesia is typically a function of the loss of the sense of smell, but tissue damage to the nerves that support the tongue can also cause ageusia, especially damage to the Lingual Nerve and the Glossopharyngeal Nerve. The Lingual Nerve passes taste for the front two-thirds of the tongue and the Glossopharyngeal Nerve passes taste for the back third of the tongue. Neroulogical disorders such as Bell's Palsy, Familial Dysautonomia, and Multiple Sclerosis will cause similar problems to nerve damage.The lingual nerve (who is a branch of the facial nerve) can also be damaged during otologic surgery giving place to a feeling of metal taste. Bells palsy (facial palsy) is characterised by facial drooping on the affected half, due to malfunction of the facial nerve (VII cranial nerve), which controls the muscles of the face. ... Familial dysautonomia, or FD, is a disorder of the autonomic nervous system resulting in variable syptoms including insensivity to pain, inability to produce tears, poor growth, and labile blood pressure. ...

Problems with the Endocrine System

Vitamin deficiency, namely vitamins B3 and Zinc, could lead to problems with the Endocrine system, which may in turn lead to taste loss or alteration. Disorders of the Endocrine Sytem such as Cushing's Syndrome, Hypothyroidism and Diabetes Mellitus could lead to similar problems. Ageusia can also be caused by medicinal side-effects from Antirheumatic Drugs such as Penicillamine, Antiproliferative drugs such as Cisplatin, ACE Inhibitors, and other drugs including Azelastine, Clarithromycin and Zopiclone. Niacin, also known as nicotinic acid or vitamin B3, is a water-soluble vitamin whose derivatives such as NADH play essential roles in energy metabolism in the living cell and DNA repair. ... General Name, Symbol, Number zinc, Zn, 30 Chemical series transition metals Group, Period, Block 12, 4, d Appearance bluish pale gray Atomic mass 65. ... Major endocrine glands. ... Hypothyroidism is the disease state caused by insufficient production of thyroid hormone by the thyroid gland. ... For the disease characterised by excretion of large amounts of severely diluted urine, see diabetes insipidus. ... Penicillamine is a pharmaceutical of the chelator class. ... Chemotherapy is the use of chemical substances to treat disease. ... Cisplatin or cis-diamminedichloroplatinum(II) (CDDP) is a platinum-based chemotherapy drug used to treat various types of cancers, including sarcomas, some carcinomas (e. ... ACE inhibitors, or inhibitors of Angiotensin-Converting Enzyme, are a group of pharmaceuticals that are used primarily in treatment of hypertension and congestive heart failure, in most cases as the drugs of first choice. ... Clarithromycin is a macrolide antibiotic used to treat pharyngitis, tonsillitis, acute maxillary sinusitis, acute bacterial exacerbation of chronic bronchitis, pneumonia (especially atypical pneumonias associated with Chlamydia pneumoniae or TWAR), skin and skin structure infections, and, in HIV and AIDS patients to prevent, and to treat, disseminated Mycobacterium avium complex or... Zopiclone (trade names: Imovaneâ„¢ and Zimovaneâ„¢) is a novel hypnotic agent used in the treatment of insomnia. ...

Other Causes

Local damage and inflammation that interferes with the taste buds or local nervous system such as that stemming from radiation therapy, Glossitis, tobacco abuse, and denture use will also cause Aguesia. Other known causes of ageusia include loss of taste-sensitivity from aging (resulting in a difficulty detecting salty or bitter taste), Anxiety Disorder, Cancer, Renal Failure and Hepatic failure. Glossitis is an abnormality of the tongue that results from inflammation. ... Anxiety disorder is a blanket term covering several different forms of abnormal anxiety, fear, phobia and nervous condition, that come on suddenly and prevent pursuing normal daily routines. ... When normal cells are damaged beyond repair, they are eliminated by apoptosis. ... Renal failure is the condition where the kidneys fail to function properly. ... Liver failure is the final stage of liver disease. ...

Sources

• MedTerms Online Medical Dictionary. "Ageusia". Retrieved April 15, 2005.
• Family Practice Notebook. "Taste Sensation". Retrieved April 15, 2005.
• Massachusetts Eye and Ear Infirmary. "Taste Disorders". Retrieved April 15, 2005.