Tests for taste and smell disorders

Occasionally an ear, nose, and throat (ENT) specialist will suggest a biopsy to look at a tiny sample of your olfactory epithelium (the area at the top of your nose containing smell receptors). Otherwise, smell and taste disorder diagnoses rely on a series of specialized tests.

Specialized tests are particularly useful for diagnosing taste and smell disorders because, unlike hearing or sight problems, most people have great difficulty assessing their senses of taste and smell and there is almost no correlation between how people describe their sense of smell and their actual performance in tests.

• One study of elderly people reported that 77 per cent of those with serious loss of smell described their sensation as "normal."
• In another study, 13 older people who claimed to have a normal sense of smell were found in tests to have none.
• That's not something that generally happens with, say, blindness.  Your doctor may initially use a basic smell test where you see how close to your nose a distinctive-smelling substance has to be before you detect it.
• Or he or she may test each nostril separately with a series of bottles containing common, readily-recognized smells such as lemon or coffee.

Smell:

• To check your ability to distinguish between different odours you may be asked to take a "scratch and sniff" test, sometimes called an UPSIT (because its formal name is the University of Pennsylvania Smell Identification Test).
• This simple test takes about 10 or 15 minutes to complete, and can be done at a clinic or at home. It involves booklets containing a series of 40 scratch panels embedded with specific odours at the bottom right-hand corner of each page.
• You simply scratch each panel with the tip of a pencil, then choose which smell it is most like, from four options given on the page, for example, does it smell most like (a) gas (b) pizza (c) peanuts (d) rose.
• Your answers are then compared with standard responses given by people of the same gender and age band.
• This is the test that has been most commonly used for smell disorders.  A more recent variant on the "scratch and sniff" test are "Sniffin' Sticks." These look like ordinary felt-tip pens, but they are filled with fluids containing different odours.
• Sometimes the odours are presented on little discs — but the principle is the same. Your doctor may use one of two fairly simple taste tests to rule out taste disorders, which are rare if you're not also suffering from loss of smell.Taste:
• The first is known as a "taste and spit" test (or sometimes "sip, spit and rinse"). As it suggests, you are asked to sample a series of liquids and identify basic tastes such as salty, sweet, sour and bitter.
• Or you may be given taste strips, small pieces of filter paper soaked with specific flavours that are placed on the tongue. These also enable testing of different areas on the tongue.