A. Yes. A doctor can use a number of methods to determine your nutritional status. He or she should start with a detailed medical history and a careful physical examination which would include checking your height and. weight; the condition of your skin, hair and fingernails; mucous membranes inside your mouth and eyelids; your tongue and gums, All these body parts can provide clues to your health.
Q. Clues? Such as?
A. A bright red tongue, for instance, might be a sign of a riboflavin or iron deficiency. Skin that feels like coarse sandpaper, a condition called follicular hyperkeratosis, could indicate a vitamin A, E or B complex deficiency. Cracks around the corners of your mouth could mean you're low on riboflavin. And spoon-shaped fingernails could mean your iron levels are hitting rock-bottom.
Q. Must I be severely deficient in a nutrient for signs of deficiency to be so apparent?
A. Probably, Obvious signs do not occur unless the deficiency is fairly severe. However, a good history and a physical examination, if done by someone sensitive to borderline nutritional insufficiencies, might provide clues toward diagnosis. Doctors who suspect nutritional problems rely on observation, along with dietary analysis, medical history and certain tests to make their diagnosis.
Q. What kinds of laboratory tests might a doctor do during a nutritional assessment?
A. This would depend, in part, on what he or she finds during other aspects of the examination. Many different types of tests are available but most of them measure levels of various nutrients in the blood. Some urine tests are also available. It has to be said, however, that the . experts don't always agree on which test best measures a particular nutrient or what the results of a test mean. Also, these tests are not done very often in Bntain. It seems, however, that they are becoming popular in the US.
BLOOD TESTS
Q. What can you tell me about blood tests to assess vitamin or mineral status?
A. tests measure vitamins or minerals in serum (the clear fluid that separates from blood on clotting); in cells found in the blood (such as red or white blood cells); or in whole blood (which includes serum and cells).
Blood tests can be categorized into two basic groups - screening tests and so-called functional tests. Screening tests measure directly the amount of a vitamin or mineral in blood. They can detect severe deficiencies but they often overlook less severe deficiencies which may
Nevertheless cause physical or mental symptoms. Screening tests are often the only with of test that a doctor orders, if he or she orders any nutritional tests at all.
Q. What are functional tests?
A. Functional tests are considered to be more sensitive to borderline mutational deficiencies than screening tests are. These tests assess vitamin or mineral levels indirectly, by measuring enzyme activity or metabolic activity in ceils associated with a vitamin or mineral.
Q. Can you give me some examples of the types of blood tests you are talking about?
A. Iron is a good example because it is frequently and accurately measured. Iron status can be measured in a number of ways, and most doctors believe that using several measures provides a more accurate assessment of iron status than any single measure.
The first (and easiest) tests usually performed are: hemoglobin, which measures the amount of iron in red blood cells, and haematocrit, which simply indicates the ratio of red cells to serum. If these prove to be low, a doctor can then do three more tests to determine the cause’ of a deficiency: a total iron test, which measures all the iron circulating in someone's blood; a serum ferreting test, which measures the body's storage form of iron and can detect if the body has been dipping into its iron stores; and a serum transferring, or total iron binding capacity test, which measures a protein used to trans- port iron from the liver or elsewhere in the body to wherever it's needed.
Q. Are other minerals measured this precisely?
A. No, Many of the standard tests used to measure other minerals frequently are not very sensitive to changes in body status.
Calcium and magnesium are often measured using a serum level, but doctors recognize that the serum level is a poor way to measure calcium or magnesium status, since the body carefully regulates serum levels of both calcium and magnesium, robbing bones of calcium if necessary to maintain adequate blood levels. It is recognized that serum levels of magnesium can be almost normai even when tissue stores of magnesium are so depleted as to cause heart arrhythmias.
Q. Are the tests for vitamins any more sensitive to semen changes in body status than most of the tests for minerals
A. Some are and some aren't. As with minerals, it depends on the test. Functional tests are considered to be more accurate than general screening tests.
Q. It sounds like I can't always rely on a laboratory test to tell me what's going on in my body nutrition-wise.
Is that the case?
A Unfortunately, yes. That's why most doctors rely on a number of diagnostic findings, including laboratory tests,to determine your nutritional status.
URINE TESTS
Q. What about urine tests? What can they tell me about my nutritional status?
A. Urine contains waste matter filtered out of blood by the kidneys. One liter of urine can be thought of as the end result of more than 1,000 liters of blood passing through the kidneys. Urine is most often tested for sugar, or glucose. Glucose in urine probably means diabetes. Protein levels are also measured. The presence of protein usually indicates kidney problems. These tests, however, do not indicate vitamin or mineral status.
Q. What urine tests do measure vitamins and minerals?
A. Less commonly, urine is tested for the byproducts, or metabolites, .of certain vitamins. Abnormalities could mean a problem with the body's metabolism. Abnormal levels of metabolites in the urine may be related to vitamin deficiencies. Urine can also be tested for its levels of minerals, such as calcium or potassium. But these tests are usually done only in research settings.
Other urine tests can be done which give some indication of a person's nutritional status, exposure to toxic metals and metabolism. Many of these tests are, however, less sensitive than Wood tests and so may be used only to corroborate the findings of blood tests.
HAIR ANALYSIS
Q. Can hair analysis tell me anything about my nutritional status?
A. Most nutrition professionals do not consider hair a good indicator of nutritional status. One reason is that hair growth tends to slow down in people who are truly malnourished, increasing mineral concentrations in the hair while the body's stores drop. Hair can also be contaminated by shampoo, dyes or even by the metal of the scissors used to cut it.
Q. So doctors, even those specializing in nutrition, don't order this sort of test?
A. Some continue to use hair analysis and consider it helpful. You should, however, be wary of those who do. Hair can certainly be an indicator of exposure to heavy metals over a period of time - specifically, exposure to arsenic, lead, mercury, cadmium and aluminum. But that is more likely to be appropriate to forensic work than to nutrition.
Q. What would a practitioner do with the results of a hair analysis?
A. Nutrition experts agree on one issue: any hair analysis findings relating to vitamin and mineral deficiencies or toxicities need to be confirmed with other tests (blood tests, for example) before any treatment recommendations can be made.
Q. When would saliva be tested?
A. Saliva testing is not a standard test but it is used by some researchers to check zinc, copper and magnesium status. In checking a person's zinc status, for instance, saliva could be tested for its level of gustin, a zinc-dependent enzyme which influences taste bud growth. Gustin levels drop when someone is deficient in zinc. Gustin levels may also fall if someone has an abnormality of zinc metabolism, a problem that is difficult to measure any other way.
Q. It sounds as if there is a chance my doctor might order a test which doesn't do me much good or, worse, provides misinformation. Is this true?
A. Actually, there is a very good chance that your doctor will do nothing of the kind. If your general health is reasonable and your doctor does suggest nutritional tests, you should ask a few questions: Why are you ordering this test? What do you expect to find? How accurate is this test? What do you plan to do with the results of this test?
What is the potential that I will be misdiagnosed or mistreated as a result of this test? If you are consulting a private doctor you might ask: What do the tests cost? Will I be paying for them myself, or will my health insurance cover it? What happens if I don't have these tests? Will we be missing a potentially essential piece of information regarding my diagnosis? Will it change the course of my treatment Ask for a copy of the test results to read as you review the findings with your doctor. Also ask what the test means in terms of your condition, or in terms of risk factors for disease.
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