Richard G. Petty, MD

The Dangers of Health Screening

We have talked before about the problems of interpreting blood and other tests. Yet in this land of defensive medicine, most wise physicians have to do an awful lot of screening that is not always in the patient’s best interests.

Here is a recent article from Forbes that looks at seven health screens about which we should, perhaps, think twice:

1. Total body scans
2. PSA screen for prostate cancer
3. CT scan for lung cancer
4. PlacTest to evaluate your chance of a heart attack or stroke
5. Coronary calcium scans
6. CA125 tests for ovarian cancer
7. Vitamin D testing

Controversial stuff, and I can think of a number of other tests about which I have a great many reservations.

The problem is that every advocacy group has a slightly different set of recommendations on screenings. Doctors and patients are getting conflicting and confusing messages about which tests to use.

The second issue is false positives. Even recommended tests yield many false readings. According to research compiled by the United States Agency for Healthcare Research and Quality,  the percentage of false-positive mammograms is between 7% and 8% for women aged 40 to 59 who took the test. The figure drops to around 4% for women 60 to 79, presumably because the chances of getting breast cancer rise as women age. The conclusion is that if every woman between 40 and 59 in the U.S. had a mammogram, a few million would be fretting unnecessarily over a wrong result.

My life’s work has centered on wellness and the prevention of illness, so I would never want to abandon screening. We just need to be very aware of the pros and cons of any tests that we do.

Cognitive Brain Health Test

One of the blogs that never fails to provide me with some food for thought is Zack Lynch's Brain Waves.

He has just alerted his readers to a very interesting resource.

The Brain Resource Company launched a free, confidential, 40-minute cognitive brain test in partnership with the Alliance for Aging Research. The company is offering the test at no cost until May 14, 2007.

When you first click on the link for the test, you are taken to a page on Brain Health with a great many links.

I am extremely familiar with the literature on the brain, aging and cognition. So on your behalf, I passed a critical eye over the material. I was really pleased with it. I have one or two very minor quibbles, and one or two of the links are not working yet, but overall the information is excellent and above all reliable.

One thing about doing the test is that it needs for you to be using Windows. So we Macintosh users are left out in the cold. But the test is well worth doing, so if you are a Macintosh user, you might want to see if you can borrow a Windows machine for an hour.

“Most people would sooner die than think; in fact they do so.”
--Bertrand Russell (Welsh Mathematician, Philosopher, Pacifist and, in 1950, Winner of the Nobel Prize in Literature, 1872-1970)

“The longer I live, the more beautiful life is.”
--Frank Lloyd Wright (American Architect, 1867-1959)

Predicting Response to Medicines

Much as we would all like to rely upon natural and non-invasive approaches to treatment, there are times when pharmaceuticals also have their place.

A common question is whether there are any good ways to predict who will respond to what treatment and whether we can predict the risk of side effects. Unfortunately the answer is that although we are getting better, and the research base if growing rapidly, there is still a lot of trial and error in prescribing.

An exciting and relatively new area is called pharmacogenetics: using our genetic make-up to allow us to tailor treatments to each of us individually. Over the last few months there have been a lot of media reports about being able to use simple blood tests to predict who will respond to antidepressants. (As an example, see this report from the Washington Post).

Unfortunately these reports, though undoubtedly well meaning, have not told the whole story. You might be interested to see a brief article about this interesting topic that helps put things in perspective.

Though there are some highly reputable institutions that are trying to help provide genetic testing not only for drug responses but also to predict the risk of developing certain illness, unfortunately there are also plenty of rogues who prey upon the worried and unwary. I was recently shown pages and pages of all kinds of tests on an individual: genetic tests; biochemical tests; allergy tests and all kinds of unorthodox tests using every imaginable type of gizmo, from magnets to devices claimed to measure the aura.

Not surpringly, the individual was thoroughly confused by this vast morass of information. The best thing to do was to tear it all up and to start again with the simple question: "What do you think is wrong?" Deep down inside, she knew the answer.

I have spent years working in and running laboratories, so I am not shy about using science and technology.

Science and technology must be our servants and not our masters.

“During my eighty-seven years, I have witnessed a whole succession of technological revolutions. But none of them has done away with the need for character in the individual or the ability to think.”
--Bernard Mannes Baruch (American Financier and Government Official, 1870-1965)

“We must learn to balance the material wonders of technology with the spiritual demands of our human race."
--John Naisbitt (American Futurist and Author, 1929-)

“Humanity has passed through a long history of one-sidedness and of a social condition that has always contained the potential of destruction, despite its creative achievements in technology. The great project of our time must be to open the other eye: to see all-sidedly and wholly, to heal and transcend the cleavage between humanity and nature that came with early wisdom.”
--Murray Bookchin (American Ecologist, 1941-)

The Barnum Effect

Whoever would have thought that the quintessential nineteenth century showman Phineas Taylor Barnum, best known for his claim that, “There’s a sucker born every minute,” would one day lend his name to a psychological principle known colloquially as the Barnum Effect or more accurately as the Forer effect.

Barnum was a marketing genius long before Madison Avenue had been built. Born in Bethel, Connecticut in 1810, by 1835 he purchased an 80-year-old slave and displayed her as the 161-year-old former nurse of George Washington. He went on to create “The Greatest Show on Earth,” in which he displayed everything from performing elephants to people with an array of medical maladies displayed for the masses.

The Barnum Effect is a term said to have been coined by the psychologist Paul Meehl, to describe a very real psychological phenomenon in which people tend to accept as accurate a general statement about themselves, especially a flattering one. Even though the statement could describe just about anyone. Add a few numbers, letters or aspects to the statement, and it is accepted even more quickly, because then it appears to be in some way scientific.

The original experiment was done by Bertram Forer in 1948. He gave his students a personality test, and then gave them an analysis supposedly based on the test's results. He invited each of the students to rate the analysis on a scale of 0 (very poor) to 5 (excellent) as it applied to themselves: the average was 4.26. He then revealed that each student had been given the same analysis.

What he wrote for the students is worth duplicating, because you may have seen similar things written about you, and it is very easy to be taken in. This is what Forer said:

• “You have a need for other people to like and admire you, and yet you tend to be critical of yourself. While you have some personality weaknesses you are generally able to compensate for them. You have considerable unused capacity that you have not turned to your advantage. Disciplined and self-controlled on the outside, you tend to be worrisome and insecure on the inside. At times you have serious doubts as to whether you have made the right decision or done the right thing. You prefer a certain amount of change and variety and become dissatisfied when hemmed in by restrictions and limitations. You also pride yourself as an independent thinker; and do not accept others' statements without satisfactory proof. But you have found it unwise to be too frank in revealing yourself to others. At times you are extroverted, affable, and sociable, while at other times you are introverted, wary, and reserved. Some of your aspirations tend to be rather unrealistic.”

I recently saw this in action when I was persuaded by a friend and life coach to pay almost $50 to do an online evaluation, which turned out to be valueless. Though P.T. Barnum would have been proud of it! Let me explain.

Questionnaires and rating scales can be fun and interesting. After all, books and magazines are full of them. But it is essential not to take most of them too seriously. Designing a rating scale is a huge job. We first begin with an aim for the scale, so that we can later test its face validity: the degree to which it has succeeded in meeting that aim.

After we create it we have to test it and see whether different people can agree on the results. The next step is to see if the findings can be generalized to men and women and different ethnic groups. And finally we have to see whether the results actually tell us anything meaningful from which we can adopt a course of action.

When someone tells me that, “I did a Gnobbly-Komonsky rating scale and it made me see my relationship in a completely new way!” the chances are that the rating scale has nothing to do with it. The only things that can make you see something in a new way is you. Unless validated, tests and scales are rarely more than catalysts. It does not matter if the test has been administered to a million people. If it has not gone through all of the steps to see if its okay, it will never be anything more than a piece of fun that may or may not help catalyze change.

So how do you protect yourself against the Barnum Effect?

1. First, be skeptical, second be very skeptical, and third be very very skeptical
2. Whenever you are given a personal interpretation, whether it comes from a psychologist or astrologer, have a look to see how specific are the interpretations?
3. Next see whether any parts of the interpretation would apply to someone else. (You can test this by taking a horoscope in a newspaper, cutting out the twelve interpretations, without the title, “Virgo, “Scorpio” and so on. Then shuffle them and see which apply to you. Pop astrology is very different from a detailed and personalized evaluation by an intuitive who happens to be using astrology.)
4. Ask how the test was created, and in whom it was tested? Not how many people have taken it, but what independent measures have been used to validate it?
5. Don’t take any action on what you are told until you have objective, external validation.
6. Research has shown that people with higher indices of neuroticism are more likely to fall for the Barnum Effect. If you have fallen for it, see if some of the balancing techniques that I describe on the website might help protect you from making the same msitake again.

If you are interested in going into this in a bit more detail, there is quite a nice article on how to read a medical journal article, that looks at some of the better known fallacies.

Finally here are some more Barnum-isms:
“More persons, on the whole, are humbugged by believing in nothing than by believing in too much.”

“Every crowd has a silver lining.”

Searching for the Laws of Life

In the book of Genesis, God’s fifth act of creation was to create life on earth. Of course, modern science has a different myth.

In the beginning, there was a simple soup of inorganic chemicals: water, ammonia and methane. And into this soup came a bolt of lightning that brought into being the amino acids that gradually assembled themselves into peptides and proteins and the nucleotides from which came RNA and DNA. And the DNA learned the art of becoming self-replicating and so began the ascent of life.

I recently reviewed a fine book – The Fifth Miracle, by Paul Davies - on the Amazon website. Paul points out that believing the scientific myth demands an act of faith and credulity as great as believing in the literal truth of the Biblical story. He is one of many scientists who have calculated the seemingly impossible odds of all this happening by chance. This is not some back door into intelligent design, but instead an exploration of some profoundly important ideas in biology that make us realize that there are some gaping holes in our current models.

We know that inorganic processes tend to run down and become disorganized over time: they show entropy. By contrast living processes become progressively more organized, a process that requires massive amounts of information. It is not difficult to calculate that the amount of information required for even the simplest organism far out strips the biochemical processes of an organism. Thus the implication that life requires a new fundamental law of nature that is yet to be discovered.

If this is true, and the mathematics indicate that it is, it would imply that life should exist everywhere, and wherever it is found it would march toward progressive greater and greater complexity, that would eventually lead to sentience.

The most likely candidate for this natural law is information. The book and CD series, Healing, Meaning and Purpose is dedicated to this notion that a fundamental property of the Universe is conscious awareness and that the first content of awareness is information, in its technical sense. And it is this information together with energy that generates the subtle systems that animate biochemical processes.

Long after I wrote that, I came across an important paper by someone whose work I like very much: William Tiller. In the paper he examines homeopathy as a form of “information medicine,” and comes up with some interesting mathematical modeling to support his conjecture, which I feel sure is correct.

There is also some older data that supports this idea of information. A study from Brazil examined highly diluted thyroid gland extract on the rate at which tadpoles developed into frogs. The extract increased the speed of metamorphosis of the tadpoles, despite the fact that the solutions were so dilute that there could not have been any molecules present. This work was in fact a replication of work done in 1995 in Graz, Austria.

There is a much larger literature than most people realize on this idea of information in biological systems, though most has been presented at meetings or written about in textbooks.

But I’d like to leave you with an interesting paper that is easily accessible. It has the title “Paranormal phenomena in the medical literature sufficient smoke to warrant a search for fire.” The author has done us a great service by collecting a large number of cases of phenomena – collected by physicians and other educated people – that cannot be explained within the current biomedical paradigm. He includes some splendid examples, including the well-documented cases of people being able to speak foreign languages of which they have no conscious knowledge. The most parsimonious explanation for the observations? Information transfer between individuals, even if sometimes separated by many miles.

“Disease of the body as we know it, is a result, an end product, a final stage of something much deeper. Disease originates above the physical plane, nearer to the mental. It is entirely the result of a conflict between our spiritual and mortal selves. So long as these two are in harmony, we are in perfect health: but when there is discord there follows what we know as disease.”
--Edward Bach (English Physician and Creator of the Bach Flower Essences, 1886-1936)

Predicting Osteoporosis

Osteoporosis or thinning of the bones, is an extremely common problem that may lead to bone fractures, particularly in older, postmenopausal women. But sadly we are not good at predicting who will get a fracture. Simply measuring bone density is a long way from being a perfect predictor of who will go on to break bones because of osteoporosis.

A new research study from Melbourne, Australia has just come out in the journal Radiology. The researchers have devised a mathematical formula that is quite good at predicting who will get a fracture over a two-year period. The formula calculate's a woman's risk of developing a fracture with 75% accuracy. The fact that it misses 25% may not sound good, but it's actually a big advance.

The researchers examined 231 women with osteoporosis who had suffered bone fractures and 448 women who had not.They discovered that several factors including bone density levels in the spine and hip, weight, and the number of previous fractures were related to the likelihood of sustaining another fracture. By taking all these measurements into account, the team was able to develop a predictive formula. The formula itself is enough to make your head spin, but it will be very easy to use in practice.

We do have a number of effective treatments, including hormone replacement therapy, vitamin D and calcium supplements, and non-hormonal medicines including the bisphosphonates like sodium alendronate (Fosamax®) 10 mg a day or 70 mg once a week, risedronate (Actonel®) 5mg a day or 35mg once a week or and ibandronate (Boniva® once a month)and parathyroid hormone. There are several other medicines in the pipeline, and there have been claims that homeopathy may also help.

The trouble has been knowing which patients to target. Nobody wants to give everyone medicines if we can avoid it. Hence any form of accurate prediction about who might benefit from what, is to be welcomed.

Remember that there is good evidence that several small lifestyle adjustments can reduce your risk of osteoporosis:

1. Exercise
2. A diet rich in calcium, omega-3 fatty acids and green vegetables. Reduce sodium and refined sugar.
3. Supplemental calcium with vitamin D, magnesium and boron
4. Do not smoke
5. Avoid excessive amounts of alcohol

There are seveal medicines and illnesses that can increase the risk of osteoporosis, and a health care provider will know to be particularly careful about monitoring bone mineral density and applying this new formula.

Measuring Insulin Resistance

After doing so much research, lecturing and writing about insulin resistance, I have constant requests for more information on how to measure it in clinical practice. This is not an academic exercise: it is estimated that a person on the road to developing type 2 diabetes may have been insulin resistant for as long as twelve years before the disease is diagnosed.

In high-risk populations, there is a lot of value in regularly checking plasma glucose, but the problem is that once glucose begins to rise, it implies that the pancreas can no longer keep up with the demand for insulin and that we may be passing the point of no return.

These are the most common questions that I get::

1. Should you be having your insulin level measured?
2. Should you have your insulin resistance measured?
3. What’s normal?

First, measuring insulin levels themselves is not of much value: they bounce around a good deal in the course of a day, and many things can alter your circulating insulin levels.

Second, accurate measurement of insulin resistance is an expensive and cumbersome procedure involving intravenous sampling of blood and in some cases also giving intravenous insulin.

Third, there is no such thing as “normal.” Results derived from any kind of test are a “reference range.” This means that they show how a result related to a large group of apparently healthy people. This is an important concept. I often have students say, “What’s normal?” There is no such thing. Blood tests help and guide us but can only be understood in the context of the whole person.

We never treat a laboratory value: we treat people. You may be interested to have a look at an earlier article about this important issue.

But all is not lost: we do have a blood test that can be used to guide us. We don’t have evidence to suggest that we should be using it to screen the whole population for insulin resistance. Instead it is a test to help guide us in high-risk populations. The test is called the Homeostasis Model Assessment for Insulin Resistance (HOMA-IR).

The original paper was published by a group of experts form the university of Oxford in 1985. The drawback of the HOMA-IR is that it is a mathematical model, and it’s only as good as the accuracy of an individual laboratory’s insulin assay.

Since then, the HOMA-IR has been used in epidemiological studies such as the famous Framingham study and there has been a lot of work on trying to correlate the HOMA-IR with other measures of insulin resistance. There are now over one thousand papers that reference it, and we have had a great deal of experience in using it in our studies of insulin resistance in people with mental illness.

Apart from research, we only use the HOMA-IR as a guide in high-risk individuals. A simultaneous fasting glucose and insulin are taken.

Insulin resistance (HOMA IR) =
Fasting insulin (µU/ml) X Fasting glucose (mmol/l) divided by 22.5.

Most studies now suggest that the cut-off for insulin resistance should be 1.7; although some have been slightly more forgiving, and suggested that up to 2.5 may be acceptable. But remember that the HOMA-IR is only giving us an estimate to help with the overall evaluation of a high-risk individual, and we do not treat a laboratory value.

If the value is above 2.5 many experts would suggest intervention if there are also features of the insulin resistance syndrome. The key interventions are diet and exercise, both of which have been proven to reduce insulin resistance. A very interesting approach adopted in two European studies has been to treat high risk people with a medication called metformin, and were able to show that within a year several cardiovascular risk factors improved.

Health Maintenance: Screening and Prevention

“An ounce of prevention is worth a pound of cure.”
--English Proverb

There is so much that we can do to help ourselves head off serious illnesses.

1. Adopting the kind of health lifestyle that I’ve discussed on previous occasions . Most of us already know the key items: including what to avoid. 
2. Next, be alert to signs an symptoms coming from your body: the Personal Evaluation of Wellness (PEW), is an ideal guide that took years to develop. I plan to make a computerized version soon.
3. Be alert to messages coming from your environment. If something dreadful happens in your life, it makes no sense at all to try carrying on as if nothing happened. The universe may be sending you a message, so use your intuition.
4. Finally, ensure that you get regular health screening. Here is a resource that will point you to the current recommendations about what you should be doing and when.

“Keep your own house and its surroundings pure and clean. This hygiene will keep you healthy and benefit your worldly life.”
--Sathya Sai Baba (Indian Spiritual Teacher, c.1926-

What is Your Risk of Developing Breast Cancer?

When I was first practicing in the United States I was stunned when a research coordinator - who was with me as I examined a young woman – complained that it embarrassed her that I asked the patient about breast cancer screening. I had been trained and then practiced for many years in the United Kingdom, where it would have been deemed negligent if I had not asked the question. As I was taught a long time ago, “When you see a patient, man, woman or child, that may be their only contact with a doctor, so take the opportunity to do as much screening and education as you can.” I still take that to be good advice. We have good data that if women did regular breast self-examination and men checked their testicles, that we would each year catch many cancers at the stage when they are still easily treatable.

I was reminded about all this as I read the shocking results of a study that will be coming out in the European Cancer Journal this month.

In a survey of over 10,000 female students from 23 countries, hardly any knew about any of the major risk factors for developing breast cancer. We have obviously done a lousy job a teaching young people about a disease that may in large part be preventable.

This is desperately important. About 30% of illnesses you cannot help: they are the result of genetic mutations, accidents and so on. But 70% of all illnesses are thought to be the result of lifestyle choices.

Breast cancer is a good example. Yes, there are undoubtedly some cases that are largely genetic: genes have been identified in some families that strongly predispose women – and some men – to the disease. But they are uncommon: probably no more than 5-10% of cases. It is likely that the majority of people with the illness do have a genetic predisposition. But the impact of family history is usually small. And remember that biology is not destiny. Lifestyle modification may indeed significantly reduce your risk.

These are the Major Breast Cancer Risk Factors:
1.    Age
2.    Family history (slight risk)
3.    Starting periods at a younger age
4.    Late menopause
5.    Using hormone replacement therapy
6.    Using the contraceptive pill (small)
7.    Alcohol
8.    Obesity

Please do note that this is not the whole list of risk factors. Perhaps the most comprehensive list is here.

Cutting the Risk:
1.    Breastfeed
2.    Having several children, and having them young
3.    Stay in shape
4.    Eat and drink healthily
5.    Don't smoke

The take home message for everyone is this: lifestyle can strongly influence the risk of developing breast cancer. You cannot change everything, but stopping smoking, cutting down on alcohol, reducing weight and taking regular exercise are in the reach of almost everyone.

Technorati tags: Breast cancer Education Risk factors Health screening

Sex, Time and Energy

I was taking a long flight yesterday, which gave me the chance to read through the results of a large survey  done by Men’s Health and Cosmopolitan Magazines. You will see, gentle reader, how widely I spread my net in my ceaseless efforts to bring you important new materials to enrich your life….

The results of this survey of 6,000 men and women seemed at first to make interesting reading. More than half of men and women surveyed saying that they wanted to have sex at least once a day; around half of the women saying that they wanted to have more adventurous sex, and so the list went on. But then I started thinking: “Who are these people?” They certainly don’t sound much like the people that I know, or people with whom I’ve worked professionally.

So I showed the survey to She Who Must Be Obeyed, and she immediately agreed: “How old are they? And how many of them have children?”

Most healthy adults are interested in having intimate relationships, but how many people are too tired and too distracted to do everything that they want to? And how many people are busily multitasking their lives away to the exclusion of everything else? I was recently talking to a married couple who had packed the children off for the evening and had a date night all organized. The restaurant was booked, the theater tickets in hand, and they both fell fast asleep on the couch and missed both.

I’m sorry to disappoint some of my readers, but the world is not quite the way that it is portrayed in some magazines. At least not once you take on responsibilities. The problem with surveys like this is that it can make some people very dissatisfied, for it leads them into the trap of comparison: “If that’s what the survey says, then what’s wrong with me?” The answer is, of course, that there is no such thing as “normal behavior.” What you and your partner like and feel comfortable with is all that really matters, so long as it isn’t infringing on anyone else. Every time another survey like this comes out, every one of my therapist friends sees an increased number of people worried that they aren’t performing up to par.

Sexual mismatches can create a lot of difficulties in relationships, but let me make a suggestion: the most valuable thing to ensure the viability of intimate relationships is not so much to try to learn lots of different techniques, and it is sometimes just not realistic to put aside as much time for each other as you would like. So instead make the time together really count. There is nothing quite as attractive as an intimate occasion marked by complete focus on and awareness of the other person. Feeling the dance of the duality, focusing on all your senses, and, if you can, feeling the subtle systems of the other person. You already know that our experience of the passage of time is highly elastic. Focused awareness of another person can make even five minutes seem like a lot longer, and remember what I have said before, and is an important theme of Healing, Meaning and Purpose: time management is far less important than energy management.

And remember this: you will never be free so long as you are concerned about the opinions of others.

Technorati tags: sex, relationships, time management

Personal Evaluation of Wellness

As a physician, I am trained to know what questions to ask in order to diagnose health problems and understand what course of action needs to be prescribed to alleviate or cure the problem.  I can be a nightmare for my secretary if she makes my schedule tight because I can spend over an hour with a patient on a first visit.  She would argue that it is more like two hours, but I will admit that I take whatever time I need to gather the pertinent information.

I recently wrote an article that allows one to conduct a personal evaluation of his or her own wellness.  Click here to be taken to it.  It is based on my many years of experience and research.  You will notice that the questions cover the 5 main areas (Physical, Psychological, Social, Subtle and Spiritual) that are key to achieving an overall feeling of wellness and good health.

Keep in mind that this is a bit of a shortened version, there are many more questions that can be helpful.  However, this should get you started about thinking of ways to improve your own sense of health, meaning and purpose.

Technorati tags: wellness, health survey,

What's in Your Blood?

I am sure that you have seen all those credit card advertisements with the tag line: "What’s in you wallet?"

I was thinking about this a couple of days ago when I heard about the husband of a friend of ours who had been in a really nasty motor vehicle accident which left him with several broken bones. After a few days he started to develop problems with his breathing and the family noticed that he was bruising and hemorrhaging from his scars. Yet some of his lab values appeared to be "normal." Fortunately, I was able to offer some advice, and his recovery is now back on track.

But the case reminded me that many physicians have not been taught the value of looking at laboratory values as a whole. Too often we see computer-generated sheets that highlight the "abnormal" values. Yet this is not quite right. First, however good the equipment, laboratory values are never totally accurate. There is always an associated measurement error. This is like those political opinion polls where the expert tells us that the error is + 3%. So if candidate A has 47% and candidate B has 50%, you cannot tell who is winning. Maybe candidate A really has 50% and candidate B really has 47%. Let me give you two clinical examples. I have seen a young doctor who wanted to give someone a blood transfusion because their hemoglobin had fallen by one gram, without realizing that the lab error was + 0.5. So when I asked him to repeat the measurement, there had actually been no change. And I have seen countless people get worried because someone’s temperature has gone up by a degree or two, even though this is within the normal measurement error, and is, by itself, quite meaningless.

And that leads me to the second point: an elevated temperature, or a low hemoglobin, is simply a guide; it is one part of the whole gestalt that we use for diagnosing and monitoring illness. It is wrong to treat a lab value.

Third, when we look at lab values, we are interested in the overall pattern, rather than one result here or there. So I might have a sheet of results in front of me without a single highlighted value, and yet be able to discern a pattern that points toward a specific illness. An individual’s blood chemistry can tell an eloquent story: if you know how to read it.

A fourth point is that for many laboratory tests, there is no such thing as "normal." We use what are known as "reference ranges." Blood levels that have been measured on a lot of apparently healthy people, that are lumped together and used as average reference value for that population. Any deviation is regarded as "out of range," but it does not necessarily mean that it is abnormal. If we go and do another reference range in China or Africa, we may get entirely different results. I once dealt with a large number of patients from some islands in the Caribbean who had two apparent problems: many of them has been misdiagnosed with a condition called acromegaly, a condition in which adults begin to produce large amounts of growth hormone. It can be a nasty illness, and it was apparently responsible for the death of Earl Nightingale, one of the early leaders of the personal development movement. The thing was that amongst these islanders, elevated growth hormone levels were normal and caused no ill health. Second, many ran high levels of an enzyme called creatine kinase that is commonly used to diagnose myocardial infarctions or heart attacks. So we could not use the enzyme for diagnosis in these people unless we saw an extra big change. And that’s an important reason for measuring hormones, chemicals and temperatures: not just to get one-off values, but to monitor change. Once again bearing in mind that any measurement will likely have some level of inaccuracy associated with it.

This last point about reference ranges is exceedingly important. I have seen countless people who have been diagnosed with "subclinical" thyroid or adrenal problems because the treating clinician was not familiar with the interpretation of endocrinological investigations. In a later entry, I am going to discuss why many endocrinologists have become a little skeptical about so-called illnesses like "adrenal exhaustion" and "sub-clinical hypothyroidism."

Technorati Tags: laboratory tests,  medical diagnosis, disease