Positive Options for Living with Lupus (7 page)

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A number of therapeutic drugs are also known to cause lupus or, more correctly, lupus-like symptoms. It’s not true lupus because once the drugs are withdrawn the condition disappears and does not recur (more about drug-induced lupus appears in Chapter 9).

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This has been a long chapter because, given the uncertainty surrounding the disease, it has been necessary to consider many factors in order to explore its possible causes. When the various steps that lead to lupus are eventually understood, a much shorter chapter will be required—though longer chapters may then have to be written on treating, curing, or even preventing lupus!

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Chapter 4

Diagnosing Lupus, Part 1:

In the Doctor’s Office

For patients, the experience of lupus starts with symptoms: how they feel and what they see—rash, aches and pains, hair on the comb, fatigue. The doctor is also first presented with the patient’s symptoms. Some can be seen, others discovered by asking questions (taking a history), and yet others detected through the doctor’s knowledge of how the healthy body works and what signs indicate things are going wrong.

Unless faced with the classic butterfly rash, few general practitioners are likely to diagnose lupus in the office. Even with painstak-ing history-taking and examination (the first two parts of diagnosis), certainty may evade them. The fact that fatigue, depression, or general aches and pains are frequently the first presenting symptoms of many conditions can easily throw the primary-care physician off the trail of lupus. Furthermore, although a battery of laboratory tests have now revolutionized the diagnosis of lupus, a doctor needs to know which tests to order.

Lupus patients often see several doctors before they are correctly diagnosed. In 2002 the American Autoimmune Related Diseases Association reported that the majority of those with serious autoimmune diseases had experienced difficulty obtaining a diagnosis. Many had been told their symptoms were “in their heads” or
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that they were suffering from stress. No fewer than 45 percent had been told they were hypochondriacs! A wise physician may order some of the basic tests as soon as he or she has seen the patient, but will also refer the person to a rheumatologist.

Taking a History

History-taking involves the person detailing her symptoms to the doctor, and the doctor asking questions to gain maximum information. The aim is to narrow down the possible explanations—disease candidates—and then to eliminate them and arrive at a differential diagnosis. Suppose the patient has fatigue, fever, rash, hair loss, or aches and pains; the doctor needs to rule out infection, allergic reaction, or a hormonal imbalance, to name just a few conditions that might cause similar symptoms. Suppose the doctor advances to the conclusion that the patient has some autoimmune condition, or even one of the connective tissue diseases. He or she is still only at first base. How can the field be reduced to one?

To make this task easier, the American College of Rheumatology (ACR) publishes a list of diagnostic criteria for each of the connective tissue disorders. These are basically checklists of symptoms and signs that have been found in international studies to accompany confirmed diagnosis of each condition. They are not a substitute for the individual doctor’s examination of the individual patient, but they do provide guidelines for what should be covered in an examination, and they ensure that the exam is as thorough as possible. ACR’s diagnostic criteria for lupus were first drawn up thirty years ago and have been revised several times. The important physical symptoms are those listed in Chapter 1. Some are more significant than others because they are highly specific to lupus (see the box “Specificity and Sensitivity,” on page 40). Taken together they build a composite picture of the illness.

Symptoms Detected in the Doctor’s Office

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Butterfly (malar) rash
—This is the oft-cited classic symptom, “probably more due to its picturesque name than its prevalence,” says Sheldon Blau. The rash may not be itchy or painful, but may burn slightly on exposure to sunlight. It usually disappears, leaving no mark.

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Discoid lesions
—These are circular, raised, red, scaly plaques. More common in men and in late-onset (older) lupus patients, they were once considered a separate form of the disease because they are often the only lupus symptom patients have. These lesions can leave scarring and permanent hair loss when they heal.

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Photosensitivity of the skin
—This rash specifically follows exposure to sunlight or fluorescent light. Although it occurs in no more than a third of lupus patients it is often a presenting symptom and is highly specific to lupus, particularly if it is accompanied by lupus-type symptoms in other parts of the body.

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Ulcerative sores
—These blister-like sores are sometimes, but not always, painless. They affect the mucous lining of the mouth and throat, and occasionally the vagina. If they’re painless, a dentist may notice them before the patient does.

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Arthritis
—The other classic symptom of lupus, arthritis causes pain during motion, as well as stiffness, tenderness, and swelling of peripheral joints (hands, arms, feet, and legs). It is caused by inflammation. Three-quarters of lupus patients present with it, and 90 percent suffer from it at some time, but although common, this symptom is by no means specific to lupus. Literally hundreds of conditions cause joint pain; it is at the top of the list of symptoms seen by primary-care physicians. At first, lupus-related arthritis is indistinguishable from rheumatoid arthritis. Subsequent laboratory tests separate one cause from another.

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Sensitivity and Specificity

Laboratory tests supplement the physician’s know-how and intuition, but they are still far from perfect. And they are imperfect in two ways that also apply to clinical signs. First, they identify some but not all who have a disease—that is, they sometimes give a false negative result. Second, they give a positive result for some people without the disease—a false positive. If the test picks out, say, ninety-nine out of every hundred people with the disease, it is said to be extremely sensitive. If it only gives one false positive result for every hundred people without the disease, it is said to be extremely specific.

So does it matter? Surely 99 percent accuracy is pretty good?

Think of it like this: You are a guard with an X-ray gun that enables you to see if anyone coming through a checkpoint is carrying a hidden bomb. If the test for a hidden bomb is positive you blow the terrorist to kingdom come. If the X-ray gun sees nothing, the traveler is an innocent tourist whom you let pass with a wave. Now suppose your X-ray gun shows a shadow that looks just like a hidden bomb.

You blow it up and—oops, it was a harmless tourist carrying a video camera! Or suppose your X-ray gun misses a terrorist with a bomb and he gets through undetected. Just as bad.

So it is with false negatives and false positives for disease. It is not too serious with a disease like lupus, but suppose you get a false negative for HIV? That person may go on to spread the life-threatening disease, unaware of being at risk. And if you give someone a false positive for HIV a life will be damaged even though that person may not have the disease. This is why medical scientists rely on the sensitivity and specificity of tests so much, and it is unusual for them to base a diagnosis on just one test. As with clinical signs, wherever possible several different tests are relied upon, and if results are negative the tests may be repeated, just in case they were false.

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Chest/heart problems
—The most common of these is pleurisy: inflammation of the membrane enclosing the lungs. But patients may also develop pericarditis: inflammation of the membrane surrounding the heart. The patient usually complains of chest pain especially when breathing deeply. Like arthritis this is not a symptom in any way specific to lupus, and a physician will first wish to POL text Q6 good.qxp 8/12/2006 7:39 PM Page 41

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exclude acute causes like infection or cancer. Again, laboratory tests help sort one cause from another.

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Kidney disorder
—The kidneys are sometimes known as the “silent” organs in lupus because inflamed kidneys produce no obvious symptoms for patient or doctor. (Pain around the kidneys is more likely to be caused by something completely different, for example a urinary-tract infection or a kidney stone.) The clearest evidence that the kidneys are in trouble is fragments of protein or blood cells leaking into the urine that make it look cloudy. Healthy kidneys filter out protein and blood, leaving the urine clear and ster-ile. Another sign that the kidneys may be inflamed is raised blood pressure. Testing blood pressure and urine is a standard part of a thorough medical examination, so physicians will usually pick up any kidney involvement. About half of all lupus patients may have a degree of kidney involvement at some time; reports vary. Once again, taken alone, kidney problems are not specific to lupus.

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Signs of neurological disorder
—Lupus affects blood vessels all over the body. Inflammation of those in the brain may cause headaches, severe migraines with flashing lights, nausea, or vomiting, or even alarming symptoms like seizures or signs of mental disturbance, for example exaggerated and irrational fears (phobias) or hallucinations.

These brain symptoms have only recently been recognized as indicative of lupus; in the past some lupus sufferers were diagnosed as having schizophrenia. But the accumulation of symptoms in other parts of the body confirms their underlying inflammatory origins.

Diagnosis: Craft or Science?

Diagnosis, doctors are taught, is like Gaul: divided into three parts.

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diseases known to you in the hope of making a match or at the very least a differential diagnosis. “It can’t be this, this, or this; so, by elimination, it must be that.” In practice, doctors hardly ever work like this.

Doctors are fond of joking to each other that they can diagnose their patients “at the office door.” And of course, much of what family doctors see is the same—coughs, colds, stress, general fatigue, and old age—but the saying also prevails because they become practiced in reading their patients’ ills from subtle signs. In the words of one doctor, “The eye of the experienced beholder is worth a laboratory-load of tests.” This diagnosis by intuition or divi-nation conjures up the old idea of doctor as magical medicine man, though in practice it is actually diagnosis by expertise gained through experience. The
Oxford Handbook of Clinical Medicine
(OHCM) calls this practice “diagnosis by recognition,” and it probably applies less to lupus than to other conditions; nevertheless, it is interesting to consider this and the other styles of diagnosis.

Diagnosis by recognition. This is the “office door” diagnosis that comes with years of experience. It impresses both patient and medical student (when a student happens to be present). It is hard to quantify, harder still to teach, and it is not infallible. The OHCM

says 20 percent of such diagnoses are demonstrably wrong. Fortunately, the modern laboratory detects such error.

Diagnosis by reasoning. This is the Sherlock Holmes technique.

The evidence for and against each candidate disease is considered, with the aim of excluding it. Whatever remains after elimination is the diagnosis, however unlikely. This system fails because the list of candidates may not include the actual illness in the first place, or because the reasons for dismissing some candidates are faulty. This is why it belongs, like Holmes, in fiction, says OHCM.

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