How Allergy Is Diagnosed

How Allergy Is Diagnosed

EVERYONE IS familiar with the fact that some persons develop rashes if they eat strawberries. This is not due to anything ordinarily poisonous in the strawberry itself, but to a peculiarity in the body cells of the person who eats strawberries. Certain cells are so changed that the strawberries act like a poison when in contact with them. Such cells are known technically as sensitized; the person is said to be in the sensitized or allergic state, and is called an allergic or hypersensitive individual. It should be understood that such individuals may be quite normal and robust in every other particular. Furthermore, it should be understood that the condition is a specific one. In the instance mentioned, it is only the strawberry which causes the rash.

If, for example, a hypodermic injection of egg white is administered to a guinea pig, no harm is done to the animal and it remains perfectly healthy. But if, two weeks later, a second injection is given, the animal dies. During those 14 days, the guinea pig had apparently developed a sensitivity to egg white. Post-mortem examination reveals that death was caused by an overdistention of the lungs, with entrapment of the air in the alveoli, due, in part, to spasmodic contractions of certain muscles, and, in part, to an outpouring of mucus. The guinea pig is said to have died from anaphylactic shock.

The similarity between the symptoms shown by the guinea pig prior to death from anaphylactic shock and symptoms exhibited by persons suffering from asthma was first pointed out in 1910. It is now generally agreed that asthma, hay fever and a number of other human allergic diseases somewhat resemble anaphylactic phenomena in animals.

How Symptoms Are Produced

One of the most striking facts about the history of allergic patients is the occurrence of allergic symptoms in other members of the family. Most observers report such a history in over one-half of the cases. Some believe that the tendency to allergy is inherited. This, however, has never been definitely established. Possibly, the ease with which a patient can acquire sensitiveness may be an inherited quality.

In our own series, 50 per cent of the patients had a family history of allergy. The actual proportion, however, may have been higher, because most persons recall only cases of hay fever and asthma, usually forgetting or failing to report eczema, hives or other allergic conditions in the medical history of the family. In view of these findings, we believe that most patients with allergic symptoms have a natural tendency to allergy—the sensitive state that comes about when the patient’s body develops the ability to react. A person may be in the allergic state for many years before symptoms are manifested. Not until that patient comes in contact with an adequate dose of the specific substance to which he is sensitive do symptoms occur. Just as in the guinea pig, the shock is produced only by the particular substance to which he is sensitive. The severity of the symptoms depends upon the size of the dose, the degree of absorption and the sensitivity of the patient. The particular symptoms depend upon the organs or tissues of the body which are sensitive. If the skin is the sensitive tissue, eczema or some other skin disease will be produced; if the lung, asthma, spasmodic croup or spasmodic bronchitis; if the nasal mucous membrane, hay fever; if some portion of the alimentary tract is the sensitive tissue, digestive disturbances will result.

Many individuals possess a threshold of tolerance for the specific substance to which they are sensitive. They will not show any reaction to a small dose, developing under those circumstances what Vaughan called the “balanced allergic state.” Any small additional dose may then bring on symptoms. There are also certain patients in a balanced allergic state who will develop symptoms from additional irritations of a general character.

Specific substances which can produce allergy are technically called allergens. They may enter the body in four ways: through the mouth or nose during breathing, through the digestive tract, through the skin by injection or absorption and (in the case of bacteria) by infection. Under modern conditions of life, we come into daily contact with countless substances, many of which are allergens. The air we breath always contains floating particles of many kinds, such as pollen, dust from leaves, particles from the dandruff and hair of animals, dusts produced in industrial processes and so forth. Any of these may affect an allergic patient through the mouth, nose or skin. Any food may be an allergen for a particular patient. The most common foods are the most frequent offenders in this respect. Bacteria may act as allergens.

In addition, there are many stimuli which produce symptoms when the patient is in the balanced allergic state. However, these influences bring on symptoms only when the patient has had a dose of the specific allergen which affects him. Among these irritations, are weather changes, exposure to heat or cold and certain nervous influences.

How Diagnosis is Made

The diagnosis of any disease may be divided into two parts, the history and the examination. History is of extreme diagnostic importance in allergic patients. The age of the patient, the age at which symptoms began and the frequency and severity of attacks must all be ascertained. The home environment, the presence of animal stables or special factories in the neighborhood, the type of bedding and furniture used, all are significant. The history of attacks following some specific exposure and the existence of an allergic family history are of great importance. A carefully obtained history will usually enable the physician to be certain of the existence in the patient of an allergic state, and may afford some clues to the exciting causes.

The basis of all examinations is the investigation of every organ of the body by a physical examination, supplemented by studies of the blood and urine. This will disclose any intrinsic causes for the symptoms, such as nasal sinus disease, abscessed teeth, diseased tonsils, infections elsewhere in the body or chronic heart or lung disease, and may disclose other changes in the blood suggestive of allergy. Finally, special examinations are available to furnish clues as to the nature of the specific allergens.

The basis of the examination is the cutaneous or “skin” test. Years ago, it was observed that, if pollen was rubbed into the scarified skin of a hay-fever sufferer, an urticarial wheal or hive would develop at the site of the scratch, and that this reaction could be produced only by the particular pollen to which the sufferer was sensitive. Later, it was determined that other substances to which the patients were sensitive would give similar reactions, and this method is now in general use for the purpose of affording clues to the specific allergens in any case. When these clues have been obtained, we plan experiments in which contact with the suspected allergen is avoided. If the symptoms are brought under control, it is then necessary to expose the patient to the specific allergen to see if the symptoms can be reproduced. This must be done with each allergen which gives a positive skin test before it can be included in or excluded from the list of specific causes. It is in this part of the study that the cooperation of the patient is so vital, as the avoidance of specific allergens can be accomplished only with his help.

Other Allergic Conditions

In addition to hay fever and asthma, certain other manifestations of allergy are produced when organs other than those of the respiratory tract are the sites of the shock reaction.

The most common of the nonrespiratory allergies are eczema and urticaria. Some cases of mucous colitis, many of the so-called “gastrointestinal upsets” of children and certain joint affections are allergic in nature. Although these conditions may exist alone, they are usually associated with some other form of allergy. Many asthmatics—20 to 40 per cent according to different observers—give histories of eczema during infancy or childhood, and frequently hay-fever sufferers report attacks of hives at various seasons of the year. Many infants with eczema are troubled by “gastrointestinal upsets,” occasionally complicated by convulsions of an allergic nature.

Foods are usually the responsible factors, but other allergens are sometimes to blame. As in other forms of allergy, the history and the skin reactions provide clues which are to be followed, as described in detail in the preceding pages. If this fails to produce complete relief, the patient should be placed on a diet containing no more than two or three foods, preferably those seldom eaten, for a period of from seven to 10 days. If the symptoms disappear, one new food is added I every week, as long as no symptoms recur, until a pleasant and adequate diet has been established.

Complete study of all infants and children with allergy is imperative, as, by this means, allergens which may cause symptoms later in life may be discovered and eliminated to prevent the precipitation of attacks in adolescence or adult life.

Cooperation Between Patient and Physician

The most common impediment to success in the treatment of allergic conditions is the attitude of the patient. This attitude is one of skepticism, indifference and unwillingness to cooperate fully for an extended time. We know of few illnesses in which patients, as a class, are so difficult to manage. Sufferers from tuberculosis, heart disease, diabetes or even cancer will usually go to any length to cooperate with the doctor if the essentials of treatment are explained to them. This is not often true, however, of patients with chronic allergic symptoms. This is not a specific result of the disease, allergy, but is due rather to the fact that the sickness is a prolonged one, rarely terminating fatally, that it is subject to frequent changes for better or for worse without apparent cause and that a bewildering array of drugs and “cures” is being constantly and persistently pressed upon the patient.

Few disorders can become as chronic as allergy. It can be present from infancy through old age. Few diseases are subject to such rapid and apparently unexplainable change. Finally, few disorders expose the public to greater exploitation.

Many patients are willing to try any number of “treatments,” usually remedies recommended to them highly by their friends or neighbors as positive cures. They experience so many disappointments that they eventually become unwilling to make any serious effort which requires time, sacrifice or conscientious obedience to orders. This is unfortunate for few diseases require more care, study and time, both for diagnosis and treatment, than do allergic conditions.

Unhappily, this attitude of hopelessness is not limited to patients. Many physicians also seem to despair of effective treatment in allergic conditions. By experience, these chronic conditions often resist treatment, only to improve spontaneously without apparent cause. The physician rightfully questions the effect of any specific therapy for a disease which often gets better without treatment. Most doctors, furthermore, have tried highly recommended remedies and have had so many disappointments that they are inclined to scoff at enthusiastic statements concerning the possibility of relief. This is unfortunate, for patients are sometimes persuaded to abandon treatment because of a casual remark made by a physician of their acquaintance.

Finally, the physician should familiarize himself with the fundamentals of allergy before undertaking the complete management of a patient; otherwise, disappointment is almost certain. Nothing could be more preposterous than the view, too widely held, that a diagnosis can be made by the use of a few skin tests, or that a cure can be effected by injecting the patient with materials which give a positive reaction. This reasoning may be correct in a very small proportion of pollen-sensitive patients, but it is decidedly incorrect when applied to the greatest number of patients, particularly those with perennial symptoms.

Methods of diagnosis and treatment which have been recommended in good faith, and which have been made as nearly foolproof as possible, are certain to fail in most cases unless they are associated with a thorough study of the individual. In this, more than in any other disease, methods of diagnosis and treatment must be modified to suit the individual patient. The same technique which succeeds in one case may fail to relieve another patient apparently suffering from the same illness. In the appendix, detailed lists of allergens are given to indicate how careful the study must be in discovering the cause of the allergy. Allergies and examples of them are presented which will allow for a greater understanding of the problem involved. Written By: Jack A. Rudolph, M.D. & Burton M. Rudolph. M.D., Continue Reading, Special Tests to Detect Allergens

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