Subject: REPOST: Diagnosis... ? - diagnos.txt [1/1]

From: [email-masked] (larry withers)
Date: 6 Sep 1995 17:58:21 GMT

Extracted from "Nutrition Therapy"
by Stephen J. Gislason MD

Chapter 7   Diagnosis of Food Allergy 
 
The evidence presented in this review suggests  
that there are a variety of expressions of food  
allergy. Three groups of problems have been  
considered. 
 
*	Common recognized syndromes 
*	Specific diseases  
*	Nonspecific illness 
 
Medical diagnosis is a difficult task that  
combines intellectual and intuitive skills. Well- 
defined nosological entities with structural  
changes in tissues are the easiest diagnose.  
Most medical technology addresses these  
needs. The specification of coronary artery  
disease, for example, can be precise and is a  
tribute to the combined effort of physicians,  
technicians, engineers and equipment  
manufacturers to fully reveal a  
pathophysiological process. The precision of  
these well-defined areas of medical concern  
may mislead the unwary into thinking that all  
areas of medicine are equally well-defined or  
can be well-defined with just a little more  
effort. But  most other pathophysiological  
processes remain obscure and are genuinely  
difficult to characterize and understand.  
Common syndromes are diagnosed on clinical  
grounds often with no objective evidence  
whatsoever.  While the history of migraine  
headaches is distinctive and an astute clinician  
will have no difficulty making the diagnosis on  
history, the emergency room physician will have  
trouble deciding whether patient with a migraine  
story is really suffering or simply wants a  
narcotic drug. The diagnosis of depression is   
another subjective syndrome that requires a  
historical understanding more than positive lab  
tests. The irritable bowel syndrome is a  
diagnosis of exclusion. The patient may suffer a  
great deal but tests are negative repeatedly.  
 
Pragmatic, primary medicine is especially  
difficult because of the wide-range of disorders  
that present in all stages of manifestation. The  
primary physician must deal with patients with  
common syndromes, lacking objective  
specification, with early illness that may  
eventually become well-defined, with in- 
between illnesses, mingled with injuries,   
infections,  addictions, and psychosocial  
problems.  A shift from attempted nosological  
diagnosis to pathophysiological understanding  
may be helpful to understand the patient, but is  
often not acceptable to agencies who pay the  
bills. The insistence of a disease category works  
against progress in understanding disease,  
simply because everyone wants to know what  
this is called and not where it came from and  
how to prevent it from happening. A patient with  
80% coronary artery blockage gets the best  
treatment in our system; a single mother with  
type III pattern illness, living on welfare because  
she is too sick to work gets little understanding  
and no technology is applied to solving her  
health problem. 

Shift From Nosological To   
Pathophysiological Understanding of  
Disease.  
The concept of delayed patterns of immune  
response ("food allergy") to food materials  
provides both a theoretic and  practical basis for   
interpreting symptoms of patients with both  
specific diseases and non-specific syndromes.  
The presence of food allergy ( as a  
pathophysiological mechanism) is concealed in  
a variety of  nosological diagnoses such as  
migraine headaches, asthma, eczema, irritable  
bowel syndrome, depression, panic disorder, and  
arthritis.  Patients with these problems tend to  
have two or more manifestations concurrently in  
a matrix of non-specific symptoms. The grand  
theory of hypersensitivity disease attempts to  
explain these illness complexes as expressions  
of reactive immune networks, responding to  
food and airborne antigens. 
 
The pattern of food-related illness, the sequence  
of symptom production, and the distribution of - 
disturbances in the body can be explained if   
complex causation is assumed.  The temporal  
order of sequential immune responses may be  
appreciated by thinking in terms of simultaneous  
immunologic, physiological and biochemical - 
mechanisms, and followed clinically by careful  
recording of each individual's symptom  
production in response to food challenges.    
Without a well-equipped research laboratory it  
will not be possible to actually measure the  
pathophysiological events. The  patient's  
symptom reports and a general understanding of  
pathophysiology will usually suffice to  
construct an adequate theory (diagnosis) and  
prescribe effective intervention. Often a burst of  
symptoms, emerging over hours or days,  can be  
explained by antigenic material from food   
entering the circulation from GIT and triggering  
a variety of alarm and defense procedures. Food  
allergy is diagnosed by physicians who  
understand the multisystem, polysymptomatic  
patterns of illness involved. These patterns are  
revealed by a careful clinical history, and the  
diagnosis made on clinical grounds.  

Proceed With Diet Revision 
A trial of diet revision is safe, practical and  
effective when the clinical pattern suggests the  
diagnosis of food allergy or when the patient  
believes that food is responsible for causing  
symptoms. Knicker's advice is worth  
repeating:   "To diagnose adverse reactions to  
foodstuffs the clinician chiefly need to be  
satisfied that the ingestion of a food predictably  
and repeatedly causes disease. It is not  
necessary to know the precise triggering  
mechanism or which mediators of inflammation  
are activated. Such information is difficult to  
obtain, often requiring considerable laboratory  
investigation beyond the scope of clinical  
practice." 
 
Gerrard suggested:  " The identification or  
confirmation of IgE-mediated allergy is simple,  
for it correlates well with skin prick tests and  
radio-allergosorbent test results. The  
identification of other adverse reactions to  
foods is more difficult and is sometimes  
hampered by preconceived ideas both on the part  
of the patient and the physician... Foods seem to  
play a part in severe chronic disorders which  
have no recognized aetiology.   To establish the  
role of foods in precipitating these disorders we  
need hospital units where patients can be fasted  
and then tested individual with foods, with  
biochemical and immunological studies if  
required.  Investigations such as these are  
inexpensive and, when foods are implicated, the  
treatment, food avoidance, is cheap.  When food  
avoidance prevents headaches, the irritable  
bowel syndrome, arthralgias, and depression, it  
is more effective and less costly than traditional  
treatment, and the observation also throws light  
on the aetiology of the disorder."     
 
The Core Program, described in the next chapter  
of this review is suggested as both a diagnostic  
and treatment procedure. This standardized  
method of diet revision can be conducted at  
home and spare the patient the inconvenience  
and cost of hospitalization or frequent office  
visits. In the era of cost-containment and  
increased patient responsibility for self-care, a  
well constructed diet revision program  
empowers the patient to resolve health problems  
with a minimum of medical interventions. 

Tests For Food Allergy 
This review addresses, briefly, some of the   
testing and treatment issues and confusions  
about food allergy. The difficulty in diagnosing  
food allergy and other food-related problems in  
clinical medicine and disputes within the   
allergy community have left many  patients  
suffering, frustrated and confused. At the same  
time as physicians default in the diagnosis and  
treatment of food-related illnesses, many non- 
medical practitioners have launched careers in  
the food and chemical "sensitivity" business,  
using diverse, sometimes curious and bizarre  
methods,  dubious tests and questionable  
treatments. Even well-intentioned efforts to  
diagnose and treat allergy are often based on  
faulty premises and fail to deliver proper  
results. The desire for simple, definitive tests  
for food allergy is easy to understand, but  
difficult to fulfill. The idea of a simple office  
"test" for food allergy should seem unlikely if  
you understand the complexity and variability of  
immune responses to food antigens. 
 
The lack of specific tests for food allergy have  
hindered progress in this field. Unfortunately,   
tests have been offered which do not reveal the  
problems in a reliable manner. The proliferation  
of phony tests has made responsible work with  
food allergy all the more difficult. Most  
physicians shy away from the  murky issues  
involved. Naturopaths, for example will "muscle  
test" or will use Vega meters - devices which  
only measure skin resistance, but are held out to  
be reliable indicators of "food sensitivity".  Vega  
meters are also used to determine and monitor  
"desensitizing drops" - usually homeopathic  
dilutions of "active substances". This nonsense  
now extends to other devices including  
computers which print out pages of sensitivity  
information and advise food and chemical  
avoidance. Electrodes are attached with some  
mysterious connection or another to the  
computer.  
 
Also unfortunate, has been the insistence of  
some allergists on the skin test as definitive in  
food allergy. The skin test is  a limited  
exploration of immune reactivity and is most  
useful in the investigation of hay fever and other  
inhalant allergy.  The prescription of  
desensitizing sera in hay fever management  
depends on the skin test. IgE RAST tests  
basically show the same reactivity as skin tests  
and are more expensive to do. American labs  
offer other tests for food allergy, including IgG  
RAST, and  immune complex assays. While  
these tests produce interesting results, they are  
expensive and  do not answer the main question -  
what should the patient eat? 
 
The following questions must be asked about  
every proposed test: 
 
What is the test simulating?  Is the simulation  
related to eating real food in real time, by real  
people, exposed to many other influences? Does  
this test do a credible job of simulating  
digestion and absorption? Are the testing  
substances representative of foods, actually  
eaten?  Are the results reproducible? Are the  
test results just spot samples or do they  
represent the sequential interaction of food with  
body systems? Does the test simulate problem  
with GIT permeability and does it demonstrate  
the different responses to varying doses and  
frequency of food ingestion? 
 
The only test that answers all the simulation  
criteria, is to actually eat the food as meals over  
days to weeks and observe what happens. When  
the simple model of linear IgE-mediated  
reactions dominate thinking, some unreasonable  
demands for "proof of food allergy" are placed  
on physicians and patients alike.  The notion that  
double blind food challenge is essential for the  
diagnosis and before diet revision is prescribed  
is among the most impractical, and sometimes  
refractory ideas. Food allergy research should  
include studies of people who are evaluated by  
double-blind challenge with food materials in a  
variety of circumstances. But, very limited  
conclusions can be drawn from these isolated  
experiments. We should never learn to  discredit  
the evidence that patients bring us during  their  
forays in the real-world. 

Allergy Skin Tests 
Skin tests can reveal some of the immediate- 
type hypersensitivities to food materials and are  
always of interest, when distinctly positive. If a  
food extract produces a wheal > 10 mm,  the  
food  probably should not be eaten. However,  
the skin test does an enormous disservice if it is  
used to deny food allergy. A negative skin test  
for food is meaningless. The entire spectrum of  
delayed pattern food allergy lies beyond the  
predictive abilities of this elementary form of  
immunological testing.  

Provocation Tests: by Injection  
Provocation tests by needle injection of food  
proteins into the skin have also been used. The  
intradermal (ID) injection test will occasionally  
show a delayed, cell-mediated response in 24- 
48 hours. Symptoms may develop as injected  
antigen reacts with skin mast cells, or reaches  
circulating basophils and triggers an amplified,  
immediate alarm-response. There is no question  
that injected antigen can sometimes  
demonstrate symptom-production in the allergic  
patient. Indeed every allergist is concerned  
about triggering life-threatening anaphylactic  
reactions with any injection.  If major symptoms  
do occur to one injected antigen, further testing  
is invalid for several days. Clinical ecologists  
claim to "neutralize" the reaction by injecting  
further doses of antigen at  different  
concentrations, and often test many substances  
in one session, lasting several hours. No  
meaningful conclusions can be drawn from  
these testing marathons. The subject tends to  
have fluctuating, confusing sensations, and is  
extremely vulnerable to suggestion from the  
testing person. The ID provocation test is not  
reliable in predicting responses to foods,  
actually eaten, and should not be used as the   
basis for recommending diet revision.  A small  
study by Jewett and associates in California   
questioned the validity of provocation tests; 18  
patients were tested by this method  and they  
concluded that subjects hard a hard time  
differentiating active from inactive solutions,  
and the neutralizing effect was not related to the  
concentration of the active ingredients. This  
study failed to support the method of  
provocative testing - fair enough but an  
associated editorial in this esteemed journal  
used this result to further prejudice against  
food-sensitive patients;  with the byline,  "Food  
Sensitivity or Self-Deception", the editorial  
hints darkly that patients with food allergy are  
dupes. The mention of food allergy invites   
prejudiced opinions from some  members of the  
medical establishment. The only conclusion we  
can reach about provocation tests and this study  
of it is that if subjects are asked to sit in a room  
for several hours after breakfast or lunch,   
receiving a variety of injections, with a variety  
of distractions and suggestions, explicit or  
implicit, coming from testers and other subjects  
everyone will come to the wrong conclusions  
about what is really going on.  The authors of  
this study did not seem to realize that any group  
of subjects sitting in a room will report  
symptoms, if asked. This is not a mysterious  
"placebo" effect ;  but the "noise" of each  
person's body which becomes apparent to  
everyone who sits quietly and does nothing for a  
few hours. They may be reacting to foods they  
ate before they arrived for the tests - even  
yesterday's foods. The practice of meditation  
will reveal shifting awareness of continuous  
body noise - discomforts of all kinds. 

Cytotoxic Tests  
Cytotoxic tests have been offered  for definitive   
"food sensitivity" determination, and have been  
condemned by the American College of  
Allergists as ineffective. Cytotoxic tests,  
recently marketed, expose blood cells to food  
extracts in a chamber, viewed through a  
microscope; cell counts before and after reveal  
cell damage.. Automation can be applied to cell  
counting and evaluation with computer print- 
outs of test results. While the earlier cytotoxic  
tests have little to offer, more sophisticated  
analysis of food antigen and blood-cell  
interactions is always relevant to understanding  
pathogenic mechanisms. A recent  automated  
test has been offered as the ALCAT diagnostic  
system . The ALCAT brochure repeats the  
understanding that multiple mechanisms are  
involved in food allergy and that responses to  
food antigens  by various blood components  
should be measured in food allergic individuals.  
The predictive significance of these  
measurements remains to be discovered. 

Antibody Tests  
The IgE model of allergy inspired development  
of antibody-measuring laboratory tests. The idea  
was to show the affinity of circulating  
antibodies to different antigens. RAST has been  
used instead of, or in addition to, skin scratch  
tests to assess food allergy. Whenever IgE  
mechanisms dominate the food allergy problem,  
RAST may be a useful test. Variations of the  
RAST bear the acronyms ELIZA, FAST, and  
MAST. Negative RAST results have been used to  
deny food allergy and seemed more  
authoritative, looking official and "scientific" on  
a computer printout from the lab. This  RAST- 
test denial only demonstrates ignorance of the  
many mechanisms of food allergy, not related to  
IgE or not involving the small number of test  
antigens, selected from a much larger number of  
possible antigens in the food supply.  
 
The principles of RAST testing for IgE are now  
applied to the measurement of other antibody  
types. The measurement of IgG is of great  
interest. Current studies suggest frequent IgG  
responses to food antigens. Tests measuring  
food-antigen specific IgG have been offered  
with an impressive computer-report of "food  
sensitivities". The levels of food-specific IgG  
are listed, and avoidance of  foods with  
increased antibody levels  is advised. Helpful  
food lists and food rotation instructions  
accompany some of the lab reports. It would  
appear the problem of food allergy diagnosis is  
solved.  Again, this simplistic approach to food  
allergy diagnosis is bound to mislead. While it  
is possible that avoidance of IgG-positive foods  
will be helpful, we do not know if that avoidance   
will really resolve the illness problem. In my  
experience with the IgG RAST, the predictive  
value for food reaction is  limited. 
 
The measurement of total blood levels of four  
antibody species (immunoglobin  
electrophoresis) is of some interest in the  
complex food allergy patterns. Very often,  
shifts in the distribution of IgG, IgM, IgA, and  
IgE manifest immune activity in response to  
antigen loading through GIT. The most common  
pattern is an elevation of the IgM with a very low  
IgE level.  Depressed levels of IgM, IgG are  
seen in patients who have severe or prolonged  
food allergy; often  white cell counts are also  
depressed. When IgE levels are low, skin testing  
and IgE RAST are of little value. Low IgA  
predisposes to food allergy, and always suggests  
the diagnosis. Occasionally, elevations in IgA  
and IgG are seen in the food allergy complex.  
High IgG is associated with the more serious  
immune-mediated diseases, and reflects  
increased antibody production, often against  
unknown antigens. Normal levels of these  
antibodies do not rule out the diagnosis of food  
allergy. 

Immune Complex Assays  
The detection of circulating immune complexes  
is an important test of the antigen-entry  
mechanisms. Usually this procedure is reserved  
for research, and is not routinely employed in  
patient evaluation. Improvement in techniques  
and automation is currently making CIC  
measurement more practical. The most  
interesting test procedures not only detect  
CIC's, but also determine what food antigens  
have complexed with antibody.  This  
demonstration of    food-antigen-containing  
CIC's is gratifying, since the phenomenon of   
antigen-entry is demonstrated. Unfortunately,   
the uncertainty principle recurs when we attempt  
to interpret the test results in terms of  
dysfunction and disease. Immune complexes  
differ in their size, shape, and biological  
significance; some may be very dangerous,  
others benign. Their dysfunctional results will  
surely depend on the kind, amount, and  
frequency of CIC formation. The amount of  
antigen appearing in the blood, compared with  
the amount of antibody available, determines the  
expression of the immunological response.  
Some CIC's excite reactions, other CIC's  
increase suppressor effects, others probably do  
both. The complexities of the immune-network  
challenge the understanding of even the most  
knowledgeable experts. Antigens which escape  
complexing with circulating antibody may be  
another sort of problem. More research is  
needed before immune complex assays will be  
reliable, predicting reactions to foods actually  
eaten.  
 
The conclusions regarding immunological tests  
for food allergy can be summarized; no single  
antibody measurement will predict the immune  
response to food; and no single type of lab  
measurement should be used as the only  
diagnostic test for food allergy. One reason for  
not pursuing immunological tests as a basis for  
practical problem-solving in the Doctor's office  
is that they will be too expensive.  
 
Permability Measurements 
In Vitro Cell Behavior 
 Knicker Wm. Non-IgE mediated and delayed 
adverse  
reactions to food or additives. 1985 Handbook On  
Food Allergies. J.C. Breneman  ed. Marcel Dekker  
Inc. N.Y. 
 Gerrard, J. W.  Letters to the Editor: Food 
Intolerance.   
The Lancet. Aug 18, 1984. Vol. II.  pp 413. 
 Jewett D.L., Fein G., Greenberg M.H. A Double-
Blind  
Study of Symptom Provocation To Determine Food  
Sensitivity. NEJM;323,7:429-433 1990. 
 ALCAT Diagnostic  Systems. 19100 W. Dixie Hwy,  
Miami, Fl 33180. 
 Learey HL, Halsey JF. An assay to measure antigen- 
specific immune complexes in food-allergy patients.  
Jour Allergy Clin Immun 1984;74:(2)190-195.