Allergy / Immunology Flashcards
1
Q
Type 1 - Acute Response
- Mast cell degranulation (releasing histamine). ____ is responsible for most of the acute symptoms. Reaction is ____ mediated.
- Occurs within ___ hour after exposure - usually within minutes.
- Ex: Insect stings, most drug and some food allergies, seasonal/environment allergies, some cases of asthma
Type 1 - Late-Phase Response
- Occurs ____ hours after the immediate reaction. Lasts hours to days. Usually has an eosinophilic inflammatory infiltrate.
A
Type 1 - Acute Response
- Mast cell degranulation (releasing histamine). Histamine is responsible for most of the acute symptoms. Reaction is IgE mediated.
- Occurs within 1 hour after exposure - usually within minutes.
- Ex: Insect stings, most drug and some food allergies, seasonal/environment allergies, some cases of asthma
Type 1 - Late-Phase Response
- Occurs 3-12 hours after the immediate reaction. Lasts hours to days. Usually has an eosinophilic inflammatory infiltrate.
2
Q
TYPE 2 - Cytotoxic Hypersensitivity
- Path: ____ antibody binds to a cell receptor or fixed-tissue antigen. These are autoantibodies. Meditated by antibodies other than IgE. The antibodies target body tissue instead of foreign stimuli.
- In general, reactions are chronic.
- Classic examples: ____ disease (IgA in lungs and kidneys), ___, ___ disease, ___ pemphigoid, ___, hemolytic disease of the newborn
A
TYPE 2 - Cytotoxic Hypersensitivity
- Path: IgG or IgM antibody binds to a cell receptor or fixed-tissue antigen. These are autoantibodies. Meditated by antibodies other than IgE. The antibodies target body tissue instead of foreign stimuli.
- In general, reactions are chronic.
- Classic examples: Goodpasture disease (IgA in lungs and kidneys), AIHA, Graves disease, bullous pemphigoid, ITP, hemolytic disease of the newborn
3
Q
TYPE 3: Immune Complex Hypersensitivity
- A hypersensitivity reaction occurs when an antibody (usually IgG) reacts with a target antigen to form ____s, which precipitate and activate complement with small vessel inflammation and necrosis.
- Typically systemic illnesses
- Examples: ___, ___, ___, ___
A
TYPE 3: Immune Complex Hypersensitivity
- A hypersensitivity reaction occurs when an antibody (usually IgG) reacts with a target antigen to form ICs, which precipitate and activate complement with small vessel inflammation and necrosis.
- Typically systemic illnesses
- Examples: Rheumatoid arthritis, SLE, glomerulonephritides, serum sickness
4
Q
TYPE 4: Cell-Mediated Delayed-Type Hypersensitivity
- Path: _____ dependent.
- Reaction peaks in 24-72 hours.
- NOT antibody or complement mediated. It is a _____ response
- Ex: ____, some types of contact dermatitis, delayed-type hypersensitivity component of asthma, ___ dermatitis
A
TYPE 4: Cell-Mediated Delayed-Type Hypersensitivity
- Path: T-cell dependent.
- Reaction peaks in 24-72 hours.
- NOT antibody or complement mediated. It is a DELAYED response
- Ex: Tuberculin sensitivity (PPD test for Tb), some types of contact dermatitis, delayed-type hypersensitivity component of asthma
5
Q
Contrast-mediated reactions
- Are caused by ___ release from basophils and mast cells. The true cause of this hypersensitivity is unknown, but it is known that unlike true type 1 hypersensitivity reactions, ___ is NOT involved.
- RFs: Previous allergic-like/anaphylactoid reaction, atopy, using beta blockers
- There is no evidence that sensitivity to __ or __ predisposes to radiocontrast media reactions.
A
Contrast-mediated reactions
- Are caused by histamine release from basophils and mast cells. The true cause of this hypersensitivity is unknown, but it is known that unlike true type 1 hypersensitivity reactions, IgE is NOT involved.
- RFs: Previous allergic-like/anaphylactoid reaction, atopy, using beta blockers
- There is no evidence that sensitivity to seafood or iodine predisposes to radiocontrast media reactions.
6
Q
ANAPHYLAXIS
- Path: Type 1 IgE mediated allergic reaction
- Note that ASA-induced anaphylaxis is a separate syndrome from ASA-induced urticaria; both of these are separate from ASA-induced asthma, which is often associated with rhinosinusitis and polyps (Samter triad)
- Pt:
- Symptoms develop within 1 hour of exposure. Usually begins within 5-10 mins after antigen exposure but can be delayed up to 2 hours.
- Involves TWO organ systems
- Urticaria (rash), pruritus, angioedema, flushing
- Urticaria and angioedema are the most common manifestations of anaphylaxis, followed by flushing and respiratory tract symptoms in approx 50% of those affected.
- Cough, wheezing, stridor, dyspnea
- GI: nausea, emesis, diarrhea
- Hypotension is a late finding
- Urticaria (rash), pruritus, angioedema, flushing
A
ANAPHYLAXIS
- Path: Type 1 IgE mediated allergic reaction
- Note that ASA-induced anaphylaxis is a separate syndrome from ASA-induced urticaria; both of these are separate from ASA-induced asthma, which is often associated with rhinosinusitis and polyps (Samter triad)
- Pt:
- Symptoms develop within 1 hour of exposure. Usually begins within 5-10 mins after antigen exposure but can be delayed up to 2 hours.
- Involves TWO organ systems
- Urticaria (rash), pruritus, angioedema, flushing
- Urticaria and angioedema are the most common manifestations of anaphylaxis, followed by flushing and respiratory tract symptoms in approx 50% of those affected.
- Cough, wheezing, stridor, dyspnea
- GI: nausea, emesis, diarrhea
- Hypotension is a late finding
- Urticaria (rash), pruritus, angioedema, flushing
7
Q
- Dx: Clinical, meet any 1 of 3 diagnostic criteria by the World Allergy Organization
- Acute onset (within mins-several hours) of signs/symptoms involving the skin, mucosal tissue, or both (eg generalized urticaria, itching or flushing of skin, swollen lips/tongue/uvula) AND at least 1 of the following
- Respiratory compromise (eg dyspnea, wheeze/bronchospasm, stridor, hypoxia)
- Decreased BP or associated symptoms of end-organ dysfunction (eg fainting, dizziness, incontinence)
- Acute onset (within mins-several hours) of signs/symptoms involving the skin, mucosal tissue, or both (eg generalized urticaria, itching or flushing of skin, swollen lips/tongue/uvula) AND at least 1 of the following
- > 2 of the following occurring acutely after exposure to a likely allergen
- Involvement of the skin and/or mucosal tissue- 80-90% of anaphylactic reactions have some cutaneous manifestations (commonly urticaria and/or angioedema)
- Respiratory compromise
- Decreased BP or associated symptoms of end-organ dysfunction
- Persistent GI symptoms (eg crampy abdominal pain, nausea, vomiting, diarrhea)
- 80-90% of anaphylactic reactions have some cutaneous manifestations (commonly urticaria and/or angioedema)
- > 2 of the following occurring acutely after exposure to a likely allergen
- Decreased BP following exposure to a known allergen (low age-specific SBP OR a decrease in SBP by 30% or more in infants/children)
A
- Dx: Clinical, meet any 1 of 3 diagnostic criteria by the World Allergy Organization
- Acute onset (within mins-several hours) of signs/symptoms involving the skin, mucosal tissue, or both (eg generalized urticaria, itching or flushing of skin, swollen lips/tongue/uvula) AND at least 1 of the following
- Respiratory compromise (eg dyspnea, wheeze/bronchospasm, stridor, hypoxia)
- Decreased BP or associated symptoms of end-organ dysfunction (eg fainting, dizziness, incontinence)
- Acute onset (within mins-several hours) of signs/symptoms involving the skin, mucosal tissue, or both (eg generalized urticaria, itching or flushing of skin, swollen lips/tongue/uvula) AND at least 1 of the following
- > 2 of the following occurring acutely after exposure to a likely allergen
- Involvement of the skin and/or mucosal tissue- 80-90% of anaphylactic reactions have some cutaneous manifestations (commonly urticaria and/or angioedema)
- Respiratory compromise
- Decreased BP or associated symptoms of end-organ dysfunction
- Persistent GI symptoms (eg crampy abdominal pain, nausea, vomiting, diarrhea)
- 80-90% of anaphylactic reactions have some cutaneous manifestations (commonly urticaria and/or angioedema)
- > 2 of the following occurring acutely after exposure to a likely allergen
- Decreased BP following exposure to a known allergen (low age-specific SBP OR a decrease in SBP by 30% or more in infants/children)
8
Q
- Tx:
- *IM Epinephrine 0.__mg/kg (max 0.5mg) 1:___ for immediate response.
- Epipen: for less than ___kg, pediatric version ____mg (Epipen Jr). For >___kg, use adult version ___mg.
- The effects of epinephrine are blunted in pts on beta-blockers, so they are relatively contraindicated in pts at risk of anaphylactic reaction. Suspect beta-blockade if response to epinephrine is poor.
- Pts with evidence of hypotension or shock are immediately given a bolus of normal saline IV. In addition, given epinephrine 0.01mg/kg (max 0.5mg) IM every 15-20 mins as needed.
- Oral benadryl
- H1/H2 blockers, usually diphenhydramine and cimetidine, for response in 30-40 mins. Help relieve hives but not the airway swelling or shock.
- *IM Epinephrine 0.__mg/kg (max 0.5mg) 1:___ for immediate response.
- Prevention (3 As)
- Avoidance of the allergen
- Antihistamines (occasionally steroids)
- Patients with hx of anaphylactoid reactions to contrast should receive ___ AND ___ prior to the next administration of IV contrast.
- Allergen-specific immunotherapy. Takes up to 1 year to show an effect, with maximal effect in 3 years
A
- Tx:
- *IM Epinephrine 0.01mg/kg (max 0.5mg) 1:1000 for immediate response.
- Epipen: for <30kg, use pediatric version 0.15mg (Epipen Jr). For >30kg, use adult version 0.3mg.
- The effects of epinephrine are blunted in pts on beta-blockers, so they are relatively contraindicated in pts at risk of anaphylactic reaction. Suspect beta-blockade if response to epinephrine is poor.
- Pts with evidence of hypotension or shock are immediately given a bolus of normal saline IV. In addition, given epinephrine 0.01mg/kg (max 0.5mg) IM every 15-20 mins as needed.
- Oral benadryl
- H1/H2 blockers, usually diphenhydramine and cimetidine, for response in 30-40 mins. Help relieve hives but not the airway swelling or shock.
- *IM Epinephrine 0.01mg/kg (max 0.5mg) 1:1000 for immediate response.
- Prevention (3 As)
- Avoidance of the allergen
- Antihistamines (occasionally steroids)
- Patients with hx of anaphylactoid reactions to contrast should receive diphenhydramine AND corticosteroids prior to the next administration of IV contrast.
- Allergen-specific immunotherapy. Takes up to 1 year to show an effect, with maximal effect in 3 years
9
Q
ANGIOEDEMA
- Pt: Subcutaneous swelling, particularly of the lips, mouth, face, and throat
- For isolated angioedema without urticaria, consider ACE inhibitor-induced angioedema or hereditary angioedema.
A
ANGIOEDEMA
- Pt: Subcutaneous swelling, particularly of the lips, mouth, face, and throat
- For isolated angioedema without urticaria, consider ACE inhibitor-induced angioedema or hereditary angioedema.
10
Q
URTICARIA
- Pt:
- Wheel, erythema, but no hypotension. TRUE urticaria due to allergy will resolve within 24 hours. Urticaria due to viral infection (most common reason for urticaria in pediatrics) may last longer like a week
A
URTICARIA
- Pt:
- Wheel, erythema, but no hypotension. TRUE urticaria due to allergy will resolve within 24 hours. Urticaria due to viral infection (most common reason for urticaria in pediatrics) may last longer like a week
11
Q
Acute Urticaria
- Superficial, raised, blanching, transient, pruritic skin lesions that have been present for less than ___ weeks, usually lasting for 24-48 hours.
A
Acute Urticaria
- Superficial, raised, blanching, transient, pruritic skin lesions that have been present for <6 weeks, usually lasting for 24-48 hours.
12
Q
Chronic Urticaria
- Urticaria lasting >___ weeks
- Causes:
- Majority (~80%) of chronic urticarial cases in the past were considered idiopathic.
- With the identification of the important role of autoimmunity, ~60% of these previously idiopathic chronic urticaria pts are now considered to have _______ etiologies.
- These pts also have high rates of autoimmune diseases, such as autoimmune hypothyroidism, hyperthyroidism (Graves), SLE, JIA, and RA.
- With the identification of the important role of autoimmunity, ~60% of these previously idiopathic chronic urticaria pts are now considered to have _______ etiologies.
- Physical urticarias (urticaria to cold, heat, pressure, vibration, sunlight, and water (aquagenic)
- Acquired cold urticaria
- Familial cold urticaria
- Cholinergic urticaria
- Immediate pressure urticaria
- Delayed pressure urticaria
- One unique situation of a delayed food reaction that can cause hives 3-6 hours after a meal consisting of mammalian meat. This is when a pt is sensitized to ______ (“alpha-gal”), which is a carbohydrate allergen. Alpha-Gal has been identified as an allergen that is linked to tick bites.
- Dx: ______
- Majority (~80%) of chronic urticarial cases in the past were considered idiopathic.
- Associated disorders:
- Autoimmune disorders: celiac disease, Sjogren, SLE, RA, DM1
- Thyroid disorders: Hypo and hyperthyroidism, check _____!
- Malignancy
- Dx:
- Exclude drugs and systemic signs/diseases.
- Work-up: Do NOT send any routine labs (eg CBC, BMP, ESR, C3, C4, ANA) in the initial workup unless guided by hx and physical. Serum tests for allergen-specific IgE antibodies are appropriate if hx suggests a probable trigger.
- Lab tests are unlikely to reveal abnormalities
A
Chronic Urticaria
- Urticaria lasting >6 weeks
- Causes:
- Majority (~80%) of chronic urticarial cases in the past were considered idiopathic.
- With the identification of the important role of autoimmunity, ~60% of these previously idiopathic chronic urticaria pts are now considered to have autoimmune etiologies.
- These pts also have high rates of autoimmune diseases, such as autoimmune hypothyroidism, hyperthyroidism (Graves), SLE, JIA, and RA.
- With the identification of the important role of autoimmunity, ~60% of these previously idiopathic chronic urticaria pts are now considered to have autoimmune etiologies.
- Physical urticarias (urticaria to cold, heat, pressure, vibration, sunlight, and water (aquagenic)
- Acquired cold urticaria
- Familial cold urticaria
- Cholinergic urticaria
- Immediate pressure urticaria
- Delayed pressure urticaria
- One unique situation of a delayed food reaction that can cause hives 3-6 hours after a meal consisting of mammalian meat. This is when a pt is sensitized to galactose-alpha-1,3-galactose (“alpha-gal”), which is a carbohydrate allergen. Alpha-Gal has been identified as an allergen that is linked to tick bites.
- Dx: IgE to galactose-alpha-1,3-galactose
- Majority (~80%) of chronic urticarial cases in the past were considered idiopathic.
- Associated disorders:
- Autoimmune disorders: celiac disease, Sjogren, SLE, RA, DM1
- Thyroid disorders: Hypo and hyperthyroidism, check TSH!
- Malignancy
- Dx:
- Exclude drugs and systemic signs/diseases.
- Work-up: Do NOT send any routine labs (eg CBC, BMP, ESR, C3, C4, ANA) in the initial workup unless guided by hx and physical. Serum tests for allergen-specific IgE antibodies are appropriate if hx suggests a probable trigger.
- Lab tests are unlikely to reveal abnormalities
13
Q
Chronic Urticaria
- Tx:
- Reassurance
- Most do well with only _______ and avoiding known triggers
- Sedating H1 blockers are the most effective treatment for common transient urticaria
- 1st generation: Benadryl ((1mg/kg, max 25mg), short acting) and hydroxyzine are commonly used
- 2nd generation: Antihistamines that block the H1 receptor and are less sedating compared to diphenhydramine include fexofenadine, loratadine, desloratadine, cetirizine, and levocetirizine.
- Antihistamines that block H2 receptor include cimetidine, ranitidine, and famotidine.
- Sedating H1 blockers are the most effective treatment for common transient urticaria
- Another set of medications that can be used include leukotriene pathway modifiers such as montelukast and zafirlukast.
- A short course of corticosteroids is generally NOT recommended as 1st line therapy.
- Tx:
- Step 1: 2nd generation H1 antihistamines (Cetirizine/Zyrtec, Loratadine/Claritin, Fexofenadine/Allegra)
- Step 2: One or more of the following
- Increasing dose of 2nd generation H1 antihistamine to up to 4x standard dose
- Add 2nd generation antihistamine
- Adding H2 antagonist (famotidine, ranitidine, cimetidine)
- Adding leukotriene-receptor antagonist (Montelukast)
- Adding 1st generation H1 antihistamine at bedtime (diphenhydramine/Benadryl)
- Step 3: Increase dose of 1st generation H1 antihistamine
- Step 4 (Refractory disease):
- Omalizumab (antiE antibody) injections subq every 4 weeks
- Cyclosporine or tacrolimus
- Prognosis
- Self-limited and episodic disease in majority of patients.
A
Chronic Urticaria
- Tx:
- Reassurance
- Most do well with only antihistamines and avoiding known triggers
- Sedating H1 blockers are the most effective treatment for common transient urticaria
- 1st generation: Benadryl ((1mg/kg, max 25mg), short acting) and hydroxyzine are commonly used
- 2nd generation: Antihistamines that block the H1 receptor and are less sedating compared to diphenhydramine include fexofenadine, loratadine, desloratadine, cetirizine, and levocetirizine.
- Antihistamines that block H2 receptor include cimetidine, ranitidine, and famotidine.
- Sedating H1 blockers are the most effective treatment for common transient urticaria
- Another set of medications that can be used include leukotriene pathway modifiers such as montelukast and zafirlukast.
- A short course of corticosteroids is generally NOT recommended as 1st line therapy.
- Tx:
- Step 1: 2nd generation H1 antihistamines (Cetirizine/Zyrtec, Loratadine/Claritin, Fexofenadine/Allegra)
- Step 2: One or more of the following
- Increasing dose of 2nd generation H1 antihistamine to up to 4x standard dose
- Add 2nd generation antihistamine
- Adding H2 antagonist (famotidine, ranitidine, cimetidine)
- Adding leukotriene-receptor antagonist (Montelukast)
- Adding 1st generation H1 antihistamine at bedtime (diphenhydramine/Benadryl)
- Step 3: Increase dose of 1st generation H1 antihistamine
- Step 4 (Refractory disease):
- Omalizumab (antiE antibody) injections subq every 4 weeks
- Cyclosporine or tacrolimus
- Prognosis
- Self-limited and episodic disease in majority of patients.
14
Q
Urticarial Vasculitis
- Pt: Painful, long-lasting wheals 48-72 hours in a fixed location (characteristic) (in contrast to chronic urticaria, which resolves in minutes to hours or migrates continually)
- Can resemble chronic urticaria. However, pts report hives lasting >\_\_h in a \_\_\_\_ location (in contrast to chronic urticaria, which resolves in mins-hours or migrate continually). Other red flags include residual \_\_\_\_\_, hyperpigmentation, or purpura. - Can be associated with an underlying autoimmune disease, most commonly SLE. Therefore, pts should be appropriately evaluated. - Abnormal lab findings include elevated ER, positive ANA, and hypocomplementemia. - Dx: \_\_\_\_\_
A
Urticarial Vasculitis
- Pt: Painful, long-lasting wheals 48-72 hours in a fixed location (characteristic) (in contrast to chronic urticaria, which resolves in minutes to hours or migrates continually)
- Can resemble chronic urticaria. However, pts report hives lasting >24 h in a fixed location (in contrast to chronic urticaria, which resolves in mins-hours or migrate continually). Other red flags include residual ecchymosis, hyperpigmentation, or purpura. - Can be associated with an underlying autoimmune disease, most commonly SLE. Therefore, pts should be appropriately evaluated. - Abnormal lab findings include elevated ER, positive ANA, and hypocomplementemia. - Dx: Skin biopsy
15
Q
ALLERGIC RHINITIS
- RFs: Female gender, a serum total IgE >100 IU/mL before the age of 6, particulate air pollution and maternal smoking.
- Protective factors against the development of rhinitis: Number of siblings at home, use of day care, increased grass pollen counts, living on a farm, Mediterranean diet
- Pt:
- The “_____” occurs with frequent rubbing of the nose and can progress to a transverse nasal crease.
- ____ lines are folds below the eyes due to edema; they frequently accompany allergic shiners.
- The nasal mucosa is usually swollen and pale.
- Pale turbinates is likely due to allergies. Red turbinates is likely due to viral infection.
- “____” of the posterior oropharynx is due to chronic post-nasal discharge.
- Tx:
- Avoidance of triggers.
- Dust mites are a common source of perennial AR.
- Impermeable, zippered covers on mattresses, box springs, and pillows considerably reduce the amount of dust mite allergen in the bedroom by trapping the allergen in its main reservoirs! If coupled with laundering of all bed linens at least every other week, dust mite allergen recovery from bed surfaces is reduced by as much as 90%.
- Effects methods of reducing dust mite exposure: Removing upholstered furniture, heavy draperies, encasing bedding in airtight allergen-impermeable covers, washing bedding weekly in water at temps >130F, removing wall-to-wall carpeting, replacing curtains with blinds, and controlling humidity.
- Dust mites require a relative humidity >50% to be most viable, so suggest measures to reduce in-home humidity. Regular use of humidifiers and evaporative coolers promote dust mite survival, as dust mites do not survive in humidity <50%.
- Dust mites are a common source of perennial AR.
- ______ are 1st line and are the most effective agent for nasal allergies
- Other options are 2nd generation antihistamines (cetirizine, singulair).
- 1st generation histamine blockers (diphenhydramine, chlorpheniramine, and hydroxyzine) have the major side effect of sedation.
- 2nd generation antihistamines (eg cetirizine, fexofenadine, loratadine) do not cross the blood-brain barrier as much and are more specifically aimed at the H1 receptor and not the other receptors.
- Allergen-specific immunotherapy, or desensitization, is generally the last resort in therapy.
- The most common side effect from allergy immunotherapy is the development of a large local reaction, but this is NOT a contraindication to therapy.
- Contraindications:
- Poorly controlled ________ (majority of deaths occur in these patients)
- Pts with poorly controlled asthma should not receive AIT bc AIT can potentially induce a severe asthma exacerbation.
- _______ disease
- _____ and _____. Beta-blockers decrease response to epinephrine that may be needed to combat adverse reactions and ACE-i can accentuate angioedema.
- Malignancy, autoimmune disease, immunodeficiency syndrome (concern that therapy may worsen underlying disease)
- It is NEVER attempted in patients with hx of reactions involving significant skin desquamation, such as________, bc even small doses of the drug may induce irreversible and potentially fatal recurrent desquamative reactions. _____ and diffuse erythroderma with desquamation are other types of reactions for which desensitization should not be attempted. Desensitization is also not indicated for serum sickness reaction, nephritis, hepatitis, and other severe non IgE-mediated reactions.
- Poorly controlled ________ (majority of deaths occur in these patients)
- Avoidance of triggers.
A
ALLERGIC RHINITIS
- RFs: Female gender, a serum total IgE >100 IU/mL before the age of 6, particulate air pollution and maternal smoking.
- Protective factors against the development of rhinitis: Number of siblings at home, use of day care, increased grass pollen counts, living on a farm, Mediterranean diet
- Pt:
- The “nasal salute” occurs with frequent rubbing of the nose and can progress to a transverse nasal crease.
- Dennie-Morgan lines are folds below the eyes due to edema; they frequently accompany allergic shiners.
- The nasal mucosa is usually swollen and pale.
- Pale turbinates is likely due to allergies. Red turbinates is likely due to viral infection.
- “Cobblestoning” of the posterior oropharynx is due to chronic post-nasal discharge.
- Tx:
- Avoidance of triggers.
- Dust mites are a common source of perennial AR.
- Impermeable, zippered covers on mattresses, box springs, and pillows considerably reduce the amount of dust mite allergen in the bedroom by trapping the allergen in its main reservoirs! If coupled with laundering of all bed linens at least every other week, dust mite allergen recovery from bed surfaces is reduced by as much as 90%.
- Effects methods of reducing dust mite exposure: Removing upholstered furniture, heavy draperies, encasing bedding in airtight allergen-impermeable covers, washing bedding weekly in water at temps >130F, removing wall-to-wall carpeting, replacing curtains with blinds, and controlling humidity.
- Dust mites require a relative humidity >50% to be most viable, so suggest measures to reduce in-home humidity. Regular use of humidifiers and evaporative coolers promote dust mite survival, as dust mites do not survive in humidity <50%.
- Dust mites are a common source of perennial AR.
- Intranasal corticosteroids (Flonase) are 1st line and are the most effective agent for nasal allergies
- Other options are 2nd generation antihistamines (cetirizine, singulair).
- 1st generation histamine blockers (diphenhydramine, chlorpheniramine, and hydroxyzine) have the major side effect of sedation.
- 2nd generation antihistamines (eg cetirizine, fexofenadine, loratadine) do not cross the blood-brain barrier as much and are more specifically aimed at the H1 receptor and not the other receptors.
- Allergen-specific immunotherapy, or desensitization, is generally the last resort in therapy.
- The most common side effect from allergy immunotherapy is the development of a large local reaction, but this is NOT a contraindication to therapy.
- Contraindications:
- Poorly controlled asthma (majority of deaths occur in these patients)
- Pts with poorly controlled asthma should not receive AIT bc AIT can potentially induce a severe asthma exacerbation.
- Cardiac disease
- ACE-inhibitors and Beta-blockers. Beta-blockers decrease response to epinephrine that may be needed to combat adverse reactions and ACE-i can accentuate angioedema.
- Malignancy, autoimmune disease, immunodeficiency syndrome (concern that therapy may worsen underlying disease)
- It is NEVER attempted in patients with hx of reactions involving significant skin desquamation, such as Steven-Johnson syndrome or TEN, bc even small doses of the drug may induce irreversible and potentially fatal recurrent desquamative reactions. Erythema multiforme and diffuse erythroderma with desquamation are other types of reactions for which desensitization should not be attempted. Desensitization is also not indicated for serum sickness reaction, nephritis, hepatitis, and other severe non IgE-mediated reactions.
- Poorly controlled asthma (majority of deaths occur in these patients)
- Avoidance of triggers.
16
Q
FOOD ALLERGIES (IGE-MEDIATED)
- Common triggers: WEMPS:
- W___
- E___
- M___
- P___
- S____
- While allergies to milk, egg, wheat, and soy often resolve during childhood (85% of children) (the ones commonly outgrown by 5yo are the only ones with <5 letters), allergies to ___, ___, and ____ are more likely to persist (only 20% of children outgrow).
- Tx:
- Pts with severe food allergy must be prescribed an epinephrine autoinjector and trained in how to use it.
- Avoid triggers and eliminate offending food from child’s diet.
- Allergy-specific Immunotherapy (AIT) approaches that introduce the allergen in small doses to desensitize the immune system to that allergen have emerged in recent years and are offered in specialty settings for select pts.
- In the absence of a recent reaction, many allergists recommend annual retesting for milk, egg, wheat, and soy allergies, and less frequent retesting for allergies more likely to persist.
A
FOOD ALLERGIES (IGE-MEDIATED)
- Common triggers: WEMPS:
- Wheat
- Eggs
- Milk and soy
- Peanuts and treenuts
- Seafood (crustacean shellfish and fish)
- While allergies to milk, egg, wheat, and soy often resolve during childhood (85% of children) (the ones commonly outgrown by 5yo are the only ones with <5 letters), allergies to peanuts, tree nuts, and shellfish are more likely to persist (only 20% of children outgrow).
- Tx:
- Pts with severe food allergy must be prescribed an epinephrine autoinjector and trained in how to use it.
- Avoid triggers and eliminate offending food from child’s diet.
- Allergy-specific Immunotherapy (AIT) approaches that introduce the allergen in small doses to desensitize the immune system to that allergen have emerged in recent years and are offered in specialty settings for select pts.
- In the absence of a recent reaction, many allergists recommend annual retesting for milk, egg, wheat, and soy allergies, and less frequent retesting for allergies more likely to persist.
17
Q
Prevention of food allergies
- Feeding _____ formula during first 4 months of life may help prevent development of both atopic and cow milk protein allergy.
- Delaying introduction of solid foods or highly allergenic foods does not decrease the risk of developing food allergies.
A
Prevention of food allergies
- Feeding hydrolyzed formula during first 4 months of life may help prevent development of both atopic and cow milk protein allergy.
- Delaying introduction of solid foods or highly allergenic foods does not decrease the risk of developing food allergies.
18
Q
Guidelines for prevention of peanut allergies
- Infant criteria
- Severe eczema, egg allergy, or both
- Rec: Strongly consider evaluation by sIgE measurement and/or skin prick test
- Mild-moderate eczema
- Rec: Introduce peanut-containing foods around 6mo
- No eczema or any food allergy
- Rec: Introduce peanut-containing foods at appropriate age in accordance with family preferences and culture practice
- Severe eczema, egg allergy, or both
A
Guidelines for prevention of peanut allergies
- Infant criteria
- Severe eczema, egg allergy, or both
- Rec: Strongly consider evaluation by sIgE measurement and/or skin prick test
- Mild-moderate eczema
- Rec: Introduce peanut-containing foods around 6mo
- No eczema or any food allergy
- Rec: Introduce peanut-containing foods at appropriate age in accordance with family preferences and culture practice
- Severe eczema, egg allergy, or both
19
Q
Cow’s milk allergy (CMA)
- Path: ___ Mediated
- Tx: ___ formula
- Ppx: ____ during the first 4-6mo after birth reduces the risk for cow milk protein allergy.
A
Cow’s milk allergy (CMA)
- Path: IgE Mediated
- Tx: Soy formula
- Ppx: Exclusive breastfeeding during the first 4-6mo after birth reduces the risk for cow milk protein allergy.
20
Q
Latex Allergy
- Development of latex allergy in children mainly occurs in those with a condition that gives them an increased exposure to latex-containing products (eg ____, congenital ____ problems).
- The main RFs for development of latex allergy in children with spina bifida are the number of surgeries, total serum IgE, presence of a VP shunt, and a personal hx of atopy.
- Greatest RF for all children (not just spina bifida) is multiple surgeries at an early age.
- Interestingly, several fruits and vegs cross-react with latex. While these pts can show a high IgE level to multiple fruits, vegs, and nuts, the main ones that show clinical relevance are: PKB PACT (PeeKaBoo PACT)
- __, __, __
- __, __, __, __
A
Latex Allergy
- Development of latex allergy in children mainly occurs in those with a condition that gives them an increased exposure to latex-containing products (eg spina bifida, congenital urologic problems).
- The main RFs for development of latex allergy in children with spina bifida are the number of surgeries, total serum IgE, presence of a VP shunt, and a personal hx of atopy.
- Greatest RF for all children (not just spina bifida) is multiple surgeries at an early age.
- Interestingly, several fruits and vegs cross-react with latex. While these pts can show a high IgE level to multiple fruits, vegs, and nuts, the main ones that show clinical relevance are: PKB PACT (PeeKaBoo PACT)
- Papaya, Kiwi, Banana (fruits)
- Potato, Avocado, Chestnut, Tomato (nuts and vegs)
21
Q
Allergy to penicillin
- Only 2% (1-3%) of individuals with a penicillin allergy are expected to react to cephalosporins
- Desensitization is a procedure using gradually increasing doses of penicillin to induce a _____ state of drug tolerance.
A
Allergy to penicillin
- Only 2% (1-3%) of individuals with a penicillin allergy are expected to react to cephalosporins
- Desensitization is a procedure using gradually increasing doses of penicillin to induce a TEMPORARY state of drug tolerance.
22
Q
ALLERGY TESTING
- All patients with reactions to penicillin antibiotics should receive skin allergy testing to confirm this allergy.
- 2 main forms of allergy testing: Positive results on both allergy skin testing and a serum allergy test only suggest sensitivity to a potential allergen, but a negative test is strong evidence against allergy to that substance.
- Pts must be off antihistamines for a minimum of ___ hours (4 half-lives of the medications) before skin testing bc these often blunt the response and give a false-negative reaction. Short-term steroids do not block skin testing for immediate hypersensitivity but do interfere with delayed hypersensitivity!
- Most medications should be stopped approx 5-7 days before performing test.
- Medications such as H1 blockers, H2 blockers (ranitidine), ___s, ____ antidepressants, and ________ should be avoided prior to performing test.
- TCAs have antihistaminergic properties, so these medications should be avoided as they can suppress allergy skin test results.
- ______ are a relative contraindication to allergy skin testing.
- Radioallergosorbent test (RAST): Serum allergen-specific IgE (sIgE) levels, which quantify IgE levels to specific foods.
- RAST is generally considered 2nd line by most allergists bc it is less sensitive compared to skin testing, and it measures IgE levels rather than directly measuring histamine release caused by IgE receptors signaling on mast cells. IgE levels alone do a poor job of predicting whether the pt has an actual allergy.
- Circumstances where RAST may be preferred
- Skin testing is inconvenient or difficult to perform
- Some patients cannot undergo skin testing bc of skin disease that would obscure wheal and flare results (eg extensive ____) or bc they cannot stop taking medications that suppress the skin test response
- Children less than ___yo
A
ALLERGY TESTING
- All patients with reactions to penicillin antibiotics should receive skin allergy testing to confirm this allergy.
- 2 main forms of allergy testing: Positive results on both allergy skin testing and a serum allergy test only suggest sensitivity to a potential allergen, but a negative test is strong evidence against allergy to that substance.
- Pts must be off antihistamines for a minimum of 72 hours (4 half-lives of the medications) before skin testing bc these often blunt the response and give a false-negative reaction. Short-term steroids do not block skin testing for immediate hypersensitivity but do interfere with delayed hypersensitivity!
- Most medications should be stopped approx 5-7 days before performing test.
- Medications such as H1 blockers, H2 blockers (ranitidine), TCAs, atypical antidepressants, and benzodiazepines should be avoided prior to performing test.
- TCAs have antihistaminergic properties, so these medications should be avoided as they can suppress allergy skin test results.
- Beta blockers are a relative contraindication to allergy skin testing.
- Radioallergosorbent test (RAST): Serum allergen-specific IgE (sIgE) levels, which quantify IgE levels to specific foods.
- RAST is generally considered 2nd line by most allergists bc it is less sensitive compared to skin testing, and it measures IgE levels rather than directly measuring histamine release caused by IgE receptors signaling on mast cells. IgE levels alone do a poor job of predicting whether the pt has an actual allergy.
- Circumstances where RAST may be preferred
- Skin testing is inconvenient or difficult to perform
- Some patients cannot undergo skin testing bc of skin disease that would obscure wheal and flare results (eg extensive atopic dermatitis) or bc they cannot stop taking medications that suppress the skin test response
- Children <2yo
23
Q
Food Protein-Induced Proctocolitis FPIAP / Cow Milk Protein Allergy / Allergic Colitis
- Path: ____ mediated type __ hypersensitivity reaction to very large milk protein, cause inflammatory response in distal colon
- Typically presents in the first few months after birth, with a mean age at onset of 2mo.
- Trigger: Milk and protein are the most common. Possible cross-reactivity with soy, egg, corn
- Pt:
- Enterocolitis with abdominal distension, diarrhea, ____ in infancy between 2-8 weeks of age.
- Tx:
- Eliminate exposure to culprit food
- For formula-fed infant, use ____ formula with protein partially broken down, such as Similac Alimentum. In some cases, an ___ formula will be needed.
- For breastfeeding infant, remove ___, all ___, and ___ in mother’s diet (for 2-4 weeks first as challenge). With complete elimination, bleeding typically clears within 1-2 weeks.
- With elimination of cow’s milk and dairy products from the maternal diet, infant’s symptoms should resolve within 3-4 days. If pts have persistent symptoms (ie persistent mucus and blood in stool), the next recommendation is to eliminate all soy, followed by each of the following: eggs, nuts, wheat, corn, strawberries, citrus, and chocolate.
- Prognosis: Generally spontaneously resolves before ___mo (50% by 6 months and 80-90% by 2 years). Planned reintroduction (around 9 mo)
A
Food Protein-Induced Proctocolitis FPIAP / Cow Milk Protein Allergy / Allergic Colitis
- Path: Non-IgE mediated type 4 hypersensitivity reaction to very large milk protein, cause inflammatory response in distal colon
- Typically presents in the first few months after birth, with a mean age at onset of 2mo.
- Trigger: Milk and protein are the most common. Possible cross-reactivity with soy, egg, corn
- Pt:
- Enterocolitis with abdominal distension, diarrhea, bloody bowel movement/rectal bleeding in infancy between 2-8 weeks of age.
- Tx:
- Eliminate exposure to culprit food
- For formula-fed infant, use extensively hydrolyzed formula with protein partially broken down, such as Similac Alimentum. In some cases, an amino acid-based formula will be needed.
- For breastfeeding infant, remove cow’s milk, all dairy (butter, cream), and soy (and eggs) in mother’s diet (for 2-4 weeks first as challenge). With complete elimination, bleeding typically clears within 1-2 weeks.
- With elimination of cow’s milk and dairy products from the maternal diet, infant’s symptoms should resolve within 3-4 days. If pts have persistent symptoms (ie persistent mucus and blood in stool), the next recommendation is to eliminate all soy, followed by each of the following: eggs, nuts, wheat, corn, strawberries, citrus, and chocolate.
- Prognosis: Generally spontaneously resolves before 12mo (50% by 6 months and 80-90% by 2 years). Planned reintroduction (around 9 mo)
24
Q
Food protein-induced enterocolitis syndrome (FPIES)
- Path: ____ mediated responses to food involving the small intestine and stomach
- Common triggers: cow’s milk, soy formulas, solid foods (rice, oat, grains, egg, vegs, poultry, fish)
- Pt: Typically occurs in infants between 1 week and 3 months of age.
- Profuse, protracted/repetitive vomiting, often with diarrhea (watery or bloody), abdominal distension, leading to dehydration and lethargy in the acute setting (often requiring rehydration), or weight loss and failure to thrive in a chronic form.
- Tx:
- May be medical emergency and requires _____
- Long-term management requires ____
A
Food protein-induced enterocolitis syndrome (FPIES)
- Path: Non-IgE mediated responses to food involving the small intestine and stomach
- Common triggers: cow’s milk, soy formulas, solid foods (rice, oat, grains, egg, vegs, poultry, fish)
- Pt: Typically occurs in infants between 1 week and 3 months of age.
- Profuse, protracted/repetitive vomiting, often with diarrhea (watery or bloody), abdominal distension, leading to dehydration and lethargy in the acute setting (often requiring rehydration), or weight loss and failure to thrive in a chronic form.
- Tx:
- May be medical emergency and requires IV fluid resuscitation.
- Long-term management requires dietary elimination and avoidance of causative food.
