Updated: 11/16/2018

Urticaria

Topic
Review Topic
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Questions
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Evidence
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Snapshot
  • A 25-year-old man presents with an itchy rash on his chest wall. He denies any exposures to insects and denies any previous allergies. He recently had an upper respiratory infection. Physical exam shows blanching, raised, edematous annular lesions that are well-circumscribed. Some lesions are coalesced. This is his first episode of this itchy rash. He denies any other symptoms.
Introduction
  • Pruritic inflammation of the skin commonly known as “hives”
  • Characterized by superficial, localized edema and erythema
  • Epidemiology
    • most frequent dermatologic disorder seen in the emergency room
  • Pathogenesis
    • involving dermis and epidermis
    • mast cell and basophil release of vasoactive substances
      • histamine, bradykinin, and prostaglandins
      • intense pruritus is from histamine in the dermis
    • type I hypersensitivity reaction 
  • Triggers of acute urticarial (< 6 weeks)
    • drugs
    • food
    • viral infection
    • recent illness
    • insect bite
    • emotional stress
    • cold or heat
    • alcohol ingestion
    • pregnancy
    • exposure to other allergens (pet dander, dust, mold, or chemicals)
    • sun
  • Chronic urticarial is usually idiopathic (> 6 weeks)
  • Etiology identified in 40-60% of acute cases and 10-20% in chronic cases
Presentation
  • Symptoms
    • history of previous urticaria
    • pruritus
    • lasts a few hours
    • resolves spontaneously
  • Physical exam
    • well-circumscribed erythema and edema on skin
    • blanching, raised, and palpable wheals
    • can occur on anywhere on the body
    • dermotographism (urticaria from light scratching)
      • indicates very sensitive skin
Evaluation
  • Labs or biopsy not indicated for acute urticarial unless diagnosis is unclear
  • ↑ IgE
  • For chronic or recurrent urticarial
    • test ESR, TSH, and ANA
  • Histology of lesion
    • dermal edema
    • lymphatic channel dilation
Differential Diagnosis
  • Hereditary angioedema
  • Contact dermatitis 
  • Multiple insect bites
  • Erythema multiforme
Treatment
  • If known, discontinue offending agent
  • If concern for airway compromise
    • epinephrine
  • Anti-histamines
    • second generation > first generation
Prognosis, Prevention, and Complications
  • Prognosis
    • most resolve spontaneously
  • Prevention
    • avoid known triggers
    • take second generation anti-histamine daily
  • Complications
    • life-threatening angioedema
 

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Questions (3)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
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(M1.MK.28) A 35-year-old woman comes to see her primary care physician, because she is concerned about her skin. She states that she noticed a rash after recently starting a new medication. The rash appears as numerous pale, red, raised, itchy bumps on both of her legs, as seen in Figure A. What histologic pattern is most consistent with this patient's dermatologic condition? Review Topic

QID: 103821
FIGURES:
1

Dermal edema

57%

(65/115)

2

Spongiosis

31%

(36/115)

3

Hyperkeratosis

6%

(7/115)

4

Acantholysis

0%

(0/115)

5

Acanthosis

5%

(6/115)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 1

(M1.MK.1) A 17-year-old female accidentally eats a granola bar manufactured on equipment that processes peanuts. She develops type I hypersensitivity-mediated histamine release, resulting in pruritic wheals on the skin. Which of the following layers of this patient's skin would demonstrate histologic changes on biopsy of her lesions? Review Topic

QID: 101309
1

Stratum corneum

18%

(37/201)

2

Stratum granulosum

16%

(32/201)

3

Stratum spinosum

12%

(25/201)

4

Stratum basale

9%

(18/201)

5

Dermis

43%

(87/201)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 5
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