Updated: 12/13/2019

Urticaria

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Snapshot
  • APhoto45-year-old woman with a history of systemic lupus erythematous presents to her dermatologist’s office with hives. She complains that this is the “worst it’s ever been.” She has been having episodes of itchy rashes on and off for about 6 months now. On physical exam, her entire back is covered with raised, red wheals. Some are annular. The lesions are blanching and intensely pruritic. She denies any difficulty breathing or any GI symptoms. She has a history of childhood asthma and hypothyroidism, currently on levothyroxine. The lesions usually resolve spontaneously, but this episode is particularly pruritic. She is given an anti-histamine.
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
  • Timeline
    • acute is < 6 weeks
    • chronic is > 6 weeks
  • Triggers of acute urticaria
    • 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
    • more likely to be associated with autoimmunity
  • Etiology identified in 40-60% of acute cases and 10-20% in chronic cases
  • Many different types of urticarial with wide range of severity
    • IgE-mediated
    • chemical-induced
    • cold-induced
    • autoimmune
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 
      • linear
      • annular
      • serpiginous
      • can coalesce
    • can occur anywhere on the body
    • dermotographism (urticaria from light scratching)
      • indicates very sensitive skin
    • assess for angioedema of lips
    • assess for mucosal lesions
    • may have neutrophilic vasculitis
      • painful as well as pruritic
      • purpuric and hyperpigmented lesions
      • systemic systoms such as arthralgias and GI symptoms
Evaluation
  • Labs or biopsy not indicated for acute urticaria unless diagnosis is unclear
  • ↑ IgE
  • For chronic or recurrent urticarial
    • test ESR, TSH, and ANA
  • Biopsy 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
      • second generation anti-histamines are less sedating and have negligible anticholinergic effects when compared to first generation anti-histamines
  • For urticarial vasculitis
    • NSAIDs
    • methotrexate
    • colchicine
    • dapsone
Prognosis, Prevention, and Complications
  • Prognosis
    • most resolve spontaneously
  • Prevention
    • avoid known triggers
    • take second generation anti-histamine daily
  • Complications
    • life-threatening angioedema
    • neutrophilic vasculitis
      • associated with arthritis, renal disease, and hypercomplementemia
      • often lasts > 24 hours
 

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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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(M3.DM.16.41) A 12-year-old female is brought into your office by her mother. She states that the child was recently diagnosed with "strep throat" and was prescribed penicillin for treatment. Over the last day, the child has suddenly developed a rash that is pruritic and erythematous, as seen in Figure A. The child has a history of asthma. On exam, her vitals are within normal limits. There are areas of erythema along with reddish-whitish papules and plaques (mainly located on her extremities). What is the most important intervention for this child? Review Topic | Tested Concept

QID: 102795
FIGURES:
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Continue current drug regimen

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Corticosteroids

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Antihistamines

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Beta-adrenergic agonists

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Discontinue current drug regimen and switch to another antibiotic

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L 3 E

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