Table 5.
Differential Diagnosis of Anaphylaxis
| Neurologic/autonomic dysregulation | Suggested tests |
|---|---|
| 1. Vasovagal and vasodepressor reactions | Clinical/ECG/BP |
| 2. Postural orthostatic tachycardia syndrome | Tilt table testing |
| 3. Seizure | EEG |
| 4. CVA | CT or MRI of the brain |
| Cardiovascular | |
| 1. Cardiogenic shock | TTE or RHC |
| 2. Hemorrhagic shock | Clinical bleeding/CBCa |
| 3. Vasodilatory/distributive/endotoxic shock | Bacterial cultures |
| 4. Capillary leak syndrome (hypovolemic shock) | Paraproteinemia |
| Endocrine/flushing | |
| 1. Carcinoid | Urine 5-HIAA |
| 2. Pheochromocytoma | Urine/serum catecholamines |
| 3. VIP-secreting tumors | VIP level |
| 4. Thyroid medullary carcinoma | Serum calcitonin |
| 5. Menopause (flushing, hot flashes) | LH, FSH, estrogen level |
| 6. Hypoglycemia | Blood sugar |
| Iatrogenic/drugs | |
| 1. Vancomycin (Red Man syndrome) | History/clinical |
| 2. Niacin (flushing) | History/clinical |
| 3. General anesthetics (hypotension) | History/clinical |
| Toxic | |
| 1. “Restaurant syndromes” | |
| a. Scombroidosis | History/tryptase/histamine |
| b. MSG | Toxicology |
| 2. Alcohol | EtOH level/osmolar gapb |
| 3. Sulfites | Clinical/toxicology |
| Hematologic/malignantc | |
| 1. Systemic mastocytosis | Tryptase, bone marrow |
| 2. Urticaria pigmentosa | Skin biopsy, tryptase |
| 3. Basophil leukemia | Bone marrow |
| 4. Acute promyelocytic leukemia with tretinoin treatment | Bone marrow |
| Immunologic | |
| 1. Bradykinin-mediated angioedema | C4, C1 inhibitor levels |
| Infection | |
| 1. Hydatid cyst (Echinococcus granulosus) | Clinical, serology, radiology |
| 2. Sepsis/septic shock | Blood cultures |
| Psychosomatic/functional disorders | |
| 1. Panic attack | Psychiatric consultation |
| 2. Factitious anaphylaxis | |
| a. Munchausen stridor | Psychiatric consultation |
| 3. Undifferentiated somatoform anaphylaxis | Psychiatric consultation |
| 4. Vocal cord dysfunction | Spirometry/flow volume loop |
C1 = complement 1; C4 = complement 4; CBC = complete blood count; CVA = cerebrovascular accident; EtOH = ethanol; FSH = follicle-stimulating hormone; 5-HIAA=urine 5-hydroxy indole acetic acid; LH=luteinizing hormone; MSG = monosodium glutamate; RHC = right heart catheterization; TTE = transthoracic echocardiogram; VIP = vasoactive intestinal peptide.
a
May be normal in acute loss of whole blood.
b
Osmolar gap allows for the assessment of other toxic alcohols.
c
Clonal and malignant mast cell disorders often demonstrate mutations of stem cell factor receptor, c-kit.