Table 1.

Etiologies of olfactory dysfunctions.

Sinonasal conditions

Upper respiratory infection (especially viral), allergic rhinitis, chronic rhinosinusitis, nasal polyps

Head trauma

Damage to cribriform plate, shearing forces, intracranial damage, facial trauma

Neurodegenerative disorders

Parkinson disease, parkinsonism, Alzheimer disease, mild cognitive impairment, multiple sclerosis

Medications

Chemotherapy, angiotension-converting enzyme inhibitors, angiotensin receptor blockers, dihydropyridine calcium channel blockers, diuretics, intranasal zinc, antimicrobials (macrolides, terbinafine, fluoroquinolones, protease inhibitors, griseofulvin, penicillins, tetracyclines, nitromidazoles, antiarrhythmics, antithyroid agents, antidepressants, anticonvulsants, lipid-lowering agents)

Toxins or intoxicants

Alcohol, cocaine, ammonia, hairdressing chemicals, gasoline, formaldehyde, paint solvents, welding agents, benzene, sulfuric acids, cadmium, acrylates, iron, lead, chromium

Chronic medical conditions

Renal of hepatic failure, diabetes mellitus, cancer, human immunodeficiency virus

Structural or mechanical conditions

Ischemic stroke, subarachnoid or intracranial hemorrhage, brain or sinonasal tumor

Nutritional deficiencies

Malnutrition, pernicious anemia, deficiencies in vitamin A/B6/B12, niacin, zinc or copper

Postsurgical state

Nasal surgery (septal or sinus), total laryngectomy, pharyngectomy, tonsillectomy

Post-radiation (especially to head and neck area)

Congenital conditions

Kallmann syndrome

Phychiatric conditions

Anorexia nervosa, major depressive disorder, bipolar disorder, schiznophrenia

Endocrine conditions

Pregnancy, hypothyroidism, Addison disease, Cushing syndrome

Autoimmune/inflammatory conditions

Sjögren syndrome, systemic lupus erythematosus, sarcoidosis, herpes encephalitis