Findings	Diagnoses to consider
History
Sudden loss of function	Head trauma (less likely with taste loss), cerebrovascular accident, acute upper respiratory infection, psychiatric condition
Intermittent loss of function	Inflammatory process (e.g., allergy, infection, chemical exposure)
Gradual loss of function	Nasal polyps, chronic upper respiratory infection
Difficulty passing air through nose	Obstruction secondary to polyps, inflammation or fracture
Physical examination
Rhinorrhea	Rhinitis (e.g., allergy, infection, irritation) head trauma (fracture of cribiform plate)
Intranasal mass lesion	Polyps, neoplasm or tumor
Oral or perioral skin lesion	Viral infection (e.g., herpes simplex)
White plaque on tongue	Candidiasis, human immunodeficiency virus infection, acquired immunodeficiency syndrome, immunocompromised state, leukoplakia
Facial droop	Bell's palsy
Memory impairment	Alzheimer's disease
Motor findings (e.g., bradykinesia, cogwheel rigidity, akathisia, tremor, instability, ataxia, weakness)	Parkinson's disease, multiple sclerosis
Laboratory tests
Low hematocrit, low hemoglobin level	Anemia, cancer, malnutrition
Altered red cell indexes	Nutritional deficiencies (e.g., vitamin B12)
Elevated white blood cell count	Infection
Elevated blood urea nitrogen level, elevated creatinine level	Renal disease
Elevated blood glucose level	Diabetes mellitus
Elevated liver enzyme level	Viral hepatitis, liver disease
Elevated bilirubin level, elevated alkaline phosphatase level	Liver disease
Elevated prothrombin time	Malnutrition, liver disease
Altered thyroid function tests	Thyroid disease
Elevated erythrocyte sedimentation rate	Sjögren's syndrome, systemic lupus erythematosus
Elevated eosinophil count	Allergy
Elevated immunoglobulin E level	Allergy