Anxiety Disorder Due to Another Medical Condition 231
hensive assessment of multiple factors is ne cessary to make this judgment. Several aspects
of the clinical presentation should be consider ed: 1) the presence of a clear temporal asso-
ciation between the onset, exacerbation, or re mission of the medical condition and the anx-
iety symptoms; 2) the presence of features th at are atypical of a primary anxiety disorder
(e.g., atypical age at onset or course); and 3) evidence in the literature that a known phys-
iological mechanism (e.g., hyperthyroidism) ca uses anxiety. In addi tion, the disturbance
must not be better explained by a primar y anxiety disorder, a substance/medication-
induced anxiety disorder, or an other primary mental disorder (e.g., adjustment disorder). 
Associated Features Supporting Diagnosis
A number of medical conditions are known to  include anxiety as a symptomatic manifes-
tation. Examples include endocrine disease (e.g., hyperthyroidis m, pheochromocytoma,
hypoglycemia, hyperadrenocortisolism), cardiovascular disorders (e.g., congestive heart
failure, pulmonary embolism, arrhythmia such as atrial fibrillation), respiratory illness
(e.g., chronic obstructive pulmonary diseas e, asthma, pneumonia), metabolic distur-
bances (e.g., vitamin B12 deficiency, porphyria), and neurological illness (e.g., neoplasms,
vestibular dysfunction, encephalitis, seizure disorders). Anxiety due to another medical
condition is diagnosed when the medical cond ition is known to induce anxiety and when
the medical condition preceded the onset of the anxiety.
Prevalence
The prevalence of anxiety disorder due to an other medical condition is unclear. There ap-