"The first step in defining whether an anxiety disorder is due to a general medical condition is to establish the presence of a general medical condition that is often associated with the production of anxiety symptoms. The DSM-IV defines the most common endocrinological conditions associated with anxiety states as hyper- and hypothyroidism, hypoglycemia, pheochromocytoma, and hyperadrenocorticism. Anxiety may also occur following the exogenous administration of estrogens, progesterone, thyroid preparations, insulin, steroids and birth control pills. Popkin, in addressing the issue of endocrine disorders presenting with anxiety, suggests that anxiety states frequently occur in association with adrenal dysfunction, Cushing's Disease, Carcinoid syndrome, hyperparathyroidism, pseudohyperparathyroidism, hyperglycemia, hyperinsulinemia, pancreatic tumors, pheochromocytoma and thyroid diseases including hyperthyroidism, hypothyroidism and thyroiditis. Popkin cautions that prospective, carefully controlled studies on the etiology of anxiety in these conditions are lacking. The studies that are cited are almost exclusively case reports. He argues for more structured and careful research into the organic basis of these conditions.
Jefferson and Marshall identified hyperthyroidism, hypoglycemia, pheochromocytoma, and hyperadrenalism as the medical illnesses most often associated with anxiety symptoms and most frequently misdiagnosed initially as a primary anxiety disorder.
Hall et al in a study of medically induced anxiety disorder found thyroid disorders, i.e., hyper- and hypothyroidism and thyroiditis, to be the most frequent medical conditions misdiagnosed as primary anxiety disorder.11 Other common medical causes for anxiety in their study included hypoglycemia, Addison's and Cushing's Disease, hyper- and hypoparathyroidism, and diabetes mellitus. Rarer causes included various virilizing tumors and hypo- and hyperpituitarism.
Differentiating Anxiety Associated with Medical Illnesses from Primary Anxiety Diseases
After the clinician has established the presence of a general medical condition known to be associated with significant anxiety symptoms, he/she should undertake a careful and comprehensive assessment of the factors necessary to link the two conditions. Although there are no absolute guidelines, certain associations are helpful in establishing this connection. Are the onset of the symptoms temporally related? Is there a temporal association between the exacerbation or remission of the general medical condition and the enhancement or abatement of anxiety symptoms? Do anxiety symptoms disappear when the primary medical condition is treated? Are features that are atypical of a primary anxiety disorder present such as the usual age of onset, the initial presentation, type of onset, or an absence of family history? The clinician should also judge whether the disturbances that are present may be better accounted for by the presence of a primary anxiety disorder, a substance induced anxiety disorder, or an adjustment disorder brought on by the diagnosis of a primary medical condition.
In earlier work, reviewing patients who were felt to suffer from psychiatric symptoms caused by primary physical illness, Hall et al found that neurological and endocrine disorders were etiologically responsible for half of the medically induced anxiety symptoms encountered. In comparing these patients to patients with primary anxiety disorders seen in clinic, certain characteristics differentiated the patients with organic anxiety from those who suffered from a primary or psychogenic anxiety disorder. 1.) Patients with anxiety secondary to underlying medical illnesses tended to have disease characteristic fluctuations in the severity and duration of their anxiety or panic attacks. 2.) There was a clear cut association between the progression of their anxiety and their underlying disease. 3.) Medically induced anxiety disorders were most likely to have onset before the age of 18 or after the age of 35 in patients with a negative personal and family psychiatric history of anxiety or affective disorders and in patients who had not previously suffered from anxiety symptoms."