Here is a interesting MEDLINE abstract about this topic:

Eur Arch Psychiatry Clin Neurosci. 2003 Dec; 253(6): 313-20.
Associations between anxiety disorders and physical illness.
Harter MC, Conway KP, Merikangas KR.

OBJECTIVE: In contrast to the literature on the association of depression with medical illness, less is known about the comorbidity among anxiety and somatic disorders. Although associations between anxiety disorders and medical illnesses have been reported, prior studies have not adjusted for the effects of gender, substance abuse/dependence, and depression. This study examined the patterns of co-occurence of anxiety disorders and physical illnesses.

METHOD: A total of 262 probands were selected from treatment settings or were randomly recruited from the community. DSM-III-R diagnoses were obtained based on direct interview (SADS) or family history information, and lifetime history of numerous medical illnesses were obtained.

RESULTS: Patients with a lifetime anxiety disorder reported higher rates of several medical illnesses than did persons without anxiety. After controlling for the effects of gender, comorbid substance abuse/dependence and/or depression, significant associations were found between anxiety disorder and cardiac disorders (OR = 4.6), hypertension (OR = 2.4), gastrointestinal problems (OR = 2.4), genitourinary disorders (OR = 3.5), and migraine (OR = 5.0). A similar pattern was observed for probands with panic or generalized anxiety disorder (GAD).

CONCLUSIONS: Anxiety disorders are often associated with a specific pattern of somatic illnesses like cardiac disorders, hypertension, gastrointestinal problems, difficulties getting pregnant, asthma, migraine, etc.; individuals with both anxiety disorders and medical illness need therefore to be evaluated carefully for cooccurence.