|MadSci Network: Medicine|
Much of this information is from the DSM IV (Diagnostic and Statiscal Manual of Mental Disorders, 4th edition, published by the American Psychiatric Association), and provided to me by a psychiatric advanced practice nurse.
Somatization disorder is characterized by physical complaints occurring over period of several years and resulting in treatment seeking and impairment in functioning. For a diagnosis of somatization disorder, the patient must have 4 pain symptoms, 2 gastrointestinal symptoms, 1 sexual symptom, and 1 pseudo-neurological symptom, AND after a full medical work-up, either the symptoms cannot be fully explained by medical condition or symptoms are in excess of what is expected given the medical condition.
Conversion disorder is 1 or more symptoms affecting voluntary motor or sensory function (suggesting a neurological or medical condition), but psychological factors are judged to be associated with symptoms because the symptoms is preceded by a conflict or other stressor. The symptoms are not intentionally produced, cannot be fully explained by medical condition, and cause significant distress or impairment. A rather graphic example of conversion disorder is found at http://www.healthsci.utas.edu.au/psychiatry/conv_diso.htm
The distinction between the two conditions is that conversion disorder is EXPLICITLY identified as a response to conflict or stress, and the symptoms are related to motor or sensory functions ONLY.
Hypochondriasis is quite different. This is a preoccupation with fears of having, or the idea that one has, a serious disease although symptoms may be mild or nonexsistant, and symptoms may not cause noticable impairment although the patient may experience significant distress. This fear persists despite appropriate medical evaluation and reassurance.
More information on Somatoform disorders is available in the Merck Manual of Diagnosis and Therapy at http://www.merck.com/pubs/mmanual/section15/chapter186/186a.htm and from the University of Utah at http://www.psych.utah.edu/psych3400/somat.html
Try the links in the MadSci Library for more information on Medicine.