Thought this article was interesting Confusing Medical Ailments With Mental Illness I couldn't find it posted already.
Studies have suggested that medical conditions may cause mental-health issues in as many as 25% of psychiatric patients and contribute to them in more than 75%.
Untangling cause and effect can challenge even seasoned clinicians, and the potential for missed diagnoses is growing these days, said Dr. Schildkrout, who has more than 25 years of clinical practice in the Boston area. Most mental-health counselors rely on primary-care doctors to spot medical issues, but those physicians are increasingly time-pressed and may not know their patients well. Neither do the psychiatrists who mainly write prescriptions and see patients only briefly, she said in an interview.
Common culprits include under- or over-active thyroid glands, which can cause depression and anxiety, respectively. Deficiencies of vitamins D, B-12 and folate, as well as hormonal changes and sleep disorders have also been linked to depression.
Diabetes, lupus and Lyme disease can have a variety of psychiatric symptoms, as can mercury and lead poisoning and sexually transmitted diseases. Many medications also list mood changes among their side effects, and substance abuse is notorious for causing psychiatric problems.