I have hypothyroid and diabetes.
They are now testing for suspected rheumatoid arthritis triggered by my last pregnancy - though I am surely hoping it is not.
These things can definitely come in clusters.
I really believe once autoimmune becomes an issue the immune system is very hard to recover
I have, both Hashimoto's and Pernicious Anemia (unable to absorb B12). They are dealt with separately. Hashimoto's is not treated "per se"; it's the resulting hypothyroidism that's treated with replacement hormones. Pernicious Anemia is treated with vitamin B12 shots; usually, monthly, but in my case, weekly.
Once a person has one autoimmune the chances are greater that they will have another. In addition, autoimmunes tend to run in families, but family members don't always have the same ones...... for instance, I have Hashi and PA, my son has Type I diabetes and my daughter has lupus. Both of them are likely to end up with one or more, other autoimmunes. I suspect that my daughter has Hashi, but she won't bring me labs, so I can't prove it. I suspect that she isn't getting the proper tests.
I have both autoimmune thyroid Graves and Hashimoto along with Vitiligo however, my skin condition is very minimal and is definately a secondary issue. Commonly an autoimmune thyroid will have a cluster of three autoimmune diseases form. some patients don't see - or are not diag with others some can have more than three.
Here's a good article to start some reading.
http://www.ncbi.nlm.nih.gov/pubmed/21905597
About 25% of patients with autoimmune diseases have a tendency to develop additional autoimmune diseases. Three or more autoimmune diseases is known as multiple autoimmune syndrome (MAS). The MAS classifications are helpful if signs of another autoimmune disease emerges.
Type 1 MAS: myasthenia gravis, thymoma, polymyositis, giant cell myocarditis.
Type 2 MAS: Sjögren's syndrome, rheumatoid arthritis, primary biliary cirrhosis, scleroderma, autoimmune thyroid disease.
Type 3 MAS: autoimmune thyroid disease, myasthenia gravis and/or thymoma, Sjögren's syndrome, pernicious anaemia, idiopathic thrombopenic purpura, Addison's disease, type 1 diabetes mellitus, vitiligo, autoimmune haemolytic anaemia, systemic lupus erythematosus, dermatitis herpetiformis.
The immune system marker HLA-B8 and/or DR3 or DR5 seems to be an important factor in Type 3 MAS.
Other conditions found in various combinations in MAS:
Type 1 MAS: pemphigus, autoimmune thyroid disease.
Type 2 MAS: chronic active hepatitis, systemic lupus erythematosus, pemphigus, bullous pemphigoid, autoimmune haemolytic anaemia, idiopathic thrombopenic purpura, alopecia areata, Addison's disease.
Type 3 MAS: acquired primary hypogonadism, hypophysitis, rheumatoid arthritis, primary biliary cirrhosis, relapsing polychondritis, multiple sclerosis, chronic active hepatitis, ulcerative colitis, scleroderma.