By Dr Ananya Mandal, MD
Fibromyalgia is a widespread pain condition that affects females more than men. It is further complicated by several associated symptoms and disorders. There are several conditions that mimic the symptoms of fibromyalgia syndrome and may be confused with fibromyalgia while making a diagnosis of the condition.
Excluding other conditions
According to the diagnostic guidelines from the ACR, diagnosis of fibromyalgia is based on finding the symptoms of the condition and excluding the other conditions with similar symptoms. In fact according to certain guidelines diagnosis of fibromyalgias is made on by exclusion.
Some of the differential diagnosis of fibromyalgia include:-
Hypothyroidism or underactive thyroid function
The patients with this condition often suffer from cold, dry skin and hair, constipation and fatigue. There may be widespread pain mimicking fibromyalgia as well. Thyroid function is to be tested while diagnosing fibromyalgia.
The thyroid-stimulating hormone (TSH) level may only be in the upper range of normal in most patients to cause symptoms. Patients with hypothyroidism are commonly managed with medications such as levothyroxine.
Medications that could induce muscle pain
Statins are cholesterol lowering agents. These drugs can cause widespread pain after a few weeks of commencing the medications. These patients can be successfully treated by reducing the dosage of the medication or changing to another cholesterol-lowering drug.
Certain parasite infestations like amoebiasis, fascioliasis or giardia may lead to widespread pain.
Fascioliasis is found in countries like Thailand, Bolivia, Ecuador, Egypt, Iran, Cuba, Peru, France, Spain, Germany, turkey etc. It is caused by the liver flukes. The symptoms of the infestation include abdominal pain, weight loss, muscle pain, fever and joint pain.
Most parasitic infestations can be treated effectively with medications including triclabendazole or praziquantel.
Myoadenylate deaminase deficiency
This is a condition where there is a muscle enzyme deficiency. In some cases this may cause widespread pain.
Deficiencies of vitamin B12, folic acid and ferritin maybe responsible for widespread pain as well as fatigue. Ferritin represents the tissue-bound non-essential iron stores in the body.
Vitamin B12 and folic acid deficiencies are associated with megaloblastic anemia as well that may lead to fatigue. By correcting the deficiencies, these patients may be treated effectively.
Several rheumatic diseases can mimic fibromyalgia. These include sero-negative rheumatoid arthritis, ankylosing spondylitis, Lyme disease, polymyalgia rheumatica and lupus. They have symptoms of widespread pain along with joint involvement. Most rheumatic diseases are treated with medication and physical therapy.
Adult growth hormone deficiency
This is caused by pituitary tumours, adenoma, certain infectious diseases such as HIV/AIDS or head injuries. Growth hormone normally stimulates the release of somatomedin C from the liver that maintains normal muscle health. Its deficiency causes fatigue, muscle weakness, stiffness, joint pain etc.
Depression and anxiety along with sleep disturbances commonly are associated with fibromyalgia. These may co-exist with the disease or may mimic its symptoms. These are treated with medications and behavioral therapies.
Myofascial pain syndrome
This is a distinctly different entity than fibromyalgia. This is a more localized pain problem. These patients may meet the ACR criteria and erroneously be diagnosed with fibromyalgia.
Other conditions that may mimic fibromyalgia include Hypermobility syndrome, Whiplash associated disorders (after physical trauma), widespread burns etc.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)
Last Updated: Jul 31, 2013