A medically determinable impairment is any impairment your doctor can diagnose based on anything more objective than just your description of your symptoms. This objective data can include any sort any visual evidence of a disability visible with x-ray, MRI, or the naked eye. It can also include the results of physical testing, e.g. the touch test for fibromyalgia. If your doctor has such objective evidence supporting her diagnosis of your symptoms, the Social Security Administration will almost always find that your impairment is "medically determinable."
However, even though your impairment must have objective medical evidence, your description of your symptoms can still be very important. Under some circumstances, patient description can be sufficient for the Social Security Administration’s definition of “medically determinable.” This is usually the case for disabilities that cannot be positively identified with objective evidence. For example, migraines can be ruled a “medically determinable impairment” based on patient description if the doctor can eliminate all other explanations for the patient’s symptoms.
Also, it is important to note that your doctor does not need any special knowledge about Social Security Administration regulation or the legal definition of “disabled.” Social Security Administration procedure even goes as far as to assume that your doctor knows nothing about the law behind finding someone disabled. Your doctor only needs to evaluate all the medical information about your impairment and give an opinion as to what you can reasonably do, and the Social Security Administration will make any and all legal evaluations. A Social Security disability representative can help inform your doctor about the complicated legal issues involved with a medical determination of your impairment.