Diagnosis and Misdiagnosis of SREAT: Why It's Hard to Pin Down

Getting a diagnosis of SREAT (Steroid-responsive encephalopathy associated with autoimmune thyroiditis) is often a relief, but it is also a medically complex process. Because there is no single test that can “prove” you have SREAT, doctors must work like detectives to rule out every other possibility first ^[1][2].

The Mayo Clinic Warning: A High Rate of Misdiagnosis

One of the most important things to understand about SREAT is how often it is misdiagnosed. A major study by the Mayo Clinic found that 73% of patients who were referred to them with a suspected diagnosis of SREAT actually had something else entirely ^[1].

Do not panic at this statistic. The reason this number is so high is precisely why medical guidelines were created: to ensure doctors perform a deep, thorough investigation rather than jumping to conclusions. Proper evaluation protects you from misdiagnosis.

Common conditions that were initially mistaken for SREAT in that study included:

• Functional Neurological Disorder (FND): A condition where the brain’s “software” has trouble sending and receiving signals ^[1].
• Neurodegenerative Diseases: Such as early-onset Alzheimer’s or other dementias ^[1][3].
• Primary Psychiatric Disorders: Like severe depression or bipolar disorder ^[1][4].
• Other Autoimmune Encephalitides: Brain inflammation caused by specific antibodies (like NMDA-R or LGI1) that require different treatments ^[1].

Why Antibodies Aren’t Enough

Many patients are told they have SREAT simply because they have high levels (a high titer) of anti-TPO or anti-TG antibodies in their blood. A titer is simply a laboratory measurement of how much of a specific antibody is present.

However, modern medical consensus states that antibodies alone are not enough for a diagnosis ^[1][1]. Approximately 13% of the healthy population has these thyroid antibodies without ever developing brain symptoms ^[1]. Furthermore, the titer of your antibodies does not match how sick you feel—someone with very high antibodies might have mild symptoms, while someone with low antibodies might be very ill ^[5].

The Graus 2016 Consensus Criteria

To protect patients from misdiagnosis, experts developed the Graus criteria. To be diagnosed with “Probable SREAT,” a patient must meet all of the following formal criteria ^[1][1]:

1. Encephalopathy: Clear signs of brain dysfunction, such as seizures, hallucinations, stroke-like episodes, or sudden memory loss ^[1].
2. Thyroid Antibodies: High levels of anti-TPO or anti-TG ^[1].
3. Exclusion of Others: Doctors must prove it isn’t an infection, a metabolic issue, or a different type of autoimmune encephalitis ^[1][2].
4. Normal or Non-specific MRI: The brain scan should not show major damage that would point to a different disease ^[1].

The Role of Steroids in Diagnosis

While an “objective steroid response” is not formally listed in the Graus 2016 criteria as a strict prerequisite (to avoid delaying treatment), it is a crucial step for clinical management and diagnostic validation.

It is common for people to feel “better” or more energetic when taking steroids—this is often called a “steroid buzz.” However, to validate a SREAT diagnosis, the response must be objective ^[1]. This means your doctor should see a measurable change, such as a cleaner EEG (brain wave test), improved scores on a memory test, or the complete stopping of seizures ^[1][1]. If the only change is feeling more energetic, your doctor may need to look closer at other possible causes ^[1].