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PubMed This is a summary of 16 peer-reviewed journal articles Updated
Neurology

Understanding Your Labs and Tests for SREAT

At a Glance

SREAT is diagnosed using a combination of tests to identify brain inflammation and rule out other conditions. A complete workup includes blood tests for anti-TPO antibodies, a spinal tap, an EEG to check electrical activity, and a brain MRI. Thyroid hormone levels are often completely normal.

Navigating the labs and tests for SREAT (Steroid-responsive encephalopathy associated with autoimmune thyroiditis) can be frustrating because many of the results are “non-specific.” This means the tests might show that something is wrong with the brain, but they don’t always point directly to SREAT [1][1]. Understanding what these tests look for can help you advocate for a thorough evaluation.

Blood Tests: The Role of Thyroid Antibodies

The hallmark of SREAT is the presence of anti-TPO (thyroid peroxidase) or anti-TG (thyroglobulin) antibodies [2][3].

  • Markers, Not Causes: These antibodies are “markers” of an overactive immune system. Scientists are still studying whether they actually cause the brain inflammation or if they are just a “red flag” that the immune system is misfiring [4][5].
  • Titer vs. Severity: A very high “titer” (the amount of antibodies in your blood) does not necessarily mean your disease is more severe [6][1]. Some people have very high levels with mild symptoms, while others have low levels but are very ill.
  • Thyroid Function: Your actual thyroid hormone levels (TSH, T4) may be completely normal, as SREAT can occur in people who are euthyroid (normal thyroid function) [7][8].

CSF Analysis (Spinal Tap)

Testing your cerebrospinal fluid (CSF) is a critical step in the “diagnostic odyssey.” It helps doctors rule out infections and other types of brain inflammation [9][10].

  • Inflammatory Markers: Doctors look for elevated protein levels or oligoclonal bands, which are signs that the immune system is active inside the central nervous system [1][11].
  • Ruling Out Others: It is vital to test the CSF for other “neural antibodies” (like anti-NMDAR or LGI1) [1]. Some patients initially diagnosed with SREAT are later found to have a different form of autoimmune encephalitis that requires different long-term care [1][12].

Functional Brain Tests: EEG and MRI

Because SREAT affects the way the brain works, doctors use imaging and electrical tests to look for patterns [1].

  • EEG (Electroencephalogram): This test measures the electrical activity of your brain. In SREAT, it often shows generalized slowing, meaning the brain’s signals are moving slower than they should [13][1]. It may also show “epileptiform discharges,” which are electrical bursts that could lead to seizures [14].
  • MRI (Magnetic Resonance Imaging): Most people with SREAT actually have a normal brain MRI [1]. Sometimes, the scan might show non-specific “white matter changes” (small bright spots) that don’t point to a specific cause, or very rarely, temporary swelling in certain brain regions [15][16].

The Completeness Checklist

Before confirming a diagnosis of SREAT, the Graus 2016 criteria suggest that a complete workup should include:

  1. Serum Antibody Test: High titers of anti-TPO or anti-TG [1].
  2. Lumbar Puncture (Spinal Tap): To rule out infection and test for other neural antibodies [1][1].
  3. Brain MRI: To ensure there are no tumors, strokes, or other visible damage [1].
  4. EEG: To document any electrical slowing or seizure activity [1].
  5. Metabolic/Toxic Screen: To rule out vitamin deficiencies, organ failure, or drug-related issues that could mimic SREAT [9][10].

Ensuring every item on this list is checked helps prevent the high rate of misdiagnosis seen in this condition and ensures you are on the right path to recovery [1].

Common questions in this guide

What do high anti-TPO antibodies mean in SREAT?
High anti-TPO or anti-TG antibodies are markers of an overactive immune system, which is a hallmark of the condition. However, the exact amount of antibodies in your blood does not predict how severe your symptoms will be.
Can my thyroid function tests be normal if I have SREAT?
Yes, your actual thyroid hormone levels (like TSH and T4) can be completely normal. Many people with SREAT have normal thyroid function despite the presence of anti-thyroid antibodies.
Why do I need a spinal tap (CSF analysis) to diagnose SREAT?
A spinal tap checks for inflammatory markers like elevated protein or oligoclonal bands in the central nervous system. It is also crucial for ruling out other types of brain inflammation or infections that require entirely different treatments.
What does generalized slowing on my EEG mean?
Generalized slowing on an EEG means that the electrical signals in your brain are moving slower than normal. This is a common finding in SREAT and reflects how brain inflammation is affecting your cognitive function.
Is it normal for my brain MRI to be clear if I have SREAT?
Yes, most people with SREAT actually have a normal brain MRI. An MRI is still necessary during diagnosis to ensure your symptoms are not being caused by tumors, strokes, or other visible brain damage.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Are my anti-TPO levels being used as the primary reason for my diagnosis, or are there other objective test results?
  2. 2.Did my CSF (spinal fluid) show inflammatory markers like oligoclonal bands or high protein?
  3. 3.Were specific neural antibodies ruled out using both my blood and spinal fluid?
  4. 4.Can you explain what the 'slowing' on my EEG means for my cognitive symptoms?
  5. 5.Since my MRI was normal, what other tests did we use to confirm that my brain is actually inflamed?

Questions For You

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References

References (16)
  1. 1

    Brain dysfunction and thyroid antibodies: autoimmune diagnosis and misdiagnosis.

    Valencia-Sanchez C, Pittock SJ, Mead-Harvey C, et al.

    Brain communications 2021; (3(2)):fcaa233 doi:10.1093/braincomms/fcaa233.

    PMID: 34061124
  2. 2

    Hashimoto's encephalopathy: Follow-up data from neuropsychology, lumbar puncture, and FDG-PET.

    Lagström RMB, Østerbye NN, Henriksen OM, Høgh P

    Clinical case reports 2019; (7(9)):1750-1753 doi:10.1002/ccr3.2367.

    PMID: 31534741
  3. 3

    HASHIMOTO'S ENCEPHALOPATHY AS A RARE MANIFESTATION OF HYPOTHYROIDISM.

    Pak KJ, Rahim U, Romano J, Lee D

    The Journal of the Louisiana State Medical Society : official organ of the Louisiana State Medical Society 2015; (167(3)):154.

    PMID: 27159478
  4. 4

    Difficulties in the Diagnostics and Treatment of Hashimoto's Encephalopathy-A Systematic and Critical Review.

    Pempera N, Miedziaszczyk M, Lacka K

    International journal of molecular sciences 2024; (25(13)) doi:10.3390/ijms25137101.

    PMID: 39000209
  5. 5

    The Usefulness of Thyroid Antibodies in the Diagnostic Approach to Autoimmune Thyroid Disease.

    Vargas-Uricoechea H, Nogueira JP, Pinzón-Fernández MV, Schwarzstein D

    Antibodies (Basel, Switzerland) 2023; (12(3)) doi:10.3390/antib12030048.

    PMID: 37489370
  6. 6

    Hashimoto encephalopathy in pediatric patients: Homogeneity in clinical presentation and heterogeneity in antibody titers.

    Lee J, Yu HJ, Lee J

    Brain & development 2018; (40(1)):42-48 doi:10.1016/j.braindev.2017.07.008.

    PMID: 28784301
  7. 7

    When thyroid met brain: the enigma of steroid responsive encephalopathy associated with autoimmune thyroiditis a case report.

    Kotak P, Khurana K, Raut S, et al.

    Frontiers in immunology 2025; (16()):1504967 doi:10.3389/fimmu.2025.1504967.

    PMID: 39958334
  8. 8

    A Case of Euthyroid Steroid-Responsive Encephalopathy With Subacute Dementia.

    John R, Datta A, Ovallath S

    Cureus 2021; (13(9)):e17689 doi:10.7759/cureus.17689.

    PMID: 34513537
  9. 9

    An Intriguing Case of Delirium: Recognizing Steroid-Responsive Encephalopathy Associated With Autoimmune Thyroiditis.

    Surapaneni D, Sam N, Dasi SC, N B

    Cureus 2024; (16(9)):e70447 doi:10.7759/cureus.70447.

    PMID: 39473654
  10. 10

    Hashimoto's Encephalopathy: Clinical Features, Therapeutic Strategies, and Rehabilitation Approaches.

    Manocchio N, Magro VM, Massaro L, et al.

    Biomedicines 2025; (13(3)) doi:10.3390/biomedicines13030726.

    PMID: 40149702
  11. 11

    Hashimoto's Encephalopathy: Case Series and Literature Review.

    Chaudhuri J, Mukherjee A, Chakravarty A

    Current neurology and neuroscience reports 2023; (23(4)):167-175 doi:10.1007/s11910-023-01255-5.

    PMID: 36853554
  12. 12

    Hashimoto's Encephalopathy: A Rare Cause of Seizure-like Activity.

    Osman H, Panicker A, Nguyen P, Mitry M

    Cureus 2021; (13(4)):e14626 doi:10.7759/cureus.14626.

    PMID: 34040922
  13. 13

    SREAT presenting as decades of intractable seizures and isolated delusional episodes with clinical, laboratory, and EEG confirmation of treatment response.

    Tjong E, Gardner R, Peng YY

    SAGE open medical case reports 2019; (7()):2050313X19850051 doi:10.1177/2050313X19850051.

    PMID: 31205712
  14. 14

    Cerebellar syndrome as the presenting feature of Hashimoto encephalopathy.

    Choudhury C, Sahib A

    BMJ case reports 2024; (17(5)) doi:10.1136/bcr-2023-256365.

    PMID: 38806398
  15. 15

    Hashimoto's encephalopathy - presenting with epilepsia partialis continua and a frontal lobe lesion.

    Rukmangadachar LA, Dandapat S, Bit-Ivan EN, Peng YY

    Clinical case reports 2018; (6(1)):136-142 doi:10.1002/ccr3.1306.

    PMID: 29375853
  16. 16

    Hashimoto's Encephalopathy Masquerading as Rapidly Progressive Dementia and Extrapyramidal Failure.

    Aladdin Y, Shirah B

    Journal of neurosciences in rural practice 2022; (13(1)):101-104 doi:10.1055/s-0041-1741487.

    PMID: 35110927

This page explains tests and lab results for SREAT for educational purposes only and does not constitute medical advice. Your neurologist and endocrinologist are the best sources for interpreting your specific diagnostic reports.

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