An Unusual Patient with Hashimoto Thyroiditis, Features of Steroid-Responsive Encephalopathy Associated with Autoimmune Thyroiditis, and Concurrent Minimal Change Renal Disease

ABSTRACT Objective: To present an unusual patient with Hashimoto thyroiditis, encephalopathy with features of steroid-responsive encephalopathy associated with autoimmune thyroiditis (SREAT), and acute kidney injury secondary to minimal change renal disease. Methods: We present clinical, laboratory, imaging, electroencephalography, and renal histopathologic findings, and review the relevant literature for evaluation and treatment of SREAT. Results: A 53-year-old woman with a history of hypothyroidism on levothyroxine was admitted for progressive altered mental status and bizarre behavior for 3 weeks. On exam she was lethargic with myoclonic jerks, hypertonia, and hyperreflexia. Laboratory analyses showed thyroid-stimulating hormone of 0.057 μU/mL (normal, 0.27 to 4.0 μU/mL), free thyroxine of 1.5 ng/dL (normal, 0.7 to 1.5 ng/dL), triiodothyronine of 0.7 ng/mL (normal, 0.6 to 1.6 ng/dL), and elevated anti–thyroid peroxidase (>600 U/L) and antithyroglobulin (57.2 U/L) antibodies. The patient failed to improve with empiric antibiotics and anticonvulsants. She developed oliguric acute kidney injury with proteinuria requiring hemodialysis. Renal biopsy was consistent with minimal change disease and acute tubular necrosis. Further workup failed to identify infectious, structural, toxic, or neoplastic causes of the encephalopathy. SREAT was suspected and the patient was started on high-dose steroid therapy. Both the patient's mental status and renal function significantly improved with steroids and she was discharged home. Conclusion: We present, to our knowledge, the first case of Hashimoto thyroiditis associated with both encephalopathy with features of SREAT and minimal change renal disease. SREAT should be suspected in a patient with Hashimoto thyroiditis and unexplained encephalopathy that fails to respond to treatment. Abbreviations: anti-TPO anti–thyroid peroxidase; CNS central nervous system; CSF cerebrospinal fluid; fT4 free thyroxine; MRI magnetic resonance imaging; SREAT steroid-responsive encephalopathy associated with autoimmune thyroiditis; T3 triiodothyronine; TSH thyroid-stimulating hormone