7618 Thyroid Nodules, Normal Thyroid Levels, and Chronic Anxiety: A Case for Sub-Clinical Toxic Multinodular Goiter

Abstract Disclosure: C.M. Barrera: None. Introduction: Chronic anxiety and panic disorders, as described in the Diagnostic and Statistical Manual of Mental Disorders (DSM-V), are the most common psychiatric conditions. Hyperthyroidism is a known cause of both chronic anxiety and panic disorder. Case 1: A 36-year-old overweight Latin female is referred for evaluation of multiple thyroid nodules. The thyroid ultrasound was heterogeneous, with multiple bilateral nodules. In her history, the patient has chronic anxiety with panic attacks resulting in frequent emergency room visits. The TSH and T4 levels were TSH 0.59 mIU/L (0.40-4.5) and T4 10.7 mcg/dL (5.1-11.9). An I[1]23- Thyroid Scan showed a hot nodule with mild suppression and an uptake of 31.8% (The top limit is 35%). The patient started methimazole 2.5 mg daily, and after two months, her chronic anxiety and panic attacks resolved. Post-methimazole TSH rose to 1.18 mIU/L, and T4 10.0 mcg/dL and she has weaned off anxiety medications. Case 2: A 49-year-old overweight Latin female is referred for increased thyroid nodules. She complained of six months of tachycardia and anxiety. The TSH and T4 levels were TSH of 0.828 mIU/L (0.40-4.5) and T4 of 7.9 mcg/dl (4.5-12.0). An I[1]23-Thyroid Scan showed no dominant hot or cold nodules, with an uptake of 36.4% (The top limit is 35%, within normal error limits). She started methimazole 5 mg daily, resolving her tachycardia and anxiety within five weeks. Post-methimazole TSH was 1.64 mIU/L (0.45-4.5), and T4 6.7 mcg/dL (4.5-12.0). Case 3: A 60-year-old overweight Latin female is referred for evaluation of multiple thyroid nodules of ten years. She complained of chronic anxiety and panic attacks for two years. The TSH and T4 were normal at TSH 0.36 mIU/L (0.35- 5.50) and T4 9.7 mcg/dL (4.5-10.9). The thyroid ultrasound showed multiple bilateral nodules. An I[1]23-Thyroid Scan showed a suspected hot nodule without appreciable suppression and an uptake of 33% (The top limit is 35%). The patient started methimazole 5 mg daily. After eight weeks, she reported the resolution of most of her chronic anxiety with post-methimazole TSH 2.39 mIU/L and T4 7.1 mcg/dL (4.5-12.0). Discussion: The normal range of TSH, typically from 0.4-4.5 mIU/L, is calculated by measuring the TSH levels among a normal population. The group range then determines the laboratory reference range. This contrasts with individual values, which have a narrower range, suggesting that each person has a unique thyroid level. This suggests that TSH levels at the extremum, associated with hyperfunctioning nodules contributing to a rise in uptake, may not be normal for that patient and may explain the anxiety and other symptoms. Learning Points: Evolving multiple autonomous thyroid nodules lowers TSH levels while raising thyroid uptake. Symptoms of chronic anxiety and panic attacks can predate abnormal thyroid levels and resolve with low-dose methimazole. Presentation: 6/1/2024