Differential Diagnosis
- Single most likely diagnosis
- Thyroid Storm: This condition is characterized by an excessive production of thyroid hormones, leading to symptoms such as atrial fibrillation (Afib), which is consistent with the patient's repeated episodes of Afib. The low TSH and high T3 levels also support this diagnosis, as they indicate hyperthyroidism.
- Other Likely diagnoses
- Graves' Disease: This is an autoimmune disorder that leads to hyperthyroidism, which could explain the patient's low TSH and high T3 levels. The normal thyroid ultrasound does not rule out this diagnosis, as the thyroid gland may appear normal in the early stages of the disease.
- Toxic Multinodular Goiter: This condition is characterized by the presence of multiple nodules in the thyroid gland that produce excess thyroid hormones, leading to hyperthyroidism. Although the thyroid ultrasound is normal, it is possible that the nodules are not yet visible or are not causing significant thyroid enlargement.
- Thyroiditis: This is an inflammation of the thyroid gland that can lead to the release of stored thyroid hormones, causing hyperthyroidism. The normal thyroid ultrasound does not rule out this diagnosis, as the inflammation may not be visible on imaging.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Cardiac Causes of Afib: While the patient's thyroid hormone levels suggest a thyroid-related cause of Afib, it is essential to rule out cardiac causes, such as cardiomyopathy or cardiac valve disease, which could be life-threatening if left untreated.
- Pheochromocytoma: This is a rare tumor of the adrenal gland that can produce excess catecholamines, leading to symptoms such as Afib and hyperthyroidism. Although unlikely, this diagnosis could be life-threatening if missed.
- Rare diagnoses
- Struma Ovarii: This is a rare ovarian tumor that can produce thyroid hormones, leading to hyperthyroidism. Although unlikely, this diagnosis could explain the patient's symptoms and thyroid hormone levels.
- Familial Dysalbuminemic Hyperthyroxinemia: This is a rare genetic disorder that affects the binding of thyroid hormones to albumin, leading to elevated T3 and T4 levels. Although unlikely, this diagnosis could explain the patient's thyroid hormone levels and symptoms.