Differential Diagnosis for Elevated TSH and T4 with Normal T3
Single Most Likely Diagnosis
- Subclinical Hyperthyroidism with Thyroid Hormone Resistance: This condition is characterized by elevated TSH and T4 levels, with normal T3 levels. The thyroid hormone resistance leads to an increase in T4 production, which in turn increases TSH levels.
Other Likely Diagnoses
- TSH-producing Pituitary Adenoma: A rare type of pituitary tumor that secretes TSH, leading to elevated TSH and T4 levels.
- Familial Dysalbuminemic Hyperthyroxinemia: A genetic disorder that affects the binding of T4 to albumin, leading to elevated T4 levels and normal T3 levels.
- Thyroid Hormone Resistance due to Thyroid Hormone Receptor Mutations: Mutations in the thyroid hormone receptor can lead to resistance to thyroid hormone, resulting in elevated TSH and T4 levels.
Do Not Miss Diagnoses
- Pituitary Macroadenoma with TSH Hypersecretion: A large pituitary tumor that secretes TSH, which can lead to visual field defects, headaches, and other neurological symptoms if left untreated.
- Thyroid Storm: Although the T3 level is normal, thyroid storm is a life-threatening condition that requires immediate attention. It can occur in patients with untreated or undertreated hyperthyroidism.
Rare Diagnoses
- Struma Ovarii: A rare ovarian tumor that produces thyroid hormones, leading to elevated T4 levels and normal T3 levels.
- Familial Euthyroid Hyperthyroxinemia: A rare genetic disorder that affects the metabolism of thyroid hormones, leading to elevated T4 levels and normal T3 levels.
- Iodine-induced Hyperthyroidism: Excessive iodine intake can lead to hyperthyroidism, especially in patients with pre-existing thyroid disease.