Differential Diagnosis

The patient's symptoms of fatigue and inability to lose weight, combined with the laboratory results, suggest a thyroid-related issue. Here's a breakdown of the differential diagnosis:

• Single most likely diagnosis
  • Subclinical Hypothyroidism: The patient's TSH is slightly elevated at 2.08, which is still within the normal range but on the higher end, and the Thyroperoxidase Antibodies are elevated, indicating autoimmune thyroiditis. The T3 and T4 levels are within normal limits, but the presence of antibodies and the patient's symptoms suggest subclinical hypothyroidism.
• Other Likely diagnoses
  • Euthyroid Sick Syndrome: The patient's T4 is at the lower end of the normal range, which could be seen in euthyroid sick syndrome, a condition where thyroid hormone levels are altered due to systemic illness, but the thyroid gland itself is normal.
  • Autoimmune Thyroiditis (Hashimoto's Thyroiditis): The elevated Thyroperoxidase Antibodies suggest an autoimmune component, which is consistent with Hashimoto's thyroiditis. However, the thyroid hormone levels are currently within normal limits.
• Do Not Miss
  • Pituitary Dysfunction: Although less likely, pituitary dysfunction (e.g., a pituitary tumor) could cause altered thyroid hormone levels and should be considered, especially if other symptoms such as headaches or visual disturbances are present.
  • Thyroid Hormone Resistance: A rare condition where the body's tissues are resistant to thyroid hormones, which could present with normal or slightly altered thyroid hormone levels but with symptoms of hypothyroidism.
• Rare diagnoses
  • Familial Dysalbuminemic Hyperthyroxinemia: A rare condition characterized by abnormal binding of T4 to albumin, leading to altered T4 levels, but this would not explain the elevated TSH or Thyroperoxidase Antibodies.
  • Thyroid Hormone Abnormalities due to Other Systemic Diseases: Certain systemic diseases (e.g., liver disease, kidney disease) can alter thyroid hormone levels, but these would typically be associated with other significant clinical findings and abnormalities in other laboratory tests.