Differential Diagnosis for Abnormal TSH with Drive Line Infection and Fluctuating BP

Single Most Likely Diagnosis

• Sepsis: The presence of a drive line infection, which is a type of central line-associated bloodstream infection, combined with fluctuating blood pressure, strongly suggests sepsis. Sepsis can lead to fluctuations in thyroid function tests, including TSH levels, due to the systemic inflammatory response.

Other Likely Diagnoses

• Thyroid Dysfunction due to Sepsis or Critical Illness: Critical illness, including sepsis, can cause changes in thyroid function tests, often presenting as euthyroid sick syndrome (also known as non-thyroidal illness syndrome), where TSH levels can be abnormal but do not necessarily indicate primary thyroid disease.
• Adrenal Insufficiency: This condition can cause fluctuating blood pressure and may also affect thyroid function tests. The stress of infection can unmask adrenal insufficiency, leading to hypotension and potentially abnormal TSH levels.
• Medication-Induced Thyroid Dysfunction: Certain medications, especially those used in the treatment of infections or in critically ill patients, can affect thyroid function tests.

Do Not Miss Diagnoses

• Pheochromocytoma: Although rare, pheochromocytoma can cause fluctuating blood pressure and may also affect thyroid function tests indirectly through systemic effects. Missing this diagnosis could be catastrophic due to the potential for severe hypertensive crises.
• Thyroid Storm: A life-threatening condition that requires immediate recognition and treatment. It can be precipitated by infection and is characterized by extreme hyperthyroidism symptoms, which might include fluctuating blood pressure.
• Addisonian Crisis: An acute adrenal insufficiency crisis can present with hypotension, infection, and potentially abnormal thyroid function tests due to the critical illness.

Rare Diagnoses

• Thyroiditis: Inflammation of the thyroid gland, which can be caused by infection, although this is less common. It can lead to abnormal TSH levels and might be associated with systemic symptoms including fever and malaise.
• Multiple Endocrine Neoplasia (MEN) Syndromes: These are rare genetic disorders that can affect multiple endocrine glands, including the thyroid and adrenal glands, potentially leading to the symptoms described. However, they would be an unusual cause of the acute presentation described.