Differential Diagnosis for Thyroid Conditions
The following differential diagnosis is based on laboratory studies to differentiate between Graves' disease, Hashimoto thyroiditis, postpartum thyroiditis, and subacute thyroiditis.
Single Most Likely Diagnosis
- Graves' disease: This is often the first consideration in patients presenting with hyperthyroidism, especially if they have a diffuse goiter and exophthalmos. Laboratory studies typically show elevated free T4 and T3, low TSH, and positive TSH receptor antibodies.
- Hashimoto thyroiditis: This is a common cause of hypothyroidism, especially in women. Laboratory studies often reveal elevated TSH, low free T4, and positive anti-thyroid peroxidase (TPO) antibodies.
Other Likely Diagnoses
- Postpartum thyroiditis: This condition occurs in some women after childbirth and can present with either hyperthyroidism or hypothyroidism. Laboratory studies may show elevated or decreased TSH and free T4 levels, and positive anti-TPO antibodies.
- Subacute thyroiditis: This condition is characterized by thyroid inflammation, often following a viral infection. Laboratory studies may show elevated TSH, low free T4, and elevated erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP).
Do Not Miss Diagnoses
- Thyrotoxic crisis: Although rare, this is a life-threatening condition that requires immediate attention. Laboratory studies may show very high levels of free T4 and T3, and low TSH.
- Thyroid storm: Similar to thyrotoxic crisis, this is a severe and life-threatening exacerbation of hyperthyroidism. Laboratory studies are similar to those in thyrotoxic crisis.
Rare Diagnoses
- Riedel's thyroiditis: A rare form of chronic thyroiditis characterized by a hard, fibrotic thyroid gland. Laboratory studies may show elevated TSH and low free T4, but the diagnosis is often made based on clinical and radiological findings.
- Silent thyroiditis: A rare condition characterized by transient hyperthyroidism or hypothyroidism without significant thyroid inflammation. Laboratory studies may show elevated or decreased TSH and free T4 levels, but the diagnosis is often made based on clinical presentation and response to treatment.
- Amiodarone-induced thyroiditis: A rare condition caused by the use of the medication amiodarone, which can lead to either hyperthyroidism or hypothyroidism. Laboratory studies may show elevated or decreased TSH and free T4 levels, and the diagnosis is often made based on the patient's medication history.