Differential Diagnosis
- Single most likely diagnosis
- Gestational transient thyrotoxicosis: This condition is often associated with hyperemesis gravidarum, which the patient is experiencing. The suppressed TSH level along with normal free T4 and free T3 levels, especially in the context of the first trimester (week 10), supports this diagnosis. It's a condition that typically resolves on its own as the pregnancy progresses.
- Other Likely diagnoses
- Hyperemesis gravidarum-induced thyrotoxicosis: Similar to gestational transient thyrotoxicosis, this condition is directly related to the severe nausea and vomiting (hyperemesis) experienced during pregnancy, which can lead to transient alterations in thyroid function tests.
- Graves' disease: Although less likely given the normal thyroid function tests before pregnancy, Graves' disease could present with suppressed TSH and could be exacerbated by pregnancy. However, free T4 and free T3 levels are on the higher end of normal but not definitively elevated, which might suggest a milder or early form of the disease.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Thyroid storm: Although the patient's free T4 and free T3 are within normal limits, any sign of thyrotoxicosis, especially in the context of pregnancy, warrants consideration of thyroid storm, a life-threatening condition that requires immediate medical attention.
- Molar pregnancy: This rare condition can cause elevated hCG levels, which in turn can stimulate the thyroid gland, leading to thyrotoxicosis. Given the patient's symptoms of hyperemesis and thyrotoxicosis, it's crucial to rule out a molar pregnancy.
- Rare diagnoses
- Trophoblastic disease (e.g., choriocarcinoma): Similar to molar pregnancy, other trophoblastic diseases can produce high levels of hCG, leading to thyrotoxicosis. These conditions are rare but critical to diagnose due to their potential for malignancy and severe complications.
- Thyroiditis: Although less common in the context provided, thyroiditis (inflammation of the thyroid gland) can cause transient thyrotoxicosis due to the release of pre-formed thyroid hormones into the bloodstream. It might be considered if other diagnoses are ruled out and the clinical presentation evolves.