The diagnostic and follow-up process for hypothyroidism, hyperthyroidism, goiter, and thyroid nodules using blood tests and ultrasound.
Indication
- Symptoms suggesting thyroid disease such as fatigue, weight changes, palpitations, heat/cold intolerance, hair loss
- Palpable swelling in the neck, goiter, or thyroid nodule detected on imaging
- Suspicion of autoimmune thyroid disease such as Hashimoto thyroiditis or Graves disease
- Follow-up of subclinical hypothyroidism/hyperthyroidism (TSH abnormal, T3-T4 normal)
- Thyroid function screening before/during pregnancy
- Regular monitoring of patients previously diagnosed with thyroid disease
- Follow-up in individuals with a history of neck radiotherapy or thyroid surgery
Preparation
- Generally no special preparation is required; fasting is not mandatory, but blood may be drawn fasting in the morning if recommended by the physician
- Patients using levothyroxine (Synthroid, Tefor, etc.) generally do not take the medication before the blood test; it is taken after the result
- Biotin-containing supplements (hair, nail vitamins) may affect some laboratory tests, so discontinuation 3-7 days in advance is recommended
- Previous thyroid tests and a list of medications used should be brought
- Jewelry and metal accessories are removed for the neck ultrasound
How it's performed
- A detailed history is taken and a neck examination is performed (thyroid gland size, nodule, lymph node)
- TSH (reference range generally 0.4-4.0 mIU/L), free T4 (fT4), and free T3 (fT3) levels are measured by blood test
- Anti-TPO and anti-Tg antibodies in suspicion of autoimmune thyroiditis, TRAb (TSH receptor antibody) in suspicion of Graves
- Thyroid ultrasonography is used to assess gland size, echogenicity, and nodule presence; if a nodule is detected, risk is classified according to the TI-RADS system
- When needed to differentiate the cause of hyperthyroidism, thyroid scintigraphy (radioactive iodine uptake) may be performed
- Results are interpreted considering the patient's age, pregnancy status, and accompanying conditions
Post-procedure
- In subclinical disorders, follow-up with TSH measurement is performed every 6-12 weeks
- In patients started on levothyroxine, TSH is checked after 4-8 weeks for dose adjustment; once stabilized, it is checked 1-2 times per year
- In patients with thyroid nodules, ultrasound follow-up is planned at 6-12 month intervals; intervals lengthen if risk is low
- In those using antithyroid medications (methimazole, propylthiouracil), liver function and complete blood count are regularly monitored
- Lifestyle recommendations: adequate iodine intake, smoking cessation, balanced nutrition
Risks
- The testing process itself is low-risk; mild bruising or dizziness may occur during blood draw
- Incorrect timing (e.g., biotin effect) may cause misleading results
- If treatment is started, excess levothyroxine dose may cause palpitations and decreased bone density; insufficient dose may cause fatigue and weight gain
- Antithyroid medications may rarely cause serious liver toxicity or low white blood cell count (agranulocytosis)
- Missed or delayed diagnosis may increase the risk of pregnancy complications or cardiac arrhythmias
FAQ
My TSH is high, what does it mean?
Elevated TSH generally suggests hypothyroidism, in which the thyroid gland cannot produce sufficient hormone. Mild elevations may represent subclinical hypothyroidism; the decision on whether treatment is needed is made by evaluating it together with free T4 and antibodies.
Is a thyroid nodule cancer?
The vast majority of thyroid nodules (about 90-95%) are benign. Risk assessment is based on ultrasound features (TI-RADS), nodule size, patient age, and family history. Fine-needle biopsy may be recommended for suspicious-looking nodules.
Will I need to take thyroid medication for life?
In permanent hypothyroidism such as Hashimoto, levothyroxine generally continues for life. In transient thyroiditis (postpartum, viral) and similar causes, the medication may be discontinued after several months to years. Your physician makes the decision based on your test results.
Why is thyroid testing important during pregnancy?
During pregnancy, thyroid hormones are critical for the baby's brain development. Untreated hypothyroidism can lead to miscarriage, premature birth, and developmental issues in the baby. Therefore, TSH screening is recommended before pregnancy and in the early period.
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