Common symptoms
- Fatigue during dose adjustment after surgery
- Neck stiffness, scar tightness, and altered swallowing
- Voice changes or hoarseness
- Tingling in fingers, toes, or around the mouth from low calcium
- Palpitations, tremor, or sleep disturbance if the dose is too high
- Cold intolerance and brain fog if the dose is too low
Which labs matter
| Test | What it shows |
|---|---|
| TSH | Kept at a target set by recurrence risk, often below the standard reference range. |
| Free T4 | Confirms replacement is adequate without excessive over-replacement. |
| Thyroglobulin (Tg) and anti-Tg antibodies | Tumour marker after total thyroidectomy; antibodies must be measured because they interfere with the Tg result. |
| Calcium and PTH | Monitored after surgery because the parathyroid glands can be affected. |
| Vitamin D | Supports calcium management, particularly with parathyroid injury. |
| Neck ultrasound | Surveillance for structural recurrence in the thyroid bed and lymph nodes. |
Why the TSH target is different
In differentiated thyroid cancer, TSH can stimulate any remaining cancer cells, so guidelines set individualised TSH targets based on recurrence risk and response to treatment — sometimes suppressed below the ordinary reference range, sometimes in the low-normal range for low-risk patients whose disease has responded well.
Targets are reassessed over time. Because suppression carries risks for bone density and heart rhythm, the aim is the least suppression required for your risk category, which changes as surveillance results accumulate.
Getting replacement dosing right
Hitting a narrow TSH target depends on consistent absorption. Levothyroxine should be taken on an empty stomach with water, 30–60 minutes before food and coffee, and kept about four hours away from calcium, iron, magnesium, and multivitamins — which is a particular challenge for patients taking calcium supplements after parathyroid injury.
If you take both, spacing them across the day and keeping the same routine every day is what makes results comparable between blood tests.
Calcium and parathyroid issues after surgery
The parathyroid glands sit next to the thyroid and can be bruised or removed during surgery, which lowers blood calcium. Tingling around the mouth or in fingers and toes, and muscle cramps or twitching, are the classic early signs and should be reported promptly.
Some patients need calcium and active vitamin D temporarily; a minority need it long term. Tracking symptoms alongside calcium results helps distinguish a genuine drop from anxiety-related sensations, which are common after surgery.
What to track
Cancer follow-up spans years and multiple clinicians. A single record of results and symptoms is often the only continuous thread, and it is the thing that makes surveillance appointments efficient.
- TSH, Free T4, thyroglobulin, and anti-Tg antibodies with dates
- Calcium, PTH, and vitamin D results
- Levothyroxine dose changes and the reason for each
- Medication timing, including gaps from calcium and iron
- Symptoms of over- and under-replacement: palpitations, tremor, fatigue, cold intolerance
- Ultrasound and imaging dates with findings