Thyroid
The thyroid gland sits in the neck and sets the body’s energy pace. This topic explains which thyroid changes can follow leukaemia treatment, especially radiation, and how they are checked.
01Short answer
02Simple explanation
The thyroid sets the energy pace.
The main risk is radiation.
The most common problem is hypothyroidism.
Checks: TSH, free T4, neck exam.
Treatment is a daily tablet.
03Scientific explanation
Radiation: the COG recommends a yearly TSH and free T4 test for people who had total body, craniospinal or neck radiation.
Hypothyroidism: according to MedlinePlus, signs develop slowly and can be mistaken for tiredness, feeling cold, weight gain, constipation and depression.
Nodules: thyroid nodules are more common after radiation; the ATA notes that the great majority are benign.
Central hypothyroidism: if head radiation has affected the pituitary, TSH can look normal, so free T4 is checked too (Endocrine Society 2018).
04What happens in the body?
What does the thyroid do?
Its hormones set the body’s “speed”: how much energy cells use, how fast the heart beats, how warm or cold you feel.
Which treatment affects it?
Mainly total body irradiation, craniospinal and neck radiation. In some cases transplant and targeted medicines can also affect the thyroid.
Signs of hypothyroidism
Persistent tiredness, feeling cold, weight gain, constipation, dry skin, hair loss, low mood and a slow heart rate. In children, slower growth.
How is it checked?
A blood test — TSH and free T4. The neck is examined by hand; if a nodule is suspected, an ultrasound.
Treatment
Hypothyroidism is treated with a daily levothyroxine tablet; the dose is adjusted by blood tests. Nodules are assessed by ultrasound and, if needed, a biopsy.
When to call your doctor
Worrying signs — fever, bleeding, new pain, breathlessness — should be reported to your doctor between visits too. Getting in touch early is always better than waiting.
05Thyroid follow-up
Steps of thyroid follow-up.
06Thyroid problems (simplified)
| Problem | Signs | Check and treatment |
|---|---|---|
| Hypothyroidism | Tiredness, feeling cold, weight gain | TSH, T4; levothyroxine |
| Hyperthyroidism | Palpitations, weight loss, anxiety | TSH, T4; treatment by your doctor |
| Thyroid nodule | A lump in the neck, often no symptoms | Ultrasound, biopsy if needed |
| Central hypothyroidism | Signs of hypothyroidism | Free T4 (TSH may be normal) |
* Your doctor sets the testing schedule.
07Key terms
- Thyroid
- A butterfly-shaped gland in the neck.
- TSH
- The pituitary hormone that stimulates the thyroid.
- Free T4
- The thyroid’s main hormone.
- Hypothyroidism
- An underactive thyroid.
- Hyperthyroidism
- An overactive thyroid.
- Levothyroxine
- A medicine that replaces thyroid hormone.
08Key points
- The thyroid regulates energy.
- Radiation is the main risk factor.
- Yearly TSH and T4 if at risk.
- Get neck lumps checked.
- Hypothyroidism is easy to treat.
- Take your tablet regularly.
09Frequently asked questions
I am tired — could it be my thyroid?
It could; a simple blood test checks this.
Will I need levothyroxine for life?
Often yes; it replaces the natural hormone and is safe at the right dose.
How should I take the tablet?
Usually in the morning on an empty stomach, at the same time every day; your doctor gives instructions.
Is a nodule cancer?
Most nodules are benign; ultrasound and, if needed, a biopsy will clarify.
Does this information replace medical advice?
No. This is general education; only your treating doctor can assess your situation.
10Questions for your doctor
Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.
I am tired — could it be my thyroid?
Will I need levothyroxine for life?
How should I take the tablet?
Is a nodule cancer?
Does this information replace medical advice?
12Sources
- Children's Oncology Group. Long-Term Follow-Up Guidelines for Survivors of Childhood, Adolescent and Young Adult Cancers
- National Cancer Institute (NCI). Late Effects of Treatment for Childhood Cancer (PDQ®)–Patient Version
- MedlinePlus (U.S. National Library of Medicine). Thyroid Tests
- MedlinePlus (U.S. National Library of Medicine). Hypothyroidism
- MedlinePlus (U.S. National Library of Medicine). Hyperthyroidism
- American Thyroid Association. Thyroid Nodules
- National Cancer Institute (NCI). Follow-Up Medical Care
- National Cancer Institute (NCI). Cancer Survivorship
- Cancer.Net (ASCO). Follow-Up Care After Cancer Treatment
- Leukemia & Lymphoma Society (LLS). Long-Term and Late Effects of Treatment