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Thyroid Scan and Breastfeeding

Your endocrinologist can find out about your thyroid function by enquiring about your symptoms, examining you and performing blood tests. Sometimes they will want to see what the gland looks like, this is usually done with ultrasound, but occasionally it might be with CT, MRI or CT-PET scanning.

If the doctor wants to check how active the gland is, for instance to distinguish Graves' disease causing hyperthyroidism from destructive thyroiditis (de-Quervain's thyroiditis, post-partum or silent thyroiditis), understand whether a nodule or nodules are active or not, then they might need to do a nuclear medicine scan. This many involve one of a few nuclear radioisotopes that are concentrated in the thyroid, and the tiny amounts of radioactivity released can be measured using special cameras within the nuclear medicine department.

These tests are generally safe for you and for those around you, but we take special precautions when women are pregnant and/or nursing or breastfeeding babies. The radioisotope, as it goes round the body can be incorporated into the breast milk, your baby might drink it, and the radioisotope will go the baby's developing thyroid. We wish to avoid this.

If you are having a nuclear medicine thyroid scan, let the department know and they will give you specific advice, personally relevant to you, your condition, radioisotope type and dose planned, and your circumstances. The aim of guidance here is to ensure the amount of radiation that might reach the baby is insignificant.

Before the test

At least one feed should be “banked” before the test – milk should be expressed and stored in a refrigerator or freezer.

The infant should be fed naturally just before the test.

After the test

Three to four hours after the test, you should express your milk as completely as possible and discard this milk. You may feed your baby with the previously “banked” milk at this time.

Resuming normal breast feeding

The recommended delay period before you may recommence breastfeeding is dependent on the type of test carried out.

After a thyroid uptake scan, normal breastfeeding may recommence 24 hours after the test.

Milk expressed within this time should be discarded.

This is the general advice from the King's College Hospital Nuclear Medicine Department.

Every effort is made to ensure that this health and medication advice is accurate and up to date. It is for information only and supports your consultation it does not obviate the need for that consultation and should not replace a visit to your doctor or health care professional.

The written advice is general in nature and in is not specific to individual patients and Dr Philip Kelly cannot accept any liability for actions arising from its use nor can he be held responsible for the content of any pages contained in any external link.

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