A lump in your neck may be concerning
and can be particularly so when it's located in the thyroid. A thyroid lump, or
"nodule," is a growth in the thyroid gland at the front of the neck.
More often than not, thyroid nodules are not cancerous (benign). However, it is
important to evaluate properly so that they can be understood, thyroid function
can be evaluated, and, if necessary, further investigation or treatment should
be done.
Tests required for a thyroid nodule
vary based on symptoms, size, appearance, medical history, and thyroid hormone
levels. At Molecular Diagnostics and Therapy, doctors use diagnostic tests to
obtain information to help them make the best diagnosis and treatment decisions
for thyroid imbalances.
What Is a Thyroid
Nodule?
Thyroid Nodules are pockets of an
unusual growth of thyroid tissue. They can be solid, fluid-filled (cystic), or
solid and fluid-filled (cystic). Some of the nodules are found during a
physical exam, and others are "incidentally" found while imaging for
another purpose.
Several possible causes of thyroid
nodules include normal tissue growth, thyroid cysts, inflammation, or, less
commonly, endocrine gland cancer. Many do not have symptoms. The larger nodules
can cause a variety of health issues, including neck swelling, trouble
swallowing, a sensation of pressure in the neck, or voice changes. The doctor
may order one or more tests, which can help confirm the cause and help
determine whether the nodule needs to be watched or tested more for the
diagnosis.
1. Thyroid Function
Tests
One of the initial tests that are
generally pursued upon discovering a thyroid nodule is a blood test. These
tests help to see if the thyroid gland is making the right amount of hormones.
The main tests include:
Thyroid-Stimulating Hormone (TSH): Thyroid Stimulating Immunoglobulin (TSI): TSI is
another blood test that is ordered first and helps determine the function of
the thyroid. Abnormal results could be an indicator that the thyroid is not
working well and can help decide on further tests.
Free T4: This is used to determine the amount of free thyroxine, one of the
hormones made by the thyroid gland. May be suggested if the TSH is abnormal or
if symptoms indicate a thyroid hormone imbalance.
T3: A thyroid hormone (T3) may be ordered in selected cases, especially
children and young adults who have an overactive thyroid, or when other blood
tests are normal.
The tests help determine the
functioning of the thyroid, but are not used to diagnose whether a nodule is
cancer or not on their own. The thyroid hormone level can be normal even if
there's a nodule.
2. Thyroid Ultrasound
One of the most important
investigations used to assess a thyroid's lump is a thyroid Ultrasound. It is
able to create images of the thyroid region and adjacent tissues without the
presence of ionizing radiation.
They use the scan to see how big,
shaped, made of what, and have a fixed margin around the nodule, and what sorts
of features are deeper within the nodule. It can also determine if the lump is
solid, cystic, or partly solid and fluid-filled. This can tell if several
nodules are present or if there are enlarged lymph nodes in the neck.
Some features on ultrasound could
suggest a greater risk of cancer or decrease the risk. Recognised risk
assessment score systems like the American College of Radiology Thyroid Imaging
Reporting and Data System (ACR TI-RADS) can be used by doctors to categorise
nodules and inform further evaluation or biopsy procedures.
Not all thyroid nodules can be used to
take a tissue sample from them. This is based on the ultrasound characteristics
of the nodules, their size, the clinical history of the nodules, and the risk
assessment method of the physician who treats them.
3. Fine-Needle
Aspiration Cytology (FNAC)
Fine-Needle Aspiration Cytology (FNA)
is sometimes suggested when a thyroid nodule has suspicious ultrasound
characteristics or if it is of an appropriate size.
A very thin needle is passed through
the nodule for a small sample of cells. A needle is guided by ultrasound in
order to position it accurately. The sample is collected and examined under a
microscope for cellular changes.
FNAC can help to classify the nodule as
benign, suspicious, malignant, or indeterminate. In some cases, however, some
samples may not be sufficient or may not be conclusive; further evaluation may
be needed.
The intention of FNAC is not to assess
the risk of lumps, but to provide an overall risk assessment. If the nodule is
of low risk and not suitable for biopsy, your provider may suggest follow-up
ultrasound scans every 6 months or so.
4. Thyroid Nuclear
Medicine Scan
In certain individuals, a thyroid
nuclear medicine scan may also be recommended, such as when the TSH is low and
there is a suspicion of an overactive thyroid nodule. During this exam, a low
dose of radioactive iodine is administered, which is absorbed by the thyroid
gland. The tracer is then imaged in a special camera in the human body, which
shows how the tracer is distributed across the gland.
The scan can help determine if the
nodule is more active or if the activity is more concentrated within the area
of the nodule. These kinds of nodules may be referred to as hyperfunctioning
nodules or “hot nodules”. Nodules that do not absorb a tracer are called
hypofunctioning or “cold” nodules.
A nuclear scan is not needed for
every thyroid lump, and a cold nodule is not necessarily cancer. The
ultrasound, thyroid function, and clinical examination are still important
components of the decision-making process regarding the need for a biopsy.
Dr. Nikunj Jain, Co-Founder & Head
of Nuclear Medicine at Molecular Diagnostics and Therapy, has experience in
thyroid-related investigations and nuclear medicine imaging. A thyroid scan may
or may not apply to a particular patient with clinical features and should be
decided by their treating physician.
Conclusion
If a thyroid lump or nodule is
discovered, further blood tests are ordered to check the function of the
thyroid; a thyroid ultrasound test and, in selected patients, a nuclear
medicine scan or further imaging tests are recommended. The information these
investigations can offer varies by nodule and will assist the doctor in
assessing the function of that nodule, its characteristics, and indications for
monitoring, biopsy, or treatment.
Dr. Nikunj Jain at Molecular Diagnostics and Therapy is a Co-Founder and Head of the Department of Nuclear Medicine with experience in nuclear medicine and thyroid-based diagnostic assessment. The testing pathway should always be set according to the symptoms, examination, laboratory data, and imaging results and should be individualised