Let's go on to another case.
A 55 year old woman was diagnosed
with hyperthyroidism one week ago.
She also has a palpable right thyroid
nodule which was found on clinical exam.
Her TSH was low and her
free T4 was elevated.
She has no weight loss, no history of prior
malignancy nor family history of any cancer.
What is the best next step
in managing this patient?
So clinically based on the information that we
have, she has been diagnosed with hyperthyroidism
and she also has a palpable
right thyroid nodule.
This points to the diagnosis
of a toxic adenoma.
The next step in the management would be thyroid
scintigraphy scan or radioactive iodine uptake
which in this case would show a single
area of increased uptake of iodine
in the area of the toxic adenoma.
Thyroid scintigraphy scanning
is a nuclear medicine procedure
that produces a visual display
of functional thyroid tissue
based on the selective uptake of radioactive
iodine nucleides by the thyroid tissue.
If you look at this image, you see areas
on the gray background of intense uptake
which are much, much darker
representing large black dots.
These represent toxic adenomas within the
thyroid gland and are very discreet.
Activating mutations in
the TSH receptor gene
stimulate the production of thyroid
hormone in a toxic nodule,
usually referred to as an adenoma.
or in multiple hyperfunctioning nodules
in a toxic multinodular goiter.
On exam, the nodule may be
palpable or diffusely enlarged
where it's called a goiter or
it may have a nodular contour.
There is a very low risk of autonomous
nodules from malignant transformation.
Usually in the range of less than 1%.
The diagnosis is usually made
by thyroid scintigraphy.
In the case of an autonomous toxic nodule, this
is described as "hot" or very dark on imaging.
You should always correlate any nodules found on
scintigraphy scanning with an associated ultrasound.
Any additional nodules that are found on ultrasound
that are not seen on scintigraphy scanning
may require further investigation
by doing a fine needle aspiration.
Radioactive iodine ablation
emits gamma and beta radiation.
The camera detecting this on a nuclear testing
will detect the uptake of the thyroid hormone
and generate a picture for diagnosis.
Indications for surgery in patients with
toxic adenomas include very large goiters
with compression symptoms on the underlying
tissue where there is concern for malignancy.
TSH secreting pituitary
adenomas are extremely rare.
These are causes of secondary
or central hyperthyroidism.
Serum TSH is detectable or normal
with elevated T4 and/or T3 levels.
A pituitary MRI in these cases will
usually demonstrate an adenoma.
The treatment for these conditions
is removal of the pituitary tumor
as thyroid-targeted therapy
is invariably ineffective.