thyroid hormone as appropriate. When thyroid hormone
levels are low, the TSH rises responsively and
vice versa; thus, measuring a TSH level allows differentiation
between functional and nonfunctional nodules.
This is an important characteristic, because hyperfunctioning
nodules are rarely malignant. However, if a
TSH is subnormal, indicating a hyperactive gland, a
nuclear medicine imaging study (thyroid uptake and
scan) should be performed, to document whether the
nodule itself is hyperfunctioning (hot), isofunctioning
(warm), or nonfunctioning (cold) compared with the
surrounding thyroid tissue. If the nodule is hot or warm,
no cytologic evaluation is necessary; however, if the
patient is symptomatic, additional evaluation is required
to rule out other causes, such as Graves’ disease,
and to provide adequate treatment.
Nonfunctioning nodules will require the use of fineneedle
aspiration (FNA) for cytologic evaluation. However,
if the TSH is normal or elevated, even within the
upper limits of normal, a FNA is recommended, because
the rate of malignancy is higher with nonfunctioning
nodules and glands affected by Hashimoto’s thyroiditis, a
common autoimmune hypothyroid disease.5
Along with serum TSH, a diagnostic neck ultrasound
should be performed on all suspected nodules to confirm
the existence of a nodule and to check for any suspicious
features.5
However, no single ultrasound feature and no
combination of ultrasound features is sensitive enough or
specific enough to identify malignancy by themselves.
Some ultrasound features have greater correlation with