Multinodular goitre

Nodular thyroid swelling which may be associated with hyperthyroidism, and is not auto-immune in origin. The diagnosis is usually made clinically, though an ultrasound scan and thyroid function testing are often performed as part of the assessment.

Base investigations - all patients

Full blood count

This is a useful indicator of general health and underlying disease.

Urea and electrolytes

This is a useful indicator of underlying disease.

Liver function test

Liver function should be tested at baseline before starting medical treatments.

Bone profile

Hypercalcaemia may occur with thyrotoxicosis, or with malignancy.

Free thyroxine

TSH and free Thyroxine should be tested together in patients with a multinodular goitre. Elevated thyroxine with suppressed TSH confirms this to be a toxic mulitnodular goitre which always requires treatment, usually with radioactive iodine or anti-thyroid drugs.

A low TSH repeated on more than one occasion with a normal thyroxine levels implies autonomous function of the goitre. The decision to treat in such cases is more complex.

Thyroid stimulating hormone

A patient with a normal TSH, with no 'red flag' symptoms and who is asymptomatic may not require any treatment for a multinodular goitre.

A low TSH generally implies hyperthyroidism or autonomous function from within a multinodular goitre. An isolated low TSH should be repeated after three months before informing long term treatment, as this may normalise.

Electrocardiogram

ECG should be performed in all patients at baseline to document and confirm any arrhythmias or other changes.

Thyroid auto-antibody screen

Thyroid peroxidise (TPO) antibodies may be used as an initial screen, if there is a suspicion of auto-immune thyroid disease despite the nodular feeling gland.

Free liothyronine

Free liothyronine levels are not usually necessary for the assessment and treatment of thyrotoxicosis, though they may be useful if the TSH is suppressed and thyroxine level normal. The pattern of an elevated liothyronine, suppressed TSH, and normal thyroxine is known as 'T3 toxicosis', and is often seen with nodular thyroid disease.

Thyroid ultrasound scan

Ultrasound scan is essential in the assessment of palpable solitary thyroid nodules and to guide how and whether to perform fine needle aspiration.

Ultrasound may also be helpful where there is a suspicion of a distinct or suspicious nodule within a multinodular goitre, to define the anatomy of the goitre prior to surgery in some cases, or where the aetiology of thyroid dysfunction is unclear, for example between nodular goitre and Graves' disease in a toxic patient.

Further investigations - selected cases only

Bone densitometry

Bone mineral density should be assessed where there is clinical suspicion of osteoporosis, for example in some older patients with biochemical thyrotoxicosis.

Vitamin D levels

In patients with known or suspected osteoporosis, serum vitamin D levels will guide whether routine calcium and vitamin D supplementation is enough, or whether specific high dose vitamin D replacement is required.

Thyroid radionucleide uptake scan

This is useful in patients with acute thyrotoxicosis of uncertain aetiology. A multinodular goitre will typically have patchy uptake throughout the gland, whereas a single toxic nodule will take up iodine intensely in that part of the gland only. In Graves' disease, the whole gland will have increased uptake and, in thyroiditis, the gland will not take up any iodine at all.

Ultrasound guided fine needle aspiration

Fine needle aspiration should be performed in all solitary or suspicious nodules. Ultrasound scan improves the safety of this procedure and increases the yield by allowing the operator to target specific areas within a nodule. Aspiration of cystic contents may also be performed during sampling.

Ultrasound scanning may also identify some patients in whom needle biopsy is not necessary.

Parathyroid hormone

If serum calcium is elevated it is useful to check PTH to determine the cause. Low PTH may be seen when the thyrotoxicosis itself is the cause of hypercalcaemia, but should also raise the possibility of malignancy.

Elevated PTH implies co-incidental hyperparathyroidism, though multiple endocrine neoplasia type 2 may present with a thyroid mass due to medullary cancer as well as hyperparathyroidism.

Calcitonin

This should be tested if medullary cell thyroid cancer rather than a multinodular goitre is suspected.

Thyroglobulin

This should only be assessed in patients with documented thyroid cancer, and after thyroidectomy and radioactive iodine ablation. This will then guide future monitoring and treatment. This test is not appropriate in patients with a thyroid still present, and is not a screen for thyroid cancer.

Chest radiograph with thoracic inlet view

This is useful if tracheal deviation is suspected clinically.

CT scan of the neck and chest

This is useful to define the lower extent of a retrosternal goitre, and to assess the extent of suspected tracheal compression.

Iodine containing contrast material should not be used in patients with thyroid abnormalities as it may provoke hyperthyroidism.

Pulmonary function testing with flow volume loops

This may be useful in some cases of suspected tracheal compression where surgery or radiotherapy are under consideration.

Laryngoscopic examination of the vocal cords

This should be performed by an experienced surgeon in all patients being considered for thyroid surgery.