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Parathyroid cancer

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Diagnosing parathyroid cancer

Diagnosis is the process of finding the cause of a health problem. The process of diagnosis may seem long and frustrating, but it is important for the doctor to rule out other reasons for a health problem before making a cancer diagnosis. Diagnostic tests for parathyroid cancer are usually done when:

  • the symptoms of parathyroid cancer are present
  • the doctor suspects parathyroid cancer after talking with a person about their health and completing a physical examination

Many of the same tests used to initially diagnose cancer are used to determine the stage (how far the cancer has progressed). Your doctor may also order other tests to check your general health and to help plan your treatment. Tests may include the following.

Note: A needle biopsy is not done if parathyroid cancer is suspected because there is a risk that this procedure may spread the cancer (tumour seeding).

Medical history and physical examination

The medical history is a record of present symptoms, risk factors and all the medical events and problems a person has had in the past. The medical history of a person’s family may also help the doctor to diagnose parathyroid cancer.

In taking a medical history, the doctor will ask questions about:

  • a personal history of genetic diseases that are risk factors for parathyroid cancer, such as:
    • multiple endocrine neoplasia (MEN) type I
    • hyperparathyroidism-jaw tumour (HPT-JT) syndrome
  • previous radiation therapy to the head or neck
  • signs and symptoms that may suggest parathyroid cancer

A physical examination allows the doctor to look for any signs of parathyroid cancer. During a physical examination, the doctor may:

  • feel the neck for lumps
  • check for general signs of health

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Blood chemistry tests

Blood chemistry tests measure certain chemicals in the blood. They show how well certain organs are functioning and can also be used to detect abnormalities. They are used to diagnose parathyroid cancer.

  • Blood calcium levels greater than 14 mg/dL suggest cancer.
    • Blood calcium levels that are higher than normal but less than 14 mg/dL suggest a benign parathyroid tumour or condition.
  • A parathyroid hormone (PTH) level greater than twice the normal level suggests parathyroid cancer.

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Sestamibi scan

A sestamibi scan is the most common imaging tool used to assess the parathyroid glands. It is the most sensitive test for identifying parathyroid tumours. A sestamibi scan uses radioactive materials (radiopharmaceuticals) to detect changes in the metabolic activity of the parathyroid glands. A computer analyzes the radioactive patterns and makes images of the area being scanned.

A small amount of radioactive material, usually technetium-99m sestamibi, is injected into a vein and travels throughout the body. The radioactive material is readily taken up by the overactive parathyroid gland. A special camera, sensitive to radioactivity, gives an accurate picture of the gland.

A sestamibi scan is used to:

  • identify the size and location of the parathyroid glands
  • show how well the parathyroid glands are working

A sestamibi scan may be done with single photon emission computed tomography (SPECT), which adds 3-dimensional imaging. This is called a sestamibi/SPECT scan.

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Ultrasound

Ultrasound uses high-frequency sound waves to make images of structures in the body. It is used to:

  • assess the neck and surrounding lymph nodes
  • identify parathyroid tumours that have invaded nearby tissues

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Computed tomography (CT) scan

A CT scan uses special x-ray equipment to make 3-dimensional and cross-sectional images of organs, tissues, bones and blood vessels inside the body. A computer turns the images into detailed pictures. It is used to:

  • assess the central part of the chest cavity (the mediastinum)
    • Sometimes there are parathyroid glands in the mediastinum.
  • identify distant metastases

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Magnetic resonance imaging (MRI)

MRI uses powerful magnetic forces and radio-frequency waves to make cross-sectional images of organs, tissues, bones and blood vessels. A computer turns the images into 3-dimensional pictures. It is used to:

  • assess the central part of the chest cavity (the mediastinum)
  • identify distant metastases

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Venous sampling

If all the imaging tests do not help doctors identify which parathyroid gland is overactive, a blood sample is taken from the veins near each parathyroid gland. The blood is tested to measure the amount of parathyroid hormone being secreted. An elevated level may indicate which gland is overactive based on the location of the vein from where the sample was taken.

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X-ray

An x-ray uses small doses of radiation to make an image of the body’s structures on film. It is used to:

  • check the lungs or bones for metastases

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Positron emission tomography (PET) scan

A PET scan uses radioactive materials (radiopharmaceuticals) to detect changes in the metabolic activity of body tissues. A computer analyzes the radioactive patterns and makes 3-dimensional colour images of the area being scanned. It is used to:

  • identify recurrent disease

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See a list of questions to ask your doctor about diagnostic tests.

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