Diagnosis of parathyroid cancer

Diagnosis is the process of finding out the cause of a health problem. Diagnosing cancer often means first ruling out other health conditions that share similar symptoms with cancer. It can be a very worrying time for you and your loved ones. Sometimes this process is quick. Sometimes it can feel long and frustrating. But it’s important for doctors to get all the information they need before making a diagnosis of cancer.

It can be very challenging to diagnose parathyroid cancer because a parathyroid adenoma (which is not cancer) and parathyroid cancer look very similar. Tests and scans may show that there is a tumour in one of the parathyroid glands, but it’s usually necessary to remove the tumour and examine it under a microscope to determine whether it’s cancer.

The following tests are used in the process of diagnosing parathyroid cancer. Your doctor may also order other tests to check your general health and to help plan your treatment.

Your health history is a record of your symptoms and risks and all the medical events and problems you have had in the past. Your doctor will ask questions about your history of:

• symptoms that suggest hyperparathyroidism (overactive parathyroid glands), hypercalcemia (too much calcium in the blood) or parathyroid cancer
• inherited conditions such as multiple endocrine neoplasia (MEN) and hyperparathyroidism–jaw tumour syndrome (HPT-JT)
• receiving radiation therapy to the head and neck

Your doctor may also ask about a family history of:

• parathyroid tumours and parathyroid cancer
• risks for parathyroid cancer
• other cancers

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

• feel the neck for any lumps
• check your blood pressure

Find out more about a physical exam.

Blood chemistry tests measure certain chemicals in the blood. They show how well certain organs are working and can help find problems. Blood chemistry tests used to diagnose hyperparathyroidism and help diagnose parathyroid cancer include the following.

Calcium levels are measured to check for too much calcium in the blood (hypercalcemia). If your calcium level is greater than 3 mmol/L, your doctor may suspect a tumour in one of the parathyroid glands.

Parathyroid hormone (PTH) levels are measured to check for too much PTH. If your PTH level is very high (3 to 10 times higher than normal), your doctor may suspect a tumour in one of the parathyroid glands.

Find out more about blood chemistry tests.

An ultrasound uses high-frequency sound waves to make images of parts of the body. It may be used to look for a parathyroid tumour or to see if the parathyroid glands are enlarged (parathyroid hyperplasia).

Find out more about an ultrasound.

A parathyroid scan is a nuclear medicine imaging test that uses a radioactive substance and a special camera (called a gamma camera) to take pictures of the parathyroid glands. It is used to check for hyperparathyroidism and parathyroid tumours before surgery. It may also be called a sestamibi scan or a MIBI scan.

The radioactive substance (called technetium-99m sestamibi) is injected into a vein in the arm and travels throughout the body. It is absorbed only by overactive parathyroid glands. After about 10 minutes, a gamma camera is used to take pictures of the neck and chest. Radioactive areas will show up brightly in the pictures. More pictures are taken a few hours later.

A parathyroid scan is often done with single photon emission computed tomography (SPECT). The camera moves around the neck to make 3D images.

A computed tomography (CT) scan uses special x-ray equipment to make 3D and cross-sectional images of organs, tissues, bones and blood vessels inside the body. A computer turns the images into detailed pictures.

A CT scan may be used to find out more about a tumour before surgery. It may also be used to check if parathyroid cancer has spread to other parts of the body.

Find out more about a CT scan.

Surgery is a medical procedure to examine, remove or repair tissue. A definite diagnosis of parathyroid cancer is usually only possible after surgery to remove the tumour along with one or more parathyroid glands (called a parathyroidectomy). Surgery is needed to diagnose cancer because it's often hard to tell the difference between parathyroid cancer and a parathyroid adenoma based on blood tests and imaging tests.

The tissue that is removed is sent to a lab where a pathologist makes a diagnosis after examining the tissue under a microscope.

Magnetic resonance imaging (MRI) uses powerful magnetic forces and radiofrequency waves to make cross-sectional images of organs, tissues, bones and blood vessels. A computer turns the images into 3D pictures.

An MRI may be used to check if parathyroid cancer has spread to other parts of the body.

Find out more about an MRI.

A positron emission tomography (PET) scan uses radioactive materials called radiopharmaceuticals to look for changes in the metabolic activity of body tissues. A computer analyzes the radioactive patterns and makes 3D colour images of the area being scanned.

A PET scan may be used to check if parathyroid cancer has spread to other parts of the body.

Find out more about PET scans.

Find out more about a diagnosis. To make the decisions that are right for you, ask your healthcare team questions about diagnosis.