Acromegaly

What is it?

Acromegaly is the name given to a condition caused by the body producing too much growth hormone (GH). The excess GH usually (about 95% of cases) comes from a non-cancerous tumour in the pituitary gland. It is a fairly rare disease with about 50 cases per million in the population. The increased amount of GH also leads to increased formation of another hormone, insulin-like growth factor (IGF-1).

These two hormones have a number of effects on the body most being due to an increase in size of tissue or organs.

The other 5% of cases of excess growth hormone and acromegaly are caused by growth hormone-releasing hormone (GHRH) or GH being produced in tumours elsewhere in the body.

Signs and symptoms

In most cases the symptoms of acromegaly develop very slowly and signs may not be noticed for some time (several months).

The external signs include:

  • Enlarged hands, making difficult or impossible to remove rings on fingers
  • Enlarged feet which can mean an increase in shoe size
  • Thickening of the lips
  • Enlarged, thickened nose
  • Increased size of the tongue
  • Increase in size of the bony ridges over the eyes
  • Changes in the jaw, making it difficult to bite normally
  • Deepening of the voice

Other changes include:

  • Increases in size of the heart, thyroid, liver and spleen
  • Carpal tunnel syndrome. This is caused by an increase in the tissues of the wrist that press on the nerves and cause tingling and pins and needles in the fingers.
  • Bone and joint pain

Although patients may go to the doctor because of changes to face, hands or feet, often it is other symptoms, such as menstrual disturbance in women, headaches and carpal tunnel syndrome, which lead the patient to see their doctor.

Headaches are caused by the tumour in the pituitary gland increasing in size and pressing on the base of the brain.

There is a threefold increase in the risk of death in patients with acromegaly. Death may result from heart disease, respiratory disorders, diabetes and malignancy. Therefore effective treatment is essential.

Tests

IGF-1 measured in the blood is the test of choice and will be raised in a patient with acromegaly.

An MRI scan of the pituitary will be carried out in patients with symptoms of acromegaly and a raised IGF-1. This is to identify thepresence of a tumour in the pituitary and to assess its size.

Treatment

Surgical removal of the tumour is usual. This can often be achived by an operation through the sinus passages behind the nose. The smaller the tumour the easier it is for the surgeon to remove the whole tumour. It is more difficult to remove large tumours totally and some tissue may be left.

Total removal of the tumour will result in GH and IGF-1 levels in the blood falling quickly and symptoms will start to diminish. IGF-1 will be measured after surgery to assess whether all the tumour was removed.

Sometimes the cells of the pituitary producing other hormones, such as Adrenocorticotrophic hormones (ACTH), thyroid stimulating hormone (TSH), luteinizing hormone (LH) and follicle stimulating hormone (FSH), are affected or removed and secretion of these hormones is lost. The patient will then be required to take hormone supplements such as thyroxine and cortisol depending on which hormones are lost.

In difficult cases or where tumour removal is incomplete further treatment may be used. These include radiation and injections of substances like octreotide which blocks the production of GH or pegvisomant that blocks the action of GH. These latter substances are slow acting and symptoms diminish gradually over the next couple of years.