case studies growth [026] Flashcards
- What is your diagnosis of his clinical features?
Acromegaly, which is excess secretion of growth hormone in the adult. Acromegaly can present in a huge array of signs and symptoms. A list of the signs and symptoms of acromegaly is given below:
The Head • Large tongue • Interdental separation - separation of teeth due to alveolar bone growth • Prominent supraorbital ridge • Prognathism - growth of the mandible leading to a jutting jaw • Visual field defects • Goitre - due to generalised visceral enlargement • Headaches The Body • Galactorrhoea • Hirsuties • Heart failure • Generalised organomegaly increase in size of heart, kidney, spleen, liver etc. • Hypertension • Impotence • Amenorrhoea The Limbs • Increase in size of hands and feet • Tight-fitting rings • Carpal tunnel syndrome • Proximal myopathy • Arthropathy • Oedema The most common presenting complaint is that of a change in appearance. This is can be seen by studying old photographs. Acromegaly usually presents as a subtle disease with the clinical features developing over many years. Some patients may present with galactorrhoea as in some tumours, both somatotrophin and prolactin are secreted. Approximately a quarter of acromegaly patients have an impaired glucose tolerance due to the increased gluconeogenesis produced by the growth hormone.
- What do the plasma levels tell you?
A random high growth hormone is of no diagnostic value due to the large physiological variations in normal growth hormone levels. An important test in the diagnosis of acromegaly is the glucose tolerance test. The patient is given a 75g glucose meal, and blood tests are taken at half-hourly intervals. In a normal patient the growth hormone levels will be suppressed, but in the acromegaly patient the growth hormone levels are unsuppressable.
Another unique test that can be used in the diagnosis of acromegaly is by the administration of TRH. This is a unique test as only in acromegaly will there be a doubling of the blood levels of growth hormone.
Another test that is routinely done is the blood level of the somatomedins (IGF-1), which will almost always be raised in acromegaly.
Imaging is obviously a very important part of the diagnosis. A routine plain radiograph of the skull will show an enlarged pituitary fossa in approximately 70% of patients with acromegaly. The best way to identify the tumour is by using a CT scan or an MRI scan.
- How is this endocrine condition treated?
Imaging is obviously a very important part of the diagnosis. A routine plain radiograph of the skull will show an enlarged pituitary fossa in approximately 70% of patients with acromegaly. The best way to identify the tumour is by using a CT scan or an MRI scan.
Untreated acromegaly is associated with a very high morbidity. The aim of therapy is to achieve a mean growth hormone level of less than 5mU/L, which is the level that has been associated with a decrease in mortality.
The treatment options that are available are:
-surgery
-pharmacological
- radiotherapy
-Pharmacological the main two types of drugs available for the treatment of acromegaly are the dopamine agonists and the somatostatin analogues.
Dopamine agonists alone can be given to patients to try to shrink tumours prior to surgery and also to control their symptoms.
Dopamine agonists are probably most successful at treating mixed growth hormone and prolactin secreting tumours. The dopamine agonists that are used are bromocriptine (10- 60mg/day) or cabergoline (0.5mg/day). When these drugs are used, they should be started slowly as they are associated with unpleasant sideeffects such as nausea and vomiting. The dopamine agonists have been largely replaced by the somatostatin analogues in recent years.
Octreotide is a synthetic analogue of somatostatin and is now being used to suppress growth hormone levels. It is given by subcutaneous injections (50- 200μg 8-hourly) but a long-acting preparation is now available. The somatostatin analogues are generally well tolerated but they have been associated with an increased incidence of gallstones.
Although these pharmacological interventions do seem to induce some tumour shrinkage, the treatment of choice for a tumour that is anatomically causing symptoms is surgery.
-Surgery The first-line therapy for acromegaly is surgery. Trans-sphenoidal surgery is generally agreed to be the most appropriate therapy for small intrasellar tumours of less than 1cm in diameter. This type of surgery for microadenomas seems to achieve clinical remission in approximately 60% of patients. The details of this type of surgery are found in the surgery section.
As the size of the tumour increases the percentage of patients that achieve complete clinical remission decreases. In cases when there seems to be incomplete tumour removal, radiotherapy is usually considered.
-Radiotherapy Radiotherapy is normally used in post-surgical cases where growth hormone levels have failed to normalise. The radiotherapy treatment is often combined with drug treatment for more beneficial results. The radiotherapy is usually performed over a 4-6 week period using conventional external radiation (maximum dose 4500 rad (cGy)). The radiation is given through multiple fields to reduce the risk of damage to the parasellar structures.
