Definition: Cushing syndrome is a hormonal disorder and it describes the signs and symptoms associated with prolonged exposure to inappropriately high levels of the hormone cortisol. Cushing syndrome is also known as Hypercortisolism.
1. Use Of Glucocorticosteroid Medicines: The most common cause of Cushing syndrome is the excessive use of corticosteroid medicine. Prednisone, dexamethasone and Prednisolone are the examples of these medicines. The glucocorticosteroid given externally mimic the actions of the body,s normal hormone cortisol. These drugs are mainly used in the treatment of asthma, skin allergies, inflammatory diseases, etc.
2. Excess Production of the hormone Cortisol In The Body: The other cause is the excessive production of the hormone cortisol from the body. This hormone is normally produced from the adrenal glands in response to ACTH (adrenocorticotropic hormone) from the Pituitary gland. This hormone in turn is controlled by CRH (Corticotropic releasing hormone) from the hypothalamus. Some of the causes for excess production of cortisol in the body include:
- A pituitary gland tumor that release too much ACTH leading to excess stimulation of adrenal glands to produce cortisol.
- Tumors of the adrenal gland that produce excess cortisol.
- Tumors elsewhere in the body that may produce ACTH or CRH.
Clearing Some Confusing Terminologies:
1. Cushing Disease: refers to the pituitary dependent cause of cushing syndrome, that is when the syndrome is caused by the excess production of ACTH from the pituitary gland.
2. Cushing Triad: A condition unrelated to cushing syndrome that is caused by an increased intracranial pressure.
Clinical Features Of Cushing Syndrome:
A full blown case of Cushing syndrome presents with the following signs and symptoms:
- Rounded moon like face
- Weigh gain
- A fat pad in the upper back.
- Thin arms and legs.
- Central obesity ( A lemon on tooth pick appearance).
- Thinning of the skin with easy bruising and purple striae.
- Bone tenderness and pain
- Slow healing of the wounds
- Proximal muscle weakness
- High blood pressure
- High blood sugar levels
- Depression and anxiety
- Pathological bone fractures
- Irregular menstrual cycles
- Sexual dysfunction
A history of use of steroid drugs as well as typical signs and symptoms are helpful in the initial diagnosis of Cushing syndrome. The following laboratory tests may be done for final diagnosis:
- Blood cortisol levels
- Blood sugar
- Dexamethasone suppression test.
- 24 hr urine for cortisol and creatinine
- ACTH levels
- ACTH stimulation test
- Abdominal CT scan to look for tumors
- Pituitary MRI.
Treatment: The first step in the treatment is to determine the underlying cause.
1. If the syndrome is due to excess intake of steroid drugs they need to be stopped. The doctor may decide either to stop completely, taper or reduce the dose depending on the underlying cause of taking that medicine.
2. If a tumor is the cause for excess hormone secretion surgery may be the best choice to remove the tumor.
3. Sometimes drugs like ketoconazole, metyrapone that inhibit the synthesis of cortisol in the body may be used.
4. Radiation therapy may be used for tumors that cannot be removed by surgery alone.