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Saturday, January 14, 2012

Addison disease

Authors : Drs Anne Peters and Pejman Cohan USC Westside Center for Diabetes and Beverly Hills. 2008-05-02

The adrenal glands are two pyramid-shaped glands that sit on top of each kidney. Anatomically, the adrenal glands are composed of an outer compartment called the adrenal cortex and an inner compartment called the adrenal medulla. The adrenal medulla is regulated by the nervous system and secretes three distinct hormones: epinephrine (adrenaline), norepinephrine (noradrenaline), and dopamine. These are often referred to as the “fight or flight” hormones. The adrenal cortex can be further subdivided into three regions, each of which secretes its particular steroid hormone. The adrenal cortex is primarily regulated by the pituitary gland (an endocrine gland located in the brain) and releases more than 50 steroid hormones. Among these are the hormones called cortisol and aldosterone. Cortisol and aldosterone are considered life-sustaining hormones because they regulate blood pressure, blood sugar, and electrolyte balance, and also play an important role in our body’s response to stress.

Adrenal glands
 
ADRENAL INSUFFICIENCY:
 
Adrenal insufficiency occurs when the adrenal glands produce inadequate amount of one or more of the hormones listed above, such as cortisol and aldosterone. Thomas Addison first described the symptoms and potentially fatal consequences of absent adrenal function (termed adrenal insufficiency or hypoadrenalism) in 1855. For this reason, adrenal insufficiency is often called Addison’s disease. There are two types of adrenal insufficiency:
 
1) Primary adrenal insufficiency: In primary adrenal insufficiency, the adrenal glands are either damaged or destroyed. This adrenal damage or destruction may occur from a variety of causes, which will be discussed below

2) Secondary adrenal insufficiency: In secondary adrenal insufficiency, the adrenal glands are actually healthy, but fail to function properly because they are missing the pituitary signals that stimulate them to release cortisol. The absent pituitary signal is another hormone called ACTH (Adrenocorticotropic Hormone). Any type of pituitary or hypothalamic disease can result in loss of the ACTH signal, and in turn, lead to secondary adrenal insufficiency. Because the adrenal hormone aldosterone is not primarily regulated by pituitary ACTH, patients with secondary adrenal insufficiency continue to produce aldosterone.

SYMPTOMS OF ADRENAL INSUFFICIENCY:
 
The symptoms and signs of adrenal insufficiency are listed in the table below; the most common symptoms are fatigue, weakness, poor appetite, and weight loss. The number of + signs shown correlates with the approximate frequency of the symptom/sign listed ( that is, more + signs mean the symptom/sign is more likely to be present). Note, that certain signs such as skin darkening or low potassium levels are primarily seen in primary adrenal insufficiency, whereas many of the other signs/symptoms overlap between the two types of adrenal insufficiency.                                                                        

           

Approximate Frequency


Primary                                   Secondary

Symptoms/Signs

 
Fatigue/Weakness                                ++++                                       ++++

Poor Appetite                                      ++++                                       ++++

Weight Loss                                         ++++                                       ++++

Nausea, Diarrhea                                 +++                                         +++

Muscle, joint, abdominal pain               ++                                            ++

Light-headedness upon standing           ++                                            +

Low blood sodium level                       +++                                         +

Skin darkening                                     +++

Low blood potassium level                   +++                                        
 
As you can see, the signs and symptoms of adrenal insufficiency are very non-specific, meaning that they are common to many other disorders.  Therefore, a wise clinician should always consider adrenal insufficiency on the differential diagnosis. The severity of the symptoms depends on the rate and degree of loss of adrenal function.  The presentation of adrenal insufficiency (especially secondary adrenal insufficiency) may be subtle and go undetected for many years until the stress of another illness precipitates an adrenal crisis and unmasks the disease.  President John F. Kennedy suffered from Addison’s disease.  Historical records indicate that while visiting London in 1947, Kennedy developed a severe constellation of symptoms including nausea, vomiting, weakness and low blood pressure. His condition was so dire at that time, that he was given the last rites by the Roman Catholic Church. Of course Kennedy survived that illness but was dependent on cortisol replacement by both pills and injections.
 
CAUSES OF ADRENAL INSUFFICIENCY:
 
Primary Adrenal Insufficiency –  Primary adrenal insufficiency is an uncommon disorder, with a prevalence of approximately 50 – 100 cases per one million adults.

The leading cause of primary adrenal insufficiency in developed countries is an autoimmune disorder in which the body’s immune system mounts an attack against its own adrenal glands. Other immune disorders (such as Hashimoto’s Thyroiditis, Type 1 diabetes mellitus, pernicious anemia, or vitiligo) may also be present; resulting in a condition called Autoimmune Polyendocrinopathy Syndrome (APS). Patients with adrenal insufficiency as part of the APS are typically female.  In less-developed countries, tuberculosis and fungal infections of the adrenal glands are much more common causes of adrenal insufficiency. These infections are also more commonly seen in immunocompromised persons such as those with HIV. HIV infection itself may also damage the adrenal glands and result in adrenal insufficiency. Severe bacterial infections in patients in the intensive care unit may lead to adrenal hemorrhage (bleeding), particularly if the patient is receiving blood thinners (this condition is called Waterhouse-Friderichsen Syndrome). Certain medications (ketoconazole, etomidate) inhibit cortisol production by the adrenal glands and may lead to adrenal insufficiency. Certain cancers (especially lung cancer) may spread to the adrenal glands and cause adrenal failure. Finally, congenital (present at birth) and genetic disorders are rare causes of adrenal insufficiency.

Secondary Adrenal Insufficiency – Secondary adrenal insufficiency is much more common than primary adrenal insufficiency. The most frequent cause of secondary adrenal insufficiency is an iatrogenic condition. Iatrogenic means that a health care provider caused the condition unintentionally. This primarily occurs when high-dose steroids are given to patients to treat certain medical disorders, such as asthma, rheumatic disease, or other inflammatory conditions. Through a process called feedback inhibition, the high-dose steroids suppress pituitary production of ACTH. Since ACTH is necessary to stimulate adrenal cortisol release, the lack of ACTH will in turn lead to adrenal insufficiency. Such patients are at particular risk for developing adrenal insufficiency if the high dose steroids are stopped abruptly without a taper. Iatrogenic adrenal insufficiency is generally reversible. By gradually tapering the dose of steroids, pituitary production of ACTH may slowly return and secondary adrenal insufficiency may resolve. The dose and duration of prior exposure are the main determinants of how quickly this recovery occurs. Other causes of secondary adrenal insufficiency include pituitary or hypothalamic disorders, most commonly tumors. Pituitary radiation and surgery may also result in secondary adrenal insufficiency.
 
DIAGNOSTIC TESTING:

Diagnostic testing for adrenal insufficiency involves laboratory tests to find out if the hormone levels are deficient and then further testing to determine the cause. The first step in diagnostic testing is to confirm that blood cortisol levels are low. Since cortisol levels fluctuate during the day, it is important to have blood testing done in the early morning. Cortisol levels are highest during the early morning. A morning blood cortisol level of less than 3 mcg/dL is highly suspicious for adrenal insufficiency. In most cases, an ACTH Stimulation Test (also known as a Cortrosyn Simulation Test) is done to establish the diagnosis, and can help distinguish primary from secondary adrenal insufficiency. The ACTH Stimulation test involves measurement of blood cortisol levels immediately before as well as 30 and 60 minutes after an injection of 250 mcg of ACTH. ACTH is high in primary adrenal insufficiency and tends to be low in secondary adrenal insufficiency. This test is considered normal if the cortisol levels peaks above 18 mcg/dL after injection of ACTH. CT scan of the adrenal glands may also be performed when the cause of primary adrenal insufficiency is unclear.


TREATMENT:

Treatment of adrenal insufficiency involves the administration of adrenal hormones to mimic the normal output by the adrenal glands. This is best accomplished by giving hydrocortisone (Cortef) orally in two to three divided doses each day. An alternative is to give a longer acting steroid called prednisone. Since prednisone has a longer half life than hydrocortisone, it may be administered once or twice per day. In recent years, as we have come to better understand the normal output of the adrenal glands, there is a trend to using a lower total daily dose of hydrocortisone. Hydrocortisone replacement generally suffices in patients with secondary adrenal insufficiency. However, as patients with primary adrenal insufficiency are also deficient in aldosterone, they must take a synthetic analog of aldosterone (called fludrocortisone) along with hydrocortisone. Fludrocortisone is taken orally, once or twice daily.

IN CASE OF AN EMERGENCY:

The prognosis of adrenal insufficiency is generally quite good as long as the patient remembers to take his or her medications consistently on a daily basis and is under the close care of an endocrinologist.  An important point to remember is that the normal adrenal glands release higher amounts of cortisol during periods of physical stress. The higher amount of cortisol helps the body overcome the stressor. Any acute illness, trauma, hospitalization, or surgery constitutes increase physical stress.  Under these circumstances, patients with adrenal insufficiency must double or triple their maintenance dose of hydrocortisone.  This is referred to as “stress-doses” of steroids. Once the stressor improves and/or resolves, the dose of hydrocortisone is gradually weaned back down to the maintenance dose. If the illness or “stressor” includes vomiting and/or diarrhea, a person with adrenal insufficiency must seek immediate medical care to receive hydrocortisone by injection to ensure adequate absorption. A hydrocortisone emergency kit is also available for emergency situations in which access to medical care may be delayed. Patients with adrenal insufficiency must always wear an alert bracelet or necklace that identifies them as having adrenal insufficiency so that emergency personnel can provide stress doses of steroids in the event of trauma, surgery, or hospitalization. Failure to provide “stress doses” of steroid during critical illness may lead to an adrenal crisis which may include loss of consciousness, shock or other potentially fatal consequences.
   
REFERENCES:

Trainer PJ and Besser GM, Addison’s Disease, in Comprehensive Clinical Endocrinology, Besser GM and Thorner MO, Eds. Mosby Publishers, Third Edition. 2002. Pages 203-212.

National Adrenal Disorders Foundation: www.NADF.US