Adrenal Insufficiency: The Basics
What is adrenal insufficiency?
Adrenal insufficiency is a term used to describe the inability of the adrenal glands to produce cortisol (and sometimes also aldosterone). Both hormones are regulators that play key roles in how the body functions.
Cortisol is known as the body’s main stress hormone.
- Raises blood sugar, regulates the body's immune system, and reduces inflammation
- Provides glucose the brain needs to function
- Main hormone that is instrumental in fight or flight situations
Aldosterone helps to regulate and control blood pressure.
- Prevents dehydration thereby playing a role in regulating blood pressure
- Regulates salt levels in the bloodstream
- Regulates the amount of potassium released in the urine
Root causes of AI in children:
Genetic
AI can be inherited through genes passed down from mom and dad. AI can also be caused by a new genetic mutation/abnormality which causes dysfunction of the adrenal glands. The most common genetic form of AI is congenital adrenal hyperplasia also known as CAH.
Autoimmune
Autoimmune adrenal insufficiency is the most common form of Addison's disease, a condition in which the adrenal glands stop producing adrenal hormones. This insufficiency occurs when a person's own immune system mistakenly attacks the adrenal cortex.
Acquired
Long term use of steroids (for example Asthma) suppress ones own release of hormones (Cortisol) during use. Even after steroid therapy has stopped, the body's systems may need time to recover.
HPA Axis
There are three organs, the hypothalamus, pituitary gland, and adrenal gland, that work together in a feedback loop to create and maintain a balance of hormones throughout the day. The loop is called the HPA axis (or formally the hypothalamic-pituitary-adrenal axis). The HPA axis is functional to maintain homeostasis and, during times of stress, facilitates increased production of cortisol.
Hypothalamus
A small area at the base of the brain and the first to receive the signal that the body is under stress. The hypothalamus responds to the signal by sending its own chemical message to the pituitary gland.
Pituitary Gland
A pea-sized gland at the base of the brain that receives and responds to the signal from the hypothalamus by sending chemical messages to the adrenal glands.
Adrenal Glands
Walnut-sized organs on top of each kidney where cortisol and aldosterone are produced and released. The release of cortisol in amounts that the body needs in turn sends the message to both the pituitary gland and the hypothalamus that adequate amounts of cortisol have been produced.
In healthy children, the HPA axis achieves a predictable release of hormones and the body is stable. For children with AI, one of the organs in the HPA axis is not releasing hormones as it should. As a result, the body can no longer maintain a stable balance of glucose (sugar), salt, and fluids. Blood pressure, salt, and sugar levels quickly drop, the body becomes unstable, and without medical intervention, the child becomes critically ill. This requires urgent medical intervention and treatment to prevent a life-threatening condition called Adrenal Crisis.
Classifications of AI
You may have heard of the classification terms primary, secondary, or tertiary AI. (Some doctors even lump secondary and tertiary together into one bucket called “central AI.”) The classification depends on where the disruption/defect in the HPA axis is leading to a shortfall in hormone production. Abnormal function in any of the 3 organs in the HPA lead to low cortisol levels.
Primary Adrenal Insufficiency: The shortfall is in the adrenal glands, which are unable to produce cortisol and sometimes, aldosterone.
Central Adrenal Insufficiency: The shortfall is either in the pituitary gland (secondary AI) or the hypothalamus (tertiary AI).
Pediatric Endocrinologist
A pediatric endocrinologist is a doctor that evaluates, treats, and manages hormonal disorders in children; some even specialize in adrenal insufficiency and others in specific types of adrenal insufficiency like CAH. The pediatric endocrinologist works together with your child’s pediatrician and vice versa.
Co-management of your child allows each physician to focus on their specialty. While the pediatric endocrinologists work to ensure control of AI and achievement of growth and height milestones, the pediatrician maintains a focus on diagnosis, treatment, and prevention of childhood illnesses.
You can visit the Pediatric Endocrine Society website to find a pediatric endocrinologist in your area, or ask your pediatrician for a referral.
What to expect at a doctor appointment with a pediatric endocrinologist
The pediatric endocrinologist will begin by asking you many questions about current and past complaints. This will allow the doctor to get a complete understanding of your concerns and the child’s problems. The doctor will then proceed to the physical exam and, based on the information gathered, plan specific laboratory and radiologic tests needed to understand and diagnose your child’s medical condition causing AI.
Hormone and electrolyte levels can be checked from a blood draw including sodium, potassium, cortisol, adrenocorticotropic hormone (ACTH), and 17-OHP for patients with CAH.
ACTH blood levels and cortisol blood levels are used to help detect, diagnose, and monitor conditions associated with excessive or deficient cortisol in the body. The ACTH stimulation test measures how your adrenal glands react to the ACTH in your blood. It does this by measuring your body’s cortisol levels after injecting synthetic ACTH and drawing timed blood samples to measure cortisol before and after injecting ACTH.
A test to check for adrenal insufficiency due to pituitary disease (secondary adrenal insufficiency).
- MRI of the pituitary gland to rule out or evaluate central adrenal insufficiency.
- Computerized tomography (CT) scan of the abdomen to check the size/health of the adrenal glands.
