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Endocrine System: How Hormones Work?
adrenal glands located above the kidneys.
The adrenal glands and their hormones are vital for life
The adrenal glands are small triangle-shaped glands located on top of the kidneys. They produce hormones such as cortisol, aldosterone and adrenaline.
These hormones help to regulate essential body functions that include blood pressure, metabolism, salt homeostasis and the body’s response to stress and infections. The release of hormones by the adrenal glands is controlled in part by the hypothalamus and pituitary gland in the brain. The kidneys and the body’s sympathetic nervous system also interact with the adrenal glands. The adrenal glands are composed of two parts: the cortex (outer part) and the medulla (inner part). Each part is responsible for producing different hormones. Cortisol, aldosterone and androgens are produced at the cortex and adrenaline and noradrenaline at the medulla.Adrenal hormones
Cortisol: A glucocorticoid hormone that helps the body to respond to illness and injury. It also helps to maintain normal blood pressure, glucose levels and sleep-wake rhythm.Common symptoms of adrenaline insufficiency.Common symptoms of adrenaline insufficiency.
The common symptoms of adrenal insuffiency
Aldosterone: A mineralocorticoid hormone that stabilises blood pressure, salt and water in the body.
Androgens: These hormones are also known as “male” hormones. The most commonly known androgen is testosterone. Androgens are usually thought of as male hormones, but the females produce a small number of androgens too.
Adrenaline (epinephrine) and noradrenaline (norepinephrine): These hormones are sometimes called the “fight or flight” hormones.
They make the heart pump faster and stronger, regulate blood pressure and glucose levels.
Like cortisol hormones, these hormones are released in larger amounts when the body faces stressful situations.
Can we live without adrenal glands?
The adrenal glands produce essential hormones that the body cannot function without. Babies and children who do not make enough cortisol or aldosterone hormones can develop a life-threatening medical condition known as adrenal crisis. In adrenal crisis, the blood pressure and glucose levels are low. There is also an imbalance of essential salts in the body. An adrenal crisis usually happens in times of stress such as during an acute illness, surgery or if a child with an adrenal disorder is not taking his or her medications appropriately. What common conditions affect the adrenal glands? Adrenal gland disorders happen when the adrenal glands make too much or too little of one or more hormones. Some conditions are temporary whereas others are life-long. Causes of adrenal disorders include: > Genetic mutations which affects the production of adrenal hormones e.g. congenital adrenal hyperplasia, adrenal leukodystrophy > Autoimmune diseases involving the adrenal glands > Damage to the adrenal glands through injury, infection or blood loss. > Adrenal tumours > Hypothalamus or pituitary gland disorders in the brain which regulate release of adrenal glands hormones > Certain medications, such as prolonged use of steroids. The symptoms of adrenal gland disorders depend on which hormones are affected and if it is too much or too little. Many of the symptoms may be similar to other illnesses and need to be correlated with the history and examination by the specialist doctor.Adrenal insufficiency (not enough adrenal hormones)
Adrenal insufficiency is a condition in which the body is unable to produce enough cortisol and sometimes aldosterone. This usually happens due to genetic conditions or damage to the adrenal glands following surgery, injury, blood loss or an infection. Adrenal insufficiency can also happen when the pituitary gland in the brain fails to produce adrenocorticotrophic hormone (ACTH), which is the signal that regulates adrenal function. Long-term steroid medications such as prednisolone, hydrocortisone or dexamethasone may also results in suppression of production of ACTH resulting in the adrenal glands producing less endogenous cortisol. Hence children who had received prolonged or high doses of steroids need to have their adrenal function monitored. A child with adrenal insufficiency may have these symptoms: > Unexplained poor weight gain > Easily tired > Severe illness > Low blood pressure and glucose levels, and > Salt cravings. They may also appear to have unusually dark skin pigmentation especially at the skin creases, and gums. In certain adrenal condition, such as congenital adrenal hyperplasia, the baby or child may have abnormal sexual characteristics e.g. enlargement of the clitoris in girls and penile enlargement in young pre-pubertal boys.Cushing syndrome
Cushing syndrome is a condition that is due to excess cortisol. It can be from an outside source for example taking long-term or high doses of steroid medications
The common symptoms of Cushing Syndrome.
More rarely, Cushing syndrome can be due to excess production of the hormone by the body itself such as by an adrenal tumour or growth in the pituitary gland, which stimulates the adrenal glands to make too much hormones.
Common symptoms in children are: > Weight gain, more prominent at the face and belly > Poor growth despite weight gain > Muscle wasting > Increased hair growth over the body. Complications include: > High blood pressure > Diabetes > Prone to infections > Thin, easily bruised skin > Brittle bones, and > Irregular menses in adolescent girls.Diagnosis and testing
Diagnosis of adrenal disorders is based on the history, physical examination and blood test that measure the amount of adrenal hormones in the body. Interpretation of adrenal hormone levels must be correlated with the probable cause and clinical picture. Sometimes additional endocrine (hormone) stimulation tests or imaging of the brain and adrenal glands are needed. Treatment options If the adrenal gland does not make enough hormones, treatment consists of replacing these hormones with medication; e.g. steroid (glucocorticoids) medication is needed to replace cortisol. Some children may also need to take Fludrocortisone medication to replace aldosterone. During acute illness or surgery, the steroid medication needs to be taken in larger amounts. In rare cases where the adrenal gland is producing too much hormones e.g, certain adrenal tumours, medications are given to suppress the hormones or to relieve the symptoms. The underlying cause for the adrenal disorder must also be addressed, e.g. surgical removal of tumours where indicated. The duration of treatment depends on the underlying cause. Medications often need to be taken life-long in genetic causes. In others, such as in adrenal insufficiency due to tapering off of long-term steroid use, treatment is only needed until the adrenal glands “wake up” and begin producing its own hormones again. With treatment, the symptoms of adrenal insufficiency can be controlled enabling children with this condition to live normal lives. However, regular specialist follow-up and blood testing are important for treatment adjustment to ensure proper growth, development and prevention of adrenal crisis.Dr Jeanne Wong Sze Lyn is a consultant paediatrician and paediatric endocrinologist. This is the fourth article in a monthly series called Hormones and Kids. For more information, email starhealth@thestar.com.my. The information provided is for educational purposes only and should not be considered as medical advice. The Star does not give any warranty on accuracy, completeness, functionality, usefulness or other assurances as to the content appearing in this article. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.
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