SIADH
What is SIADH?
To function properly, every cell in our bodies needs to a certain level of salt. When the salt balance in the body is disturbed, many things can start going wrong.
Antidiuretic hormone (ADH), also known as vasopressin, controls the way your body retains or secretes water. ADH causes the body to retain water, which lowers the salt concentration throughout the body. The syndrome of inappropriate secretion of antidiuretic hormone, SIADH for short, occurs when your body makes too much ADH.
SIADH is the most common cause of low body salt (known as hyponatremia). [1]
SIADH is caused by too much antidiuretic hormone in the body, which reduces salt concentration in the blood.
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Antidiuretic
A substance that suppresses the production and excretion of urine.
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Hormone
A chemical substance secreted in one part of an organism and transported to another part of that organism, where it has a specific effect.
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Ellison, D.H. & Berl, T. (2007). The Syndrome of Inappropriate Antidiuresis. New England Journal of Medicine 356: 2064–2072.
Causes
SIADH can be the result of numerous different disorders, including, but not limited to:
Brain and nerve disorders:
- Meningitis and encephalitis;
- Brain abscess;
- Head injury;
- Stroke;
- Guillain-Barre syndrome;
- Hypothalamus or pituitary gland disorders;
- Multiple sclerosis;
- Vasculitis;
- Shy-Drager syndrome;
- Delirium tremens ('the shakes'), and;
- Psychosis.
Cancer:
Lung disorders
Medications:
SIADH can be a side effect of certain medications and substances, such as:
- Antidepressants;
- Carbamazepine;
- Hormone treatments (vasopressin, oxytocin);
- Antipsychotic drugs;
- Quinolones;
- Cyclophosphamide, and;
- MDMA ('ecstasy').
Other causes:
- After-effects of surgery;
- Genetic disorders, such as porphyria, and;
- Unknown causes.
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Carcinoma
Cancer of the tissues lining the internal organs, body cavities, surfaces and tubes.
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Delirium tremens
An acute condition caused by alcohol withdrawal that causes tremors, anxiety, sweating and hallucinations. Colloquially called 'the D.Ts'.
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Encephalitis
Inflammation of the brain, usually caused by a viral infection.
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Endometrial
Relating to the internal lining of the uterus.
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Hormone
A chemical substance secreted in one part of an organism and transported to another part of that organism, where it has a specific effect.
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Hypothalamus
A small part of the brain that carries out many functions, in particular the communication between the nervous system and the endocrine system (via the pituitary gland).
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Lymphoma
A tumor of lymph tissue, which is rich in lymphocytes, small white blood cells that have specific immune responses.
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Psychosis
An abnormal mental state characterized by a loss of contact with reality.
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Shy-Drager syndrome
A rare genetic disease that causes progressive death of nerve cells in the brain and spinal cord.
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Guillain-Barre syndrome
An autoimmune condition triggered by an acute infection, which leads to inflammation of peripheral nerves causing a characteristic pattern of paralysis that begins at the feet and spreads up the body.
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Nasopharyngeal cancer
Cancers arising in the lining of the nose, sinuses and throat.
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Porphyria
A group of conditions caused by defective enzymes, which leads to a build-up of metallic compounds (known as porphyrins) normally found in tissues. The abnormal accumulation of porphyrins affects the skin, digestive system and/or nervous system, leading to symptoms such as skin blisters, abdominal pain or seizures.
Signs and symptoms
Symptoms of SIADH can appear and become more severe as the body's salt concentration drops. These symptoms may include [2] [3] :
- Nausea, vomiting;
- Loss of appetite;
- Stomach aches;
- Confusion, hallucinations, irritability and personality changes;
- Headache;
- Incontinence;
- Weakness;
- Unsteady balance and increased chance of falls;
- Muscle cramps, and;
- Seizures, coma.
Many people with mild SIADH often have no symptoms, or their symptoms may not be recognized as SIADH symptoms. This is especially common in elderly people, where reduced mental abilities - for example, poor concentration or forgetfulness - are often blamed on age or other causes [4] .
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Coma
A state of deep and prolonged unconsciousness.
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Incontinence
The uncontrollable loss, small or large, of bladder or bowel control, resulting in leakage of their contents.
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Nausea
A sensation of sickness and unease, typically felt in the stomach, often accompanied by the urge to vomit. Nausea is a common symptom with many possible causes.
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Stomach
The first major site of digestion. An organ in the abdomen where food incoming from the food pipe is digested with enzymes and acidic gastric juices.
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Hallucinations
A false perception of something that is not actually there. The perception can be visual or aural.
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Hannon, M.J. & Thompson, C.J. (2010). The syndrome of inappropriate antidiuretic hormone: prevalence, causes and consequences. European Journal of Endocrinology 162: S5–S12.
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Hoorn, E.J., Lubbe, N. van der & Zietse, R. (2009). SIADH and hyponatraemia: why does it matter? NDT Plus 2: iii5–iii11.
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Gross, P. (2012). Clinical management of SIADH. Therapeutic Advances in Endocrinology and Metabolism 3: 61–73.
Methods for diagnosis
Your doctor will suspect SIADH if you display symptoms and have a medical condition or history that would put you at risk of SIADH. To confirm the diagnosis and rule out other conditions, urine tests and blood tests will be done to check your salt levels.
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Blood tests
During a blood test, blood can be drawn using a needle or by a finger prick. Your blood can then be analyzed to help diagnose and monitor a wide range of health conditions.
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Urine tests
A routine examination of the urine for cells, microbes, or chemicals that can indicate a range of different illnesses.
Types of treatment
Treatment of SIADH can take several forms:
- A high-salt infusion can be used to treat acute cases of SIADH in the short term;
- SIADH can be cured if the underlying medical condition or cause is treated. For instance, if SIADH is the side effect of a particular medication, adjusting the dose or using an alternative medication often helps reverse SIADH;
- If the underlying cause is not treatable, it is often best to treat SIADH with fluid restriction, which is limiting the amount of water a person drinks. Your doctor will advise you how to safely do this;
- Treatment with diuretic medication, such as frusemide, can encourage the body to get rid of excess water, and;
- Medications called 'vaptans', or vasopressin-receptor antagonists, have recently begun to be used to treat SIADH. Vaptans limit ADH activity; however, these medications are not widely available. [1]
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Ellison, D.H. & Berl, T. (2007). The Syndrome of Inappropriate Antidiuresis. New England Journal of Medicine 356: 2064–2072.
Potential complications
If not treated, SIADH can lead to very low salt concentrations, which can interfere with the function of many of the body's systems, and is associated with a significant rise in illness and death rates [2] .
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Hannon, M.J. & Thompson, C.J. (2010). The syndrome of inappropriate antidiuretic hormone: prevalence, causes and consequences. European Journal of Endocrinology 162: S5–S12.
References
- Ellison, D.H. & Berl, T. (2007). The Syndrome of Inappropriate Antidiuresis. New England Journal of Medicine 356: 2064–2072.
- Hannon, M.J. & Thompson, C.J. (2010). The syndrome of inappropriate antidiuretic hormone: prevalence, causes and consequences. European Journal of Endocrinology 162: S5–S12.
- Hoorn, E.J., Lubbe, N. van der & Zietse, R. (2009). SIADH and hyponatraemia: why does it matter? NDT Plus 2: iii5–iii11.
- Gross, P. (2012). Clinical management of SIADH. Therapeutic Advances in Endocrinology and Metabolism 3: 61–73.
- Murtagh, J. (2008). John Murtagh’s Patient Education (Australian edition.). North Ryde, N.S.W.: McGraw-Hill Book Company Australia.
- Zietse, R., Lubbe, N. van der & Hoorn, E.J. (2009). Current and future treatment options in SIADH. NDT Plus 2: iii12–iii19.
- Castillo J.J. Vincent M. & Justice E. (2012). Diagnosis and Management of Hyponatremia in Cancer Patients. The Oncologist 17: 756–765.
- Charmandari E. Nicolaides N.C. & Chrousos G.P. (2014). Adrenal insufficiency. The Lancet 383: 2152–2167.
- Efficacy of Phenytoin Against Hyponatremic Seizures Due to SIADH After Administration of Anticancer Drugs in a Neonate. (2002). Published online: 12 April 2002; | doi:10.1038/sj/jp/7210657 22. Accessed from link here
- Ellison D.H. & Berl T. (2007). The Syndrome of Inappropriate Antidiuresis. New England Journal of Medicine 356: 2064–2072.
- Esposito P. Piotti G. Bianzina S. et al. (2011). The Syndrome of Inappropriate Antidiuresis: Pathophysiology Clinical Management and New Therapeutic Options. Nephron Clinical Practice 119: c62–c73.
- Gross P. (2012). Clinical management of SIADH. Therapeutic Advances in Endocrinology and Metabolism 3: 61–73.
- Hannon M.J. & Thompson C.J. (2010). The syndrome of inappropriate antidiuretic hormone: prevalence causes and consequences. European Journal of Endocrinology 162: S5–S12.
- Hoorn E.J. Lubbe N. van der & Zietse R. (2009). SIADH and hyponatraemia: why does it matter? NDT Plus 2: iii5–iii11.
- Milionis H.J. & Elisaf M.S. (2002). Hyponatremia and SIADH. CMAJ: Canadian Medical Association Journal 167: 450.
- siadh. Accessed 10 October 2014 from link here
- Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) | CHOP | The Children’s Hospital of Philadelphia. Accessed 10 October 2014 from link here
- Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) - Online Medical Encyclopedia - University of Rochester Medical Center. Accessed 10 October 2014 from link here
- Treatment of hyponatremia: Syndrome of inappropriate antidiuretic hormone secretion (SIADH) and reset osmostat. Accessed 10 October 2014 from link here
- Zietse R. Lubbe N. van der & Hoorn E.J. (2009). Current and future treatment options in SIADH. NDT Plus 2: iii12–iii19.
7 Most frequently asked questions (FAQs)
SIADH is a condition that occurs when your body makes too much antidiuretic hormone (ADH), also known as vasopressin. This substance controls the way your body retains or secretes water. What are the symptoms of SIADH? Many people with mild SIADH often have no symptoms. For others, symptoms can appear and become more severe as the body's salt concentration drops. These symptoms may include: nausea and vomiting; loss of appetite; stomach aches; confusion, hallucinations, irritability and personality changes; headache; incontinence; weakness; muscle cramps; seizures, and; coma. SIADH can have numerous causes, including various cancers, brain and nervous system damage, lung problems, reaction to certain medications, and other factors. Your doctor will suspect SIADH if you display symptoms and have a medical condition or history that would put you at risk of SIADH. To confirm the diagnosis and rule out other conditions, urine tests and blood tests will be performed to check the salt levels in your urine and blood. SIADH can be cured if the underlying cause is treated. SIADH is often treated with fluid restriction (minimizing your water intake). Medications can limit ADH activity (vasopressin-receptor antagonists) or encourage water excretion (diuretics). Short-term treatment of acute cases can take the form of a high-salt infusion. SIADH will clear when its cause has been treated. SIADH can have a significant effect on your health, so it is important to treat it.
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