HWN Suggests

The suspect – SIADH

Hyponatraemia is one of the most common electrolyte abnormalities... with SIADH being an important but often under-recognised cause. It contributes to increased morbidity and mortality in a range of conditions, and has been associated with increased falls risk and osteoporosis, and altered mental state. Euvolaemic hyponatraemia with low serum sodium and osmolality, and raised urine osmolality in the absence of diuretic use or pseudohyponatraemia, are diagnostic of SIADH. Medication use should be reviewed, with consideration of further investigations if there is suspicion of malignancy or neurosurgical conditions.

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Articles of Interest

Syndrome of Inappropriate Anti-Diuretic Hormone (2nd edition)

The symptoms of SIADH relate to low sodium (hyponatraemia). Depending on the sodium level and how rapidly it occurs, they may be asymptomatic or present with non-specific symptoms:

Syndrome of inappropriate antidiuretic hormone

Syndrome of inappropriate antidiuretic hormone (SIADH) is defined as euvolemic, hypotonic hyponatremia secondary to impaired free water excretion, usually from excessive arginine vasopressin (AVP) release. Severe neurologic symptoms, such as altered mental status, seizure, and coma, may result from SIADH and these are always treated with hypertonic saline, with close monitoring to avoid overcorrection of serum sodium. Central pontine myelinolysis (osmotic demyelination syndrome) may occur with rapid correction of serum sodium in excess of 12 mEq/L/day.

Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH)

Deranged physiology in SIADH - The critical difference between normal physiology and what occurs in SIADH is the lack of an effective negative feedback mechanism. This results in continual ADH production, independent of serum osmolality. Ultimately, this leads to abnormally low serum sodium levels and relatively high urinary sodium levels, giving rise to the characteristic clinical features associated with SIADH.

Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH): A Root Cause Medicine Approach

SIADH can result from various conditions, including certain medications, central nervous system disorders, pulmonary diseases, and malignancies.

Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH): Optimal Management

The interest and knowledge on this clinical condition have increased considerably in recent years, so much so as to justify a change in its name, from SIADH to SIAD (syndrome of inappropriate antidiuresis), according to the fact that not all affected patients have increasing circulating ADH level, resulting from increased release by the pituitary gland or ectopic production.

Resources

PulseNotes

The condition is common and has an enormous number of causes. Once recognised fluid restriction is the mainstay of management with careful monitoring of plasma sodium levels.

StatPearls

Syndrome of inappropriate antidiuretic hormone ADH release (SIADH) is a condition defined by the unsuppressed release of antidiuretic hormone (ADH) from the pituitary gland or nonpituitary sources or its continued action on vasopressin receptors. The condition was first detected in two patients with lung cancer by William Schwartz and Frederic Bartter in 1967. They developed the classic Schwartz and Bartter criteria for diagnosing SIADH, which has not changed.