Syndrome of inappropriate antidiuretic hormone secretion

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Syndrome of inappropriate antidiuretic hormone secretion
Synonyms	SIADH, Schwartz-Bartter syndrome
Pronounce
Specialty	Endocrinology
Symptoms	Hyponatremia, low serum osmolality, high urine osmolality
Complications	Seizures, coma, cerebral edema
Onset
Duration
Types
Causes	Ectopic production of ADH, central nervous system disorders, pulmonary disorders, medications
Risks
Diagnosis	Laboratory tests, urine analysis, blood tests
Differential diagnosis	Cerebral salt-wasting syndrome, adrenal insufficiency, hypothyroidism
Prevention
Treatment	Fluid restriction, salt tablets, loop diuretics, vasopressin receptor antagonists
Medication
Prognosis
Frequency
Deaths

Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a condition characterized by excessive release of antidiuretic hormone (ADH) from the posterior pituitary gland or other sources. This syndrome was first described in 1957 by Schwartz et al.

Etiology

SIADH can be caused by various conditions, including malignant diseases, pulmonary diseases, central nervous system disorders, and the use of certain medications. The most common cause of SIADH is malignancy, particularly small cell lung cancer.

Pathophysiology

In SIADH, the excessive release of ADH leads to water retention and hyponatremia, a condition characterized by low levels of sodium in the blood. This is due to the fact that ADH increases the permeability of the renal tubules, allowing water to be reabsorbed back into the bloodstream.

Clinical Features

The clinical features of SIADH are primarily related to hyponatremia. Symptoms can range from mild, such as nausea and malaise, to severe, including seizures and coma. The severity of symptoms is generally related to the rapidity of onset and the degree of hyponatremia.

Diagnosis

Diagnosis of SIADH is based on clinical findings and laboratory tests. The key diagnostic criteria include hyponatremia, low serum osmolality, high urine osmolality, and clinical euvolemia.

Treatment

The treatment of SIADH is primarily aimed at correcting the hyponatremia and treating the underlying cause. This may involve fluid restriction, administration of saline solution, or the use of medications such as vasopressin receptor antagonists.

See Also

• Hyponatremia
• Antidiuretic hormone
• Posterior pituitary gland
• Central nervous system

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