From the Guidelines
Syndrome of Inappropriate Antidiuretic Hormone (SIADH) symptoms include general weakness, confusion, headache, and nausea, which can progress to life-threatening manifestations such as seizures, coma, and death if left untreated. These symptoms occur due to hyponatremia (low sodium levels in the blood) caused by excessive water retention, as evidenced by a study published in the journal Chest 1. The severity of symptoms typically correlates with the degree of hyponatremia and the acuity of hypoosmolality.
Some key symptoms and signs of SIADH include:
- Hyponatremia (serum sodium < 134 mEq/L)
- Hypoosmolality (plasma osmolality < 275 mosm/kg)
- Inappropriately high urine osmolality (> 500 mosm/kg)
- Inappropriately high urinary sodium concentration (> 20 mEq/L)
- Absence of hypothyroidism or adrenal insufficiency or volume depletion, as described in the study 1.
Laboratory findings in SIADH include urine osmolality of > 300 mosm/kg, urinary sodium level of > 40 mEq/L, serum osmolality of < 275 mosm/kg, and serum uric acid concentration of < 4 mg/dL, according to the evidence 1. It is essential to distinguish SIADH from other non-ADH-mediated causes of hyponatremia, such as paraneoplastic hyponatremia secondary to elevated atrial natriuretic peptide 1.
The management of SIADH is based on expert opinion, and recommended treatments include free water restriction, hypertonic 3% saline IV, demeclocycline, lithium, and vasopressin 2 receptor antagonists, as discussed in the study 1. Early detection and appropriate management can prevent severe hyponatremia and its associated morbidity and mortality 1.
From the Research
Symptoms of SIADH
The symptoms of Syndrome of Inappropriate Antidiuretic Hormone (SIADH) secretion are primarily related to hyponatremia, which is the most frequent electrolyte disorder in SIADH patients 2. The symptoms may include:
- Anorexia
- Vomiting
- Confusion
- Seizures
- Coma
- Death (in severe cases) 3 These symptoms generally occur when hyponatremia is severe (less than or equal to 125 meq/L) 3. Additionally, cerebral edema with symptoms such as lethargy, weakness, nausea, and coma can be a dangerous clinical feature of hyponatremia in SIADH 4.
Factors Influencing Symptom Severity
The severity of symptoms in SIADH patients can depend on the stage of the disorder and the rate of change of natremia 4. Early diagnosis and treatment are necessary to prevent morbidity and mortality associated with hyponatremia in SIADH patients 4.
Treatment-Related Symptoms
Treatment of SIADH can also cause symptoms, such as: