Chemotherapy and radiation therapy (RT) often cause nausea and vomiting. This can lead to dehydration and care needs to be taken with the patient's fluid balance.
Sometimes oncology patients can develop the opposite problem:
Inappropriate Anti-Diuretic Hormone Secretion (also called SIADH)
Due to continuous release of ADH from pituitary irrespective of serum osmolality.
Leads to hypo-osmolality and water intoxication.
Caused by:
- Underlying malignancy (lymphomas and leukemias)
- Therapy (Vincristine, cyclophosphamide, ifosphamide and cisplatin)
- CNS and pulmonary lesions
- Stress, pain, infection, surgery and mechanical ventilation
Clinical Features
- Oliguria and weight gain
- Lethargy, confusion, seizures and coma - which can lead to death
Biochemical Features
- Increased ADH secretion
- Increased “free water” conservation and hypo-osmolality (<280 mOsm/L)
- Hyponatremia (Na < 135 mEq/L)
- Concentrated urine with increased urine specific gravity
Therapy
- Fluid restriction - hydrate with normal saline limited to insensible losses
- Lasix (Furosemide 1 mg/kg to increase diuresis)
- Hypertonic saline if severe
