Your patient has small cell carcinoma of the lung with persistent hyponatremia
Your patient has small cell carcinoma of the lung with persistent hyponatremia. With this disease there is an ectopic production of a hormone and "paraneoplastic syndrome." What hormone is involved and what is paraneoplastic syndrome?
The hormone involved in paraneoplastic syndrome in small cell carcinoma of the lung with persistent hyponatremia is antidiuretic hormone (ADH). ADH, also known as vasopressin, is a hormone that regulates the body's water balance. It is produced by the hypothalamus in the brain and stored in the pituitary gland. When ADH levels are high, the kidneys retain more water and urine output decreases. This can lead to hyponatremia, which is a low sodium level in the blood.
Paraneoplastic syndrome is a group of disorders that can occur in patients with cancer. These disorders are caused by the release of hormones or other substances from the cancer cells. The symptoms of paraneoplastic syndromes can vary depending on the specific disorder.
In patients with small cell carcinoma of the lung, the tumor cells can release ADH. This can lead to hyponatremia, which is the most common paraneoplastic syndrome associated with this type of cancer. Other paraneoplastic syndromes that can occur in patients with small cell carcinoma of the lung include:
- Cushing's syndrome: This syndrome is caused by the release of adrenocorticotropic hormone (ACTH) from the tumor cells. ACTH stimulates the adrenal glands to produce cortisol, which can lead to a variety of symptoms, including weight gain, muscle weakness, and high blood pressure.
- SIADH: This syndrome is caused by the release of ADH from the tumor cells. ADH causes the kidneys to retain water, which can lead to hyponatremia.
- Hypercalcemia: This syndrome is caused by the release of parathyroid hormone-related protein (PTHrP) from the tumor cells. PTHrP causes the bones to release calcium into the blood, which can lead to high blood calcium levels.
- Hyponatremia
- Hypervolemia (increased fluid volume in the blood)
- Dilute urine
- Low serum osmolality
- High urine osmolality