Cancer is the abnormal growth of cells and tissues; when it occurs in the lungs, it interferes with the exchange of gases in the lungs. Lung cancer may be associated with paraneoplastic syndromes, a group of disorders that occur in relation to the presence of cancer in the lungs. Sodium imbalance may occur as a consequence of lung cancer-related paraneoplastic syndromes.
Types of Lung Cancer
There are two main types of lung cancer: non-small cell lung cancer, or NSCLC, and small cell lung cancer or SCLC. According to "Pocket Medicine," NSCLC constitutes 75 percent of cancers that affect the lungs; the other 25 percent is caused by SCLC. NSCLC and SCLC are cancers that originate within the lungs; cancer may also manifest in the lungs as a result of metastasis -- the spread of cancer from other organs of the body.
SCLC and Sodium Imbalance
SCLC is observed almost exclusively in smokers. According to the Centers for Disease Control and Prevention, smoking is an important risk factor for SCLC; it is responsible for 90 percent of lung cancer deaths in men and 80 percent of lung cancer deaths in women. According to a 2008 "Clinical & Experimental Otorhinolaryngology" article, 70 percent of SIADH, or syndrome of inappropriate antidiuretic hormone secretion, result from SCLC. SIADH results from the abnormal secretion of the antidiuretic hormone, or ADH, from SCLC; ADH stimulates the kidneys to hold water, thereby reducing water excretion. Over time, the retention of water by the kidneys result in increased volume of water in the blood. It is important to maintain known sodium levels in the blood in order to prevent adverse consequences; increasing the amount of water and blood, reduces the concentration of sodium in the blood.
Symptoms of Low Blood Sodium
Sodium is important in volume regulation, both in the cells and in the blood; sodium can be described as a "water magnet" referring to the tendency of sodium to attract more water when its concentration is increased in any compartment, in cells or in blood. Sodium imbalance produces symptoms because it causes changes in cell volume, which affects the function of cells. Hyponatremia, or low blood sodium, can result in altered mental status; decreased consciousness, confusion and hallucinations are all conditions involving changes in mental status, which can occur in hyponatremia. Other symptoms associated with hyponatremia include headache, fatigue, loss of appetite, muscle spasms, muscle weakness, irritability, nausea and vomiting.
Management of Low Blood Sodium in People with Lung Cancer
A person with lung cancer has a big enough problem dealing with the cancer alone; lung cancer rarely presents as a non-active growing mass in the lungs, but rather it's a growing mass with lots of problems associated with it, including hyponatremia. Lung cancer must be managed aggressively to prevent rapid deterioration of health. Whenever hyponatremia is suspected, a blood test can be done to evaluate blood sodium levels. A urine analysis can also be useful in determining the likely cause of hyponatremia; in lung cancer, a urine that is more concentrated than normal is typical of an ADH-secreting cancer. Treatment of an ADH-secreting lung cancer should result in improvement of hyponatremia. Severe cases of hyponatremia are treated with infusion of saline -- a solution containing sodium -- into a vein.
References
- "Clinical & Experimental Otorhinolaryngology"; Syndrome of Inappropriate Antidiuretic Hormone (SIADH) Secretion Caused by Squamous Cell Carcinoma of the Nasopharynx; Minwook Yoo, MD, et al.; 2008
- Medline Plus: Hyponatremia
- "Pocket Medicine"; Nephrology; Marc S. Sabatine M.D., M.P.H.; 2004
