syndrome of inappropriate secretion

What is it ?

The syndrome of inappropriate secretion of ADH (vasopressin or antidiuretic hormone) are symptoms resulting from excessive secretion of the hormone by the hypothalamus. SADH is abbreviated.

How does it occur ?

The excessive syndrome of inappropriate secretion  causes decreased levels of sodium in the blood (hyponatremia). Hyponatremia is due to the inability of the kidney to remove water. Because urine is concentrated excessively, however, very dilute blood. This will cause all ions and blood components are in low concentration in the blood, and especially sodium.

The causes may be involved in excessive secretion of ADH are manifold:

• Growths born outside the hypothalamus but are capable of producing ADH.
• Nonmalignant lung diseases: tuberculosis, lung abscess, pneumonia, asthma, etc..
• Some drugs are capable of stimulating the production of this hormone by the hypothalamus is the case of nicotine, chlorpropamide, carbamazepine, antidepressants and certain drugs used in cancer treatment.
• Neurological diseases: Guillain-Barré syndrome, multiple sclerosis, meningitis, etc..
• Head injuries.

It is important to note that not all individuals who, for example, asthma, or taking carbamazepine, will develop this syndrome.

Symptoms

The symptoms of this disease will depend on two elements: first, sodium levels in the blood at the time of diagnosis and, secondly, the speed with which descend blood sodium levels.

Thus in cases in which the sodium reduction is slow and progressive, or in those cases in which sodium levels, although low levels are moderate (more than 130 mEq / l), the symptoms are slight or absent .

In cases in which sodium levels decrease to levels of severity (less than 120 mEq / l), or has developed rapidly, displayed neurological symptoms: agitation, confusion, irritability, decreased level of consciousness, convulsions and coma .

Diagnosis

The diagnosis passes the determination in blood sodium. Find sodium levels low or very low (hyponatremia).However, there are other causes of hyponatremia, and the syndrome of inappropriate secretion of ADH.

Therefore, to reach a correct diagnosis must rule out other causes. Thus, situations of increased blood sugar, adrenal insufficiency and hypothyroidism can cause a decrease in blood sodium. In SIADH called blood osmolarity (calculated by the levels of sodium, potassium and blood sugar) is decreased, and also there will be a very concentrated urine, with much the urine sodium excretion and urine osmolality increased (greater than of blood). Furthermore, in the SIADH characteristically no fluid retention in the feet (edema), or there is low blood pressure, no signs of dehydration.

Treatment

Treatment can be aimed at correcting the cause that caused the excess secretion of ADH, if known. For example, you should remove suspected drugs that may be involved, troubleshoot possible infections, or remove the tumor. But sometimes there is no known cause of SIADH, or can not fix the cause. Thus, in most cases the treatment is aimed at improving sodium levels and increased blood concentration (osmolality) and decrease in urine.

In these cases indicate a restriction of total fluid intake to less than 800-1000 ml per day. Can also be used low dose of furosemide (a diuretic potent characterized by removing more water than sodium in the urine and thus achieves concentrate dilute urine and blood). If, on the other hand, is not achieved with these measures can be used to correct the sodium drugs acting either ADH secretion inhibiting or blocking its action. Among these drugs stresses demeclocycline, 150 to 300 mg orally three or four times a day, or fludrocortisone, 0.05 to 0.2 mg orally twice a day.

In acute cases of rapid onset, with greatly reduced levels of sodium, and neurological disorders, should be instituted based intravenous serum sodium rich vein to raise sodium levels to levels considered safe (above 120 mEq / l). However, this treatment should be done slowly and in a hospital, because a too rapid correction of sodium levels can cause a serious condition called “central pontine myelinolysis” that can cause permanent neurological losses.

Precautions

There are no measures to prevent its occurrence. Only use controls blood in people with acute illness or trauma or brain injury.