HYPONATREMIA : RISK FACTORS , CAUSES, INVESTIGATIONS ,COMPLICATIONS & MANAGEMENT

HYPONATREMIA : RISK FACTORS , CAUSES, INVESTIGATIONS ,COMPLICATIONS & MANAGEMENT

RISK FACTORS OF HYPONATREMIA

The following factors may increase your risk of hyponatremia:

Age. Older adults may have more contributing factors for hyponatremia, including age-related changes, taking certain medications and a greater likelihood of developing a chronic disease that alters the body's sodium balance.

Certain drugs. Medications that increase your risk of hyponatremia include thiazide diuretics as well as some antidepressants and pain medications. In addition, the recreational drug Ecstasy has been linked to fatal cases of hyponatremia.

Conditions that decrease your body's water excretion. Medical conditions that may increase your risk of hyponatremia include kidney disease, syndrome of inappropriate anti-diuretic hormone (SIADH) and heart failure, among others.

Intensive physical activities. People who drink too much water while taking part in marathons, ultramarathons, triathlons and other long-distance, high-intensity activities are at an increased risk of hyponatremia.

SIADH

SYNDROME OF INAPPROPRIATE ADH SECRETION

Syndrome of inappropriate antidiuretic hormone secretion occurs when excessive levels of antidiuretic hormones (hormones that help the kidneys, and body, conserve the correct amount of water) are produced. The syndrome causes the body to retain water and certain levels of electrolytes in the blood to fall (such as sodium).

CAUSES OF SIADH

SYNDROME OF INAPPROPRIATE ADH SECRETION

SIADH tends to occur in people with heart failure or people with a diseased hypothalamus (the part of the brain that works directly with the pituitary gland to produce hormones). In other cases, a certain cancer (elsewhere in the body) may produce the antidiuretic hormone, especially certain lung cancers. Other causes may include the following:

Meningitis (inflammation of the meninges, the membranes that cover the brain and spinal cord)

CAUSES OF SIADH

SYNDROME OF INAPPROPRIATE ADH SECRETION

Encephalitis (inflammation of the brain)

Brain tumors

Psychosis

Lung diseases

Head trauma

Guillain-Barré syndrome (a reversible condition that affects the nerves in the body. GBS can result in muscle weakness, pain, and even temporary paralysis of the facial, chest, and leg muscles. Paralysis of the chest muscles can lead to breathing problems.)

Certain medications

Damage to the hypothalamus or pituitary gland during surgery

Thyroid or parathyroid hormone deficiencies

HIV

Hereditary causes

INVESTIGATIONS FOR DETECTING CAUSE OF HYPONATREMIA

URINARY SODIUM CONCENTRATION is useful for disinguishing between renal and extrarenal hypovolemic hyponatremia and hypervolemic hyponatremia.

PAIRED URINE AND PLASMA OSMOLALITIES  should be sent to exclude possibilty of SIADH.

CT Head to exclude any sub dural haematoma / head injury to exclude SIADH as a cause of hyponatremia.

COMPLICATIONS OF HYPONATREMIA

In chronic hyponatremia, sodium levels drop gradually over 48 hours or longer — and symptoms and complications are typically more moderate.

In acute hyponatremia, sodium levels drop rapidly — resulting in potentially dangerous effects, such as rapid brain swelling, which can result in a coma and death.

Premenopausal women appear to be at the greatest risk of hyponatremia-related brain damage. This may be related to the effect of women's sex hormones on the body's ability to balance sodium levels.

PREVENTION OF HYPONATREMIA

Treat associated conditions. Getting treatment for conditions that contribute to hyponatremia, such as adrenal gland insufficiency, can help prevent low blood sodium.

Educate yourself. If you have a medical condition that increases your risk of hyponatremia or you take diuretic medications, be aware of the signs and symptoms of low blood sodium. Always talk with your doctor about the risks of a new medication.

Take precautions during high-intensity activities. Athletes should drink only as much fluid as they lose due to sweating during a race. Thirst is generally a good guide to how much water or other fluids you need.

MANAGEMENT OF HYPONATREMIA

Hyponatremia treatment is aimed at addressing the underlying cause, if possible.

If you have moderate, chronic hyponatremia due to your diet, diuretics or drinking too much water, your doctor may recommend temporarily cutting back on fluids. He or she may also suggest adjusting your diuretic use to increase the level of sodium in your blood.

If you have severe, acute hyponatremia, you'll need more-aggressive treatment. Options include:

TREATMENT OF HYPONATREMIA

Intravenous fluids. Your doctor may recommend IV sodium solution to slowly raise the sodium levels in your blood. This requires a stay in the hospital for frequent monitoring of sodium levels as too rapid of a correction is dangerous.

Medications. You may take medications to manage the signs and symptoms of hyponatremia, such as headaches, nausea and seizures.

1.8 % saline infused at rate of ( 1.7 * patients weight in Kg) ml/hr or 3% saline infused at rate of (1.0 * pts weight in Kg )/ml/hr will increase serum sodium concentration by 1 mmol/hour.

Aim in early phases is to increase serum sodium concentration by  1 mmol/hour  but no more than  15 – 20 mmol/hour over 48 hour.

TREATMENT OF SIADH

Specific treatment for SIADH will be determined by your doctor based on:

Your age, overall health, and medical history

Extent of the disease

Your tolerance for specific medications, procedures, or therapies

Expectations for the course of the disease

The most commonly prescribed treatment for SIADH is fluid and water restriction. If the condition is chronic, fluid restriction may need to be permanent. Treatment may also include:

Certain medications that inhibit the action of ADH (also called vasopressin)

Surgical removal of a tumor that is producing ADH

Other medicines to help regulate body fluid volume