UPDATE: Bret Michaels has a new setback

Singer Bret Michaels has suffered yet another setback. According to his Facebook page: ” Test results indicate a setback in Bret Michaels condition a side effect from the brain hemorrhage called hyponatremia- a lack of sodium in the body which leads to seizures. ” As of this time, Michaels has not actually had any seizures, but the potential is there.

Hyponatremia is the medical term for a low amount of sodium in the blood. Sodium is an extremely important element in the body- being an essential electrolyte which aids in a number of vital bodily processes. Many heart and nerve functions, muscle control and coordination, and the body’s ability to absorb fluids all depend on a healthy balance of electrolytes. The most common electrolytes found in the human body are sodium, potassium, magnesium, chloride and calcium. Normal blood sodium is 135-145 mEq/L.

When the amount of sodium in fluids outside cells drops, water moves into the cells to balance the levels. This causes the cells to swell with too much water. Although most cells can handle this swelling, brain cells cannot, because the skull bones confine them. Brain swelling causes most of the symptoms of hyponatremia.

In hyponatremia, the imbalance of water to salt is caused by one of three conditions:

* Normal volume (euvolemic) hyponatremia — total body water increases, but the sodium content remains the same. This is commonly due to chronic health conditions, cancer or certain medications, such as diuretics.
* High volume (hypervolemic) hyponatremia — both sodium and water content in the body increase, but water gain is greater. This is commonly the result of kidney failure, heart failure or liver failure.
* Low volume (hypovolemic) hyponatremia — water and sodium are both lost from the body, but the sodium loss is greater. This is commonly caused by heat exhaustion, or large blood loss.

Causes of hyponatremia include:

• Burns
• Congestive heart failure
• Diarrhea
• Use of medications called diuretics (“water pills”)
• Kidney diseases
• Liver cirrhosis
• Sweating-especially with replacement by electrolyte free water
• Vomiting
• Syndrome of inappropriate antidiuretic hormone secretion (SIADH)

In this last cause, SIADH, high levels of the anti-diuretic hormone (ADH) are produced, causing the body to retain water instead of excreting it in the urine, causing low blood sodium by dilution. SIADH can be a consequence of brain disorders, including subarachnoid hemorrhage. According to an article in J. Neuroscience Nursing (see casebook below) “Hyponatremia is seen in 10%-40% of the patients with subarachnoid hemorrhage (SAH) admitted to the neuro critical care unit.” Although some controversy exists as to what the cause is, many believe that SIADH plays a major role in this observation.

Symptoms of hyponatremia include fever, headache, nausea and vomiting, muscle cramps, weakness, and confusion occur when serum sodium values are 115-120 mEq/L. Stupor, seizures and coma are more typically associated with serum sodium values of less than 110 mEq/L.

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