Lasix and Hyponatremia

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Today I had a patient who was hyponatremic. The doc ordered Salt tablet and Lasix to increase sodium level. That doesnt make sense to me. Lasix inhibits sodium reabsorption in the kidney. Wherever sodium goes, water follows, hence the increase in urine output when taking Lasix... am I right?. This treatment didnt increase the sodium level. Am I looking at this wrong? Ive looked it up and Ive read that a diuretic such as Mannitol can increase serum sodium, but that lasix can actually CAUSE hyponatremia. I asked the doctor to explain this to me today and he was explaining exactly as I would, but he was interpreting that decreasing sodium reabsorption was keeping it in the blood. He just didnt make any sense at all. Wouldnt lasix decrease serum sodium?

i assume this was used in a case of hypervolemic hyponatremia?

taken from an emedicine.com article:

lasix (furosemide)

high-ceiling diuretic with a prompt onset of action that acts upon ascending limb of loop of henle to inhibit sodium/potassium/chloride cotransport system, thereby increasing solute delivery to distal renal tubules, which acts to increase free water excretion. this can lead to increased aldosterone production, resulting in increased sodium absorption. absorbed readily from the gi tract and also available in parenteral preparations. diuresis begins 30-60 min with oral vs 5 min with iv administration. potassium excretion also is increased. elderly patients may have greater sensitivity to effects of furosemide.

exactly.

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The salts were given to pull fluid from the intracellular space. This pull decreases cellular swelling attributed with hyponatremia and increases extracellular fluid volume.

The lasix was given to excrete the excess fluid that is attributing to dilutional hyponatremia. Once the fluid is expelled, the ratio of water to sodium is no longer so imbalanced and the dilutional hyponatremia subsides as the ratio normalizes.

The salts will also substitute additional sodium excreted with diuresis, preventing further hyponatremia.

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Specializes in ICU.

Yes, a sodium of 125 is low, but sodium is something you never replace quickly, like you would potassium. I was told by a doc, that over a few days is sufficient to get sodium levels back to normal. Pt's can get "locked in" if the sodium is replaced too fast. So they are awake, but paralized and cant move or do anything. Google it and you can read more about it. If the patients otherwise appears fine with a low sodium, and the doc wants you to give hypertonic saline....I would question it. Hypertonic saline in not something you give lightly.

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Specializes in Med-Surg/Tele, ER.
Yes, a sodium of 125 is low, but sodium is something you never replace quickly, like you would potassium. I was told by a doc, that over a few days is sufficient to get sodium levels back to normal. Pt's can get "locked in" if the sodium is replaced too fast. So they are awake, but paralized and cant move or do anything. Google it and you can read more about it. If the patients otherwise appears fine with a low sodium, and the doc wants you to give hypertonic saline....I would question it. Hypertonic saline in not something you give lightly.

Thanks for that, I just learned something new. :nurse:

Excerpt from an article on hyponatremia:

Too rapid correction of serum sodium can cause central pontine myelinolysis (also known as osmotic demyelination syndrome). This is caused by large shifts of intracellular water occurring outside the brainstem as well as in the pons. It is always associated with rapid correction to normal levels (therefore stop at 120mmol/l and allow more gradual correction subsequently). Symptoms occur 2-4 days later, typically with quadriplegia and pseudobulbar palsy but it can take the form of mutism with paralysis ('locked in' syndrome).

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Good thread. We're all learning!

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Specializes in Infusion Nursing, Home Health Infusion.

I am taking the CRNI test tomorrow and just happened to be reviewing the fluid and electrolyte section. Hyponatremia can occur b/c of a net gain of water or a loss of sodium-rich fluids that are replaced by water.If there is excessive ECF volume a treatment option is to give diuretics. The pts Na was low so he was replacing that with the salt tablets and getting rid of the excessive ECF fluid with the Lasix. I will post tomorrow a bit about the use of 3% and 5% sodium chloride and the safe administration of these products b/c I am still reviewing Hope this helps

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Lasix does cause sodium loss but the water loss is greater which is the purpose for it's use. Water restriction is used as prevention/treatment in hyponatremia w/ hypervolemia/dilute urine. This link briefly describes the causes of hyponatremia and the different approaches to treating it and explains that more water is shed than NA+ w/ Lasix use. Lasix shouldn't be given in cases of hypovolemia. I'm curious if this Dr. or others routinely check for hypoglycemia, Addison's etc... as a possible cause or just treat the Low Na+.

http://www.uwo.ca/cns/resident/pocketbook/medicine/kidney/hyponatremia.html

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