Lasix and Hyponatremia

[chenoaspirit, ASN, RN]

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?

[Ivanna_Nurse, BSN, RN]

Maybe the patient has some extra fluid on board?? (Dilutional hyponatremia comes to mind.) With the NaCl tabs replacing the sodium and lasix getting rid of fluid, generally the two balance each other out nicely. ~Ivanna

[chenoaspirit, ASN, RN]

It seems like the two together are going against each other. And also, the treatment didnt work.

[chenoaspirit, ASN, RN]

Also, he had no edema, no crackles in lungs.

[Valerie Salva, BSN, RN]

I know that when the body loses K+, it responds by retaining Na+ in order to maintain +/- electrolyte balance and plasma conductivity.

Also, mild dehydration helps to increase Na+ concentration in the blood- sort of the opposite of dilutional hyponatremia.

Maybe by ordering Lasix, this is what the doc was trying to initiate.

[flightnurse2b, LPN]

hmm... maybe because in pts with hyponatremia, they are usually volume depleted, causing an increase in ADH, causing the pt to retain water and concentrate urine.... ??

i dunno. still doesnt make much sense.

ETA: i would like to know the reasoning behind it as well!

[chenoaspirit, ASN, RN]

I know that when the body loses K+, it responds by retaining Na+ in order to maintain +/- electrolyte balance and plasma conductivity.

Also, mild dehydration helps to increase Na+ concentration in the blood- sort of the opposite of dilutional hyponatremia.

Maybe by ordering Lasix, this is what the doc was trying to initiate.

Well, the dehydration makes sense, but he used a diuretic that takes away sodium rather than one that doesnt, such as Mannitol. Ive asked so many people at work, they all agree with me. It doesnt matter, I dont guess, but I just want to understand. Im one of those type people, lol. BTW, this was a resident.

[CRNA2007]

what was the serum sodium? I agree with the dilutional statement if that is what the doctor was referencing. I have also seen physicians give small boluses of 3% saline through and IV as well to increase the serum sodium concentration.

[chenoaspirit, ASN, RN]

He was on NS at 150 ml/hr with a fluid restriction of 1500/day. His IV was later saline locked. His sodium was 125. I wondered why he didnt order hypertonic IV solution.

[Valerie Salva, BSN, RN]

A while back, I was reading a list of the top twenty most dangerous drugs and hypertonic saline solution was on the list. Apparently, it increases serum sodium too rapidly, which can lead to a lot of problems.

[SweetTeaRN, BSN, RN]

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.

[Virgo_RN, BSN, RN]

From Pharmacology for Nursing Care, 6th Edition:

In order to promote excretion of water, diuretics must compromise the normal operation of the kidney. By doing so, diuretics can cause hypovolemia (from excessive fluid loss), acid-base imbalance, and disturbance of electrolyte levels. These adverse effects can be minimized by using short-acting diuretics and by timing drug administration such that the kidney is allowed to operate in a drug-free manner between periods of diuresis. Both measures will give the kidney periodic opportunities to readjust the ECF so as to compensate for any undesired alterations produced under the influence of diuretics.