Jacked Up Sodium

allnurses Guide · Dec 31, 2009

Normal saline is isotonic, it doesn't really increase sodium a whole lot, nor does it really cause fluid shifts. For a Na+ as low was 119-120, you definitely wanted the fluid restriction, slow replacement with 3% and/or diuresis if she's fluid overloaded (?from heart failure?). I'd want to know if it's dilutional or truly that low, then I'd want to know why.

I would probably want a BNP! Then again, I am a cardiac nurse so I can't help seeing heart failure everywhere...

GilaRRT · Dec 31, 2009

My question is....How the heck could her sodium get lower after a bolus and being on regular fluids for 6-7 hours? At first I thought the lab screwed up, especially since she wasn't confused (She was 85). This has been naggin me all weekend.

Lets work this out:

Look at a litre of 0.9 % saline. You should expect 154 mEq of sodium ion per litre of normal saline. (Remember the formula of molarity = moles/litres & 1000 mEq = 1 Eq ) So, you have 0.154 Eq/litre. You gave 500 ml of NS followed by 100 ml/hr for 6 hours. So, we can say the patient received 1,100 ml of NS. This roughly equals, 0.154 Eq + 0.0924 Eq = 0.2464 Eq. Not exactly allot of sodium ion. This is especially true because whatever caused the hyponatremia was not corrected. Therefore, I would not suspect a major change in serum sodium.

Finding the cause should be paramount and potentially difficult as sodium derangements are the most common electrolyte imbalances encountered.

In addition, a multitude of medications can cause or exacerbate hyponatremia. A non-inclusive list from eMedicine:

"cetazolamide, amiloride, amphotericin, aripiprazole, atovaquone, thiazide diuretics, amiodarone, basiliximab, angiotensin II receptor blockers, angiotensin-converting enzyme inhibitors, bromocriptine, carbamazepine, carboplatin, carvedilol, celecoxib, cyclophosphamide, clofibrate, desmopressin, donepezil, duloxetine, eplerenone, gabapentin, haloperidol, heparin, hydroxyurea, indapamide, indomethacin, ketorolac, levetiracetam, loop diuretics, lorcainide, mirtazapine, mitoxantrone, nimodipine, oxcarbazepine, opiates, oxytocin, pimozide, propafenone, proton pump inhibitors, quetiapine, sirolimus, ticlopidine, tolterodine, vincristine, selective serotonin reuptake inhibitors, sulfonylureas, trazodone, tolbutamide, venlafaxine, zalcitabine, and zonisamide."

RNKPCE · Dec 31, 2009

Is BMP- basic Metabolic panel?

If so that is very close to BNP( brain natriuretic peptide ) which shows if your heart is working harder than normal as would happen in CHF.

AnnieNHRN · Dec 31, 2009

Did they check her for Syndrome of Inappropriate Antidiuretic Hormone Hypersecretion (SIADH)? That can cause low sodium.

chenoaspirit, ASN, RN · Dec 31, 2009

Gila, I bet you are a chemistry whiz! I cant even remember what moles are, much less the formula. Im impressed! However I do understand how 0.9 NS wouldnt increase Na+ and so forth. But I wish I could remember what I learned in my chemistry class years ago.

Virgo_RN, BSN, RN · Dec 31, 2009

My question is....How the heck could her sodium get lower after a bolus and being on regular fluids for 6-7 hours? At first I thought the lab screwed up, especially since she wasn't confused (She was 85). This has been naggin me all weekend.

500ccs of NS isn't going to make a whole heck of a lot of difference in her serum sodium level as far as increasing it. The drop of one point in 6 hours was probably a combination of the IVF and a reflection of the trend she was already on. She could be chronically hyponatremic at baseline, and/or the drop in serum sodium was so gradual that she was able to compensate. Gradual electrolyte shifts are much easier for the body to adjust for than sudden ones. A lot of folks on diuretics and ACE-Is are chronically hyponatremic, but the hyponatremia is stable and not severe, and they compensate for it, so it's not concerning, until something happens to throw off their compensatory mechanisms.

Virgo_RN, BSN, RN · Dec 31, 2009

Is BMP- basic Metabolic panel?

Yes.

If so that is very close to BNP( brain natriuretic peptide ) which shows if your heart is working harder than normal as would happen in CHF.

Yes, it sounds close, so if the doctor really wanted a BNP (a measure of left ventricular stretch related to overfilling), it would be easy to think s/he said "BMP". Some docs call it a "Chem 7". We call it either a "Basic" or a "Comp" to avoid the confusion.

PostOpPrincess, BSN, RN · Dec 31, 2009

She is 85.

She has to be fully worked up for all sorts of disease processes especially brain and kidneys, including her PMHX w/meds.

I'm still not over the statement where they were ABOUT to release her until she passed out again...and the BMP hadn't even come back?

Am I reading that correctly?

Virgo_RN, BSN, RN · Dec 31, 2009

I'm still not over the statement where they were ABOUT to release her until she passed out again...and the BMP hadn't even come back?
Am I reading that correctly?

That does seem odd....

GilaRRT · Dec 31, 2009

Gila, I bet you are a chemistry whiz! I cant even remember what moles are, much less the formula. Im impressed! However I do understand how 0.9 NS wouldnt increase Na+ and so forth. But I wish I could remember what I learned in my chemistry class years ago.

Not really. I have some basic gen chem knowledge, but that is about the limit of my chemistry prowess.

A mole is actually a number, Avogadro's number to be exact. In essence, Avogadro's number is 6.02 * 10 (23). It applies to many chemistry concepts. The atomic weight of an atom is based on this number. An incredible relationship exists. For example, hydrogen has an average weight of 1. This means that 6.02 * 10 (23) atoms of hydrogen will weigh about 1 gram. Helium is 2, Lithium is 3, and so on. So, if I have a mole of a substance, I can calculate weights and numbers of atoms with a very high degree of accuracy.

This relationship is where the concept of an equivalent comes from. An equivalent of a substance is a way of integrating charge and moles. For example, I have a mole of sodium ions (sodium stripped of enough electrons to meet the octet rule, another concept) in a litre of water. So, to find the moles of an ion, we use the formula; moles*charge=X. In the case of sodium, it takes on a charge of +1 due to the loss of an electron. So, 1 * mole (1) = molarity of 1 mole per litre. This standard of 1 mole per litre is also known as a equivalent Eq or Moles * Charge. Therefore, I have 1 equivalent of sodium in a litre of solution.

You can see this system can tell us how much of an electrolyte we give somebody with high precision and accuracy. In fact, using some dimensional analysis, I can calculate the number of atoms and the weight of the sodium dissolved in a litre of 0.9% saline. A litre of normal saline contains 3.54 grams of sodium. I can theoretically calculate this with any electrolyte (ion solution).

Virgo_RN, BSN, RN · Dec 31, 2009

Mmmm, avocados!