15 Na Disorders
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- both results lead to brain symptoms
Hyponatremia
![](https://photos.thisispiggy.com/file/wikiFiles/EKPD9ln.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/HCOKrqd.jpg)
Plasma osmolality
![](https://photos.thisispiggy.com/file/wikiFiles/dT9xJS0.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/ywwdcpW.jpg)
- albumin minor contributor, not in equation, more important for oncotic pressure
![](https://photos.thisispiggy.com/file/wikiFiles/SYcpruJ.jpg)
- 1.6 meq/L decrease in Na for every 100mg/dL increase in glucose
![](https://photos.thisispiggy.com/file/wikiFiles/FhchlVz.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/BsGG3Sm.jpg)
- substances interfere with Na measurement
- triglycerides
- post-TURP
![](https://photos.thisispiggy.com/file/wikiFiles/FhchlVz.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/FhchlVz.jpg)
- low osmolality: unknown cause
![](https://photos.thisispiggy.com/file/wikiFiles/oQ05t49.jpg)
- Low usine osm: post TURP, beer potomonia
![](http://www.uworld.com/media/L7027.jpg)
![](http://www.uworld.com/media/L21379.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/image-20190821080606702.png)
Urinary Sodium
![](https://photos.thisispiggy.com/file/wikiFiles/oRhYfaA.jpg)
- in reality, no normal levels because varies
- intake equals excretion
- urine Na < 10: extrarenal including CHF, cirrhosis, nephrotic syndrome
- urine > 20: renal including AKI, CKD
- Patients with SIADH are typically euvolemic; therefore, urine sodium concentration is typically elevated (>40 mEq/L), unlike in patients with hypovolemia.
Urinary Osmolality
![](https://photos.thisispiggy.com/file/wikiFiles/7hjpD7U.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/yRg9q0S.jpg)
- ADH controls above 3 tests
![](https://photos.thisispiggy.com/file/wikiFiles/DVUeuaJ.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/P6mWLFw.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/H5i25Tk.jpg)
- if body responding appropirately
- urinary Na may vary with dietary intake
![](https://photos.thisispiggy.com/file/wikiFiles/xEghEa6.jpg)
Causes
![](https://photos.thisispiggy.com/file/wikiFiles/kUSDqvG.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/oQ05t49.jpg)
HF
![](https://photos.thisispiggy.com/file/wikiFiles/Akr6yrz.jpg)
- high Uosm because ADH high
Renal Failure
![](https://photos.thisispiggy.com/file/wikiFiles/LIiygLm.jpg)
- renal failure: concentrated urine even at baseline. Can't excrete water
Diuretics
![](https://photos.thisispiggy.com/file/wikiFiles/ysYs6OV.jpg)
- hyponatremia common with thiazides
![](https://photos.thisispiggy.com/file/wikiFiles/L9i29sx.jpg)
loop diuretic effect:
- decreased Na absorption, increased osm at CD, decreased Na/water absorption
- interstitial high osm eliminated, lower driving force to remove water
- result: very hard to reabsorb water and become hyponatremic
thiazide:
- Na blocked, increased osm at CD, decreased water/Na absorption
- medullary osm intact: continue to maintain ability to absorb free water
- result: excrete Na but absorb water = hyponatremia
![](https://photos.thisispiggy.com/file/wikiFiles/lggfjtS.jpg)
ADH and SIADH
![](https://photos.thisispiggy.com/file/wikiFiles/sLFDEwd.jpg)
- reason why athletes drink Gatorade and not water
![](https://photos.thisispiggy.com/file/wikiFiles/rYNsnR1.jpg)
- hypothyroidism: high ADH with low thyroid
![](https://photos.thisispiggy.com/file/wikiFiles/ZCV145Z.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/9qgOXI1.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/qpR2aqE.jpg)
- stroke, brain bleeds, tumor
- any kind of pulmonary diseases, small cell lung cancer
![](https://i.imgur.com/bizBioe.jpg)
- Inappropriately wet head: cyclophosphamide can cause hyponatremia due to SIADH
![](https://photos.thisispiggy.com/file/wikiFiles/GT1zADj.jpg)
- clinical euvolemia: absence of signs
![](https://photos.thisispiggy.com/file/wikiFiles/image-20190821080325489.png)
![](https://photos.thisispiggy.com/file/wikiFiles/0owQPYj.jpg)
Psychogenic
![](https://photos.thisispiggy.com/file/wikiFiles/kV0jTLc.jpg)
Diets
![](https://photos.thisispiggy.com/file/wikiFiles/KSQcDxB.jpg)
- common theme: little Na ingestion
- kidney must maintain minimum osm
![](https://photos.thisispiggy.com/file/wikiFiles/2HcQd19.jpg)
- pt on restricted diet can only excrete 10 water
![](https://photos.thisispiggy.com/file/wikiFiles/TRAmf1B.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/GTGuQfX.jpg)
Summary
Volume and Osm
![](https://photos.thisispiggy.com/file/wikiFiles/sV6xPHh.jpg)
- hypervolemic: physical exam signs. Use loop diuretics and not thiazide
![](https://photos.thisispiggy.com/file/wikiFiles/oTmIvJa.jpg)
- Mostly hormone derangements
- low Uosm: kidney response normal
![](https://photos.thisispiggy.com/file/wikiFiles/WmSWYmw.jpg)
- measure UNa to differentiate
- hypovolemic: Low sodium, low water, but a lot less Na
- diuretics, adrenal insufficiency (acidosis, hyperkalemia), GI loss, 3rd spacing (pancreatitis)
- Treat with NS
ADH and Osm
![](https://photos.thisispiggy.com/file/wikiFiles/aDg8sqd.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/81tDIMR.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/XPDRTSL.jpg)
Treatment
![](https://photos.thisispiggy.com/file/wikiFiles/iWQbVe1.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/sHna2qG.jpg)
- acute hyponatremia: correct as fast as can (e.g. surgery causes low Na)
- chronic hyponatremia: correct slow
- high risk: alcoholics, liver disease, malnutritioned, hypokalemia
- 10 meq correction 1st day
Hypernatremia
![](https://photos.thisispiggy.com/file/wikiFiles/oKc0dqj.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/Fd8V6wb.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/vbE8suI.jpg)
DI
![](https://photos.thisispiggy.com/file/wikiFiles/7CxnCR8.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/xHZioBo.jpg)
- hypernatremia happen in central lesion
![](https://photos.thisispiggy.com/file/wikiFiles/Ceuoq8t.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/NrR1UHJ.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/PgmeBfC.jpg)
![](https://photos.thisispiggy.com/file/wikiFiles/zLPaE2z.jpg)
- thiazide, endomethacin (NSAID), amiloride
Treatment
- calculate free water deficit
$$
Water\ deficit = \frac{[Na]-140}{140} \times TBW
$$