Did you check out the latest SKG case? Read all about it in this awesome and fun thread by @nepherson
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⚡️Taking inspiration, here’s a 🧵on the complications of hyponatremia
#NSMC #Tweetorial @TheSkeletonKG
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👇
⚡️Taking inspiration, here’s a 🧵on the complications of hyponatremia
#NSMC #Tweetorial @TheSkeletonKG
👇
1/22
But before we start - I have two words for you!
☝️OSMOLALITY and
✌️TONICITY
Are they the same or are they not?
🤔
But before we start - I have two words for you!
☝️OSMOLALITY and
✌️TONICITY
Are they the same or are they not?
🤔
Are OSMOLALITY and TONICITY the same thing?
2/22
Plasma Osmola - R - ity ➡️
Concentration of osmoles (effective ➕ ineffective solutes) per unit VOLUME of plasma water
Plasma Osmola - L - lity ➡️
Concentration of osmoles (effective ➕ ineffective) per unit MASS of plasma water
Plasma Osmola - R - ity ➡️
Concentration of osmoles (effective ➕ ineffective solutes) per unit VOLUME of plasma water
Plasma Osmola - L - lity ➡️
Concentration of osmoles (effective ➕ ineffective) per unit MASS of plasma water
3/22
Plasma TONICITY ➡️
Concentration of only EFFECTIVE osmoles, setting up the osmotic gradient
Confused 🥴 already?
Plasma TONICITY ➡️
Concentration of only EFFECTIVE osmoles, setting up the osmotic gradient
Confused 🥴 already?
4/22
EFFECTIVE OSMOLES ➡️ Solutes that CANNOT 🚫pass through cell membranes without active transporters
Eg: Na
INEFFECTIVE OSMOLES ➡️ Solutes that can ✅freely diffuse across membranes
Eg: Urea
✔️Both can influence the movement of water
EFFECTIVE OSMOLES ➡️ Solutes that CANNOT 🚫pass through cell membranes without active transporters
Eg: Na
INEFFECTIVE OSMOLES ➡️ Solutes that can ✅freely diffuse across membranes
Eg: Urea
✔️Both can influence the movement of water
5/22
Ineffective osmoles diffuse🔄 across cells to maintain a similar level ⚖️ on both sides and so cannot set up a significant gradient
But If ECF Na is ⏬ low, osmosis drives water 💧 inside the cells↩️
So only effective osmoles can generate an osmotic gradient!😯
Ineffective osmoles diffuse🔄 across cells to maintain a similar level ⚖️ on both sides and so cannot set up a significant gradient
But If ECF Na is ⏬ low, osmosis drives water 💧 inside the cells↩️
So only effective osmoles can generate an osmotic gradient!😯
6/22
Simply put,
👉Tonicity = EFFECTIVE osmolality
Na➡️contributes to osmolality AND tonicity
Urea➡️contributes ONLY to osmolality
Simply put,
👉Tonicity = EFFECTIVE osmolality
Na➡️contributes to osmolality AND tonicity
Urea➡️contributes ONLY to osmolality
7/22
Movement🔄 of 💧 across cells would surely cause changes in cell volume
⏬ECF Na➡️cell swells🎈
⏫ECF Na➡️cell shrinks🗯️
Disorders of Na are, in fact, disorders of water!
Check out @amyaimei’s brilliant thread for more insight 👇
Movement🔄 of 💧 across cells would surely cause changes in cell volume
⏬ECF Na➡️cell swells🎈
⏫ECF Na➡️cell shrinks🗯️
Disorders of Na are, in fact, disorders of water!
Check out @amyaimei’s brilliant thread for more insight 👇
8/22
The body's cells float in a ‘pool’ of water, with Na and K (and other electrolytes) added in
ncbi.nlm.nih.gov/pubmed/20889809
The body's cells float in a ‘pool’ of water, with Na and K (and other electrolytes) added in
ncbi.nlm.nih.gov/pubmed/20889809
9/22
In hyponatremia, the ECF Na is low 📉
Possible causes (which have eluded physicians since the beginning of time!) include 👇
[Source - Comprehensive Clinical Nephrology, sixth edition]
In hyponatremia, the ECF Na is low 📉
Possible causes (which have eluded physicians since the beginning of time!) include 👇
[Source - Comprehensive Clinical Nephrology, sixth edition]
10/22
So you can have one of two conditions:
(Excluding pseudo-hyponatremia)
👉You are losing Na
👉You are a bag of water
In any case, your cells are in a hypotonic medium
They get an alert message -
🚨
So you can have one of two conditions:
(Excluding pseudo-hyponatremia)
👉You are losing Na
👉You are a bag of water
In any case, your cells are in a hypotonic medium
They get an alert message -
🚨
11/22
Our little heroes 🦸 - the cells - decide to help out
“Ok plasma, we are in this together! Give us some extra water!”
So, water enters the cells, which now swell up🎈
Our little heroes 🦸 - the cells - decide to help out
“Ok plasma, we are in this together! Give us some extra water!”
So, water enters the cells, which now swell up🎈
12/22
In the brain 🧠, astrocytes swell up within the confines of the skull 💀 and the pressure within, or the intracranial pressure rises⏫
nejm.org/doi/full/10.10…
In the brain 🧠, astrocytes swell up within the confines of the skull 💀 and the pressure within, or the intracranial pressure rises⏫
nejm.org/doi/full/10.10…
13/22
This explains why many of the classical clinical manifestations of hyponatremia are neurological in nature
👇
This explains why many of the classical clinical manifestations of hyponatremia are neurological in nature
👇
14/22
In acute hyponatremia (<48 hours), 🧠edema may progress so fast ⚡️that patients deteriorate rapidly and may even die due to brain herniation! ☠️
In acute hyponatremia (<48 hours), 🧠edema may progress so fast ⚡️that patients deteriorate rapidly and may even die due to brain herniation! ☠️
15/22
In chronic hyponatremia (>48 hours), the 🧠 adapts to counteract the swelling
How so? 👇
👉First, cells lose Na, K and Cl (Rapid🐇adaptation) - within minutes!
👉Then, they throw out organic osmolytes like glutamate (Slow🐢adaptation) - within hours to days
In chronic hyponatremia (>48 hours), the 🧠 adapts to counteract the swelling
How so? 👇
👉First, cells lose Na, K and Cl (Rapid🐇adaptation) - within minutes!
👉Then, they throw out organic osmolytes like glutamate (Slow🐢adaptation) - within hours to days
16/22
However, this comes at a considerable cost!
1⃣ Loss of excitatory neurotransmitters like glutamate can cause gait disturbances, confusion and seizures😵
2⃣ Remember, the astrocytes lost all their osmolytes in an attempt to maintain brain volume😓
However, this comes at a considerable cost!
1⃣ Loss of excitatory neurotransmitters like glutamate can cause gait disturbances, confusion and seizures😵
2⃣ Remember, the astrocytes lost all their osmolytes in an attempt to maintain brain volume😓
17/22
If Na is corrected too rapidly, plasma tonicity acutely increases 📈
To prevent 💧 from rushing out, cells must regain osmolytes!
But this takes hours to days⏳
So now there is nothing to gain but everything to lose⚠️
If Na is corrected too rapidly, plasma tonicity acutely increases 📈
To prevent 💧 from rushing out, cells must regain osmolytes!
But this takes hours to days⏳
So now there is nothing to gain but everything to lose⚠️
18/22
Astrocytes undergo apoptosis ☠️leading to demyelination of white matter 🧠 - what we all know as Osmotic Demyelination Syndrome (ODS)
Astrocytes undergo apoptosis ☠️leading to demyelination of white matter 🧠 - what we all know as Osmotic Demyelination Syndrome (ODS)
19/22
To quote Dr Sterns - the reuptake of organic osmolytes after correction of hyponatremia is slower than is the loss of organic osmolytes during the adaptation to hyponatremia
ncbi.nlm.nih.gov/pubmed/?term=1…
To quote Dr Sterns - the reuptake of organic osmolytes after correction of hyponatremia is slower than is the loss of organic osmolytes during the adaptation to hyponatremia
ncbi.nlm.nih.gov/pubmed/?term=1…
20/22
Never correct chronic hyponatremia too fast
👉US guidelines 🇺🇸amjmed.com/article/S0002-…
👉EU guidelines 🇪🇺eje.bioscientifica.com/view/journals/…
Throwback to #Nephmadness 2018 👇ajkdblog.org/2018/03/15/nep…
Never correct chronic hyponatremia too fast
👉US guidelines 🇺🇸amjmed.com/article/S0002-…
👉EU guidelines 🇪🇺eje.bioscientifica.com/view/journals/…
Throwback to #Nephmadness 2018 👇ajkdblog.org/2018/03/15/nep…
21/22
Summary,
👇
1⃣Tonicity = EFFECTIVE osmolality
2⃣Na disorders are 💧 disorders
3⃣Hyponatremia causes💧to move in cells ➡️rise in ICP➡️classical🧠manifestations
4⃣Cells adapt🌀to mitigate volume changes
5⃣Rapid correction in can cause ODS🚫
Summary,
👇
1⃣Tonicity = EFFECTIVE osmolality
2⃣Na disorders are 💧 disorders
3⃣Hyponatremia causes💧to move in cells ➡️rise in ICP➡️classical🧠manifestations
4⃣Cells adapt🌀to mitigate volume changes
5⃣Rapid correction in can cause ODS🚫
22/22
Incidentally, chronic hyponatremia has also been proposed as a risk factor for 🦴osteoporosis and fractures #⃣ because the skeleton is a Na reservoir and hyponatremia may promote bone loss through osteoclastic activity
Incidentally, chronic hyponatremia has also been proposed as a risk factor for 🦴osteoporosis and fractures #⃣ because the skeleton is a Na reservoir and hyponatremia may promote bone loss through osteoclastic activity
Shout out to @hswapnil @Nephro_Sparks @kidney_boy @amyaimei @SaynaNorouzi, @Vernisartan @ Ryann Coffman, and everyone @TheSkeletonKG ! Thank you for this opportunity and your invaluable suggestions. You guys rock! 🤘
