USMLE Renal 7: Electrolyte Disturbances Explained (Sodium, Potassium, and more!)

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/ lymed Welcome to LY Med, where I go over everything you need to know for the USMLE STEP 1, with new videos every day.
Follow along with First Aid, or with my notes which can be found here: www.dropbox.co...
More renal physiology! In this video, we will discuss electrolyte disturbances. Your kidneys are incredibly important in regulating electrolytes and if you have a disturbance in the levels, you can have symptoms! We'll talk about sodium first:
Too little sodium is called hyponatremia and can be caused by loss of salt or changes in fluid. Thus we can break it down to hypovolemic, hypervolemic, and euvolemic. Common causes of hypervolemic hyponatremia is organ failure like in heart failure or kidney failure. Hypovolemic is caused by loss of fluid like in sweating, diarrhea, diuretics, or aldosterone insufficiency. Euvolemic is usually caused by too much ADH, or SIADH. Causes of SIADH include small cell carcinoma of the lung, CNS lesions and medications. Hypernatremia is from too much salt or a loss of fluid. Again, ADH plays a role. If you hae too little ADH, then you'll lose a ton of water. We call this diabetes insipidus. Now what causes this low ADH? Well CNS lesions can lead to a loss of ADH from pituitary damage. Another way you can get this is if your ADH receptors are mutated. We call this nephrogenic diabetes insipidus. How can you tell the two apart? Just give an ADH analogue like desmopressin! In central DI, it'll fix it. However, in nephrogenic DI it won't fix the problem. Instead, pharmacology that target's nephrogenic DI include thiazides and amilorides (K+ sparing diuretics). Done with sodium!
Moving on to potassium disturbances! A lot of pumps use potassium, including the Na/K ATPase pump, the H/K+ pump, and also all those potassium pumps in your kidneys! Too little potassium is called hypokalemia. This is caused by increased insulin and sympathetic activation as it activates our Na/K+ pump. Alkalosis can also cause this, as well as increase renal excretion like in hyperaldosteronism, diuretic use, vomiting etc. What are some findings of hypokalemia? Well your cells are hyperpolarized and disrupts the membrane potential of your cardiocytes! This can lead to arrhythmia and you'll see U waves on ECG.
Hyperkalemia is caused by low insulin, low sympathetic drive and acidosis. Also hypoaldosteronism (Addison's) and K sparing diuretics can cause this. Also know that cell lysis like in cancer or rhabdomyolysis or leukemia can cause this! When cells die, they release K+! What shows up symptomatically? Well you get arrhythmias here too! You get peaked T waves and prolonged QRS to the point that it looks like a sine wave! How do we treat it? We can give calcium to help stabilize the membrane.
To finish off our this talk, we'll go over some last electrolytes. We'll start magnesium. Low magnesium is often concurrent with calcium and potassium loss leading to tetany and torsades de pointes. Too much acts as a depressant, leading to loss of deep tendon reflex and cardiac arrest.
Phosphate: low leads to rickets and osteomalacia. High levels lead to renal stone and metastatic calcification.
Calcium: they help stabilize the cells. Low levels lead to unstable cells and lead to tetany and seizures. You can see this with Trousseau sign, Chvosteks sign. In high calcium it hyperstabilizes cells, leading to abdominal pain, altered mental state, and bone pain. Can lead to calcium kidney stones. Common causes of calcium disturbances include inappropriate PTH, or acid base disturbances.

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Much love, -Mike

[@bravefight7549]

05:38... ADH is not made in the pituitary gland, it is made in the paraventricular and supraoptic nuclei of the hypothalamus.

[@tiiinaacar]

Yes, its made in the hypothalamus but stored in and released from the posterior pituitary gland.

[@SweetHomeEverAfter]

thank you, yours video is amazing, helpful to cover all HY stuffs in FA

[@dr.munibakhan2049]

You’re a gem ! Thankyou for all the videos . They are life saver ❤️

[@ibrakeforbutterflies]

Thank you for taking the time to dive into the pathophysiology while also pausing and asking "wait, so what is that?" The SiADH in euvolemic hyponatremia never made sense to me until now. I just need to look up why thiazides cause hypercalcemia because I still don't get that. Thanks again

[@shaunmathew]

Hey, did you find out why?

[@ainamardhiah3940]

tq for all the recaps in the video, and you over many concepts as well. New subscriber

[@palmspirit1833]

Anyone struggling with the low volume, headphones really help.

[@pertua4luv24]

That was so helpful, THANK YOU!

[@kpa742]

Thanks!!

[@beshoymaher3468]

I want to tutor me for step 1 ?

[@olgasa6943]

Came to watch but couldn't hear you. So I stayed long enough to write this comment😌

[@thespiritof76..]

I think what your saying is happening to me.... I think my heart is shutting down from it. My feet are so swelled I can hardly stand... I have PTSD attacks at the thought of going to a hospital, and possibly dying there..

[@kristinjh]

thanks really helpful

[@Vote.for.justice]

Sir can I have hyponatremia cause frequent urination due to uti ... My body went into shock I'm peeing 30 times a day from last two weeks..pls reply

[@alexismarquez3674]

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[@reemabdullah9877]

if ADH influences the loop of henle to reabsorb some salts and urea how does that cause hyponatremia in cases of SIADH

[@palmspirit1833]

Reem Abdullah ADH mainly acts on the collecting ducts, not the loop. Because excessive ADH (as in SIADH) causes you to retain lots of water, the increased vascular pressure triggers the counter-regulatory pathways. Basically the same responses that counter the RAAS (BNP and ANP). This would cause salt and water dumping. The water dumping counters the water retention by SIADH, but the salt jumping is unopposed. Hence, euvolemic hyponatremia.

[@reemabdullah9877]

@@palmspirit1833 thank yooou so much! I struggled with this concept for the longest time!!!!

[@palmspirit1833]

@@reemabdullah9877 lol same! Renal physiology is crazy.

[@meetbrahmbhatt8495]

@@palmspirit1833 not Hypovolemic....SIADH causes Euvolemic hyponatremia

[@palmspirit1833]

@@meetbrahmbhatt8495 you're right. I'll edit right away.

[@rajendrasheregar3113]

among eLectroLytes Na.k.cL.Na: cl•: are saLThe 3rd ion of cl is conjugaTion ion site for iodine as preferable onLy iodine conjugaTion

[@ahmedrahmathulla198]

your hand writing is little bit bad

[@rajendrasheregar3113]

among eLectroLytes Na.k.cL.Na: cl•: are saLThe 3rd ion of cl is conjugaTion ion site for iodine as preferable onLy iodine conjugaTion