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Old 02-24-2012
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Post DKA???

A 15yr old is brought to the emergency department by his mother because of confusion.He has increased thirst and drinks several liters of water every day.physical examination shows fruits odour in his breath.Which of the following is most likely present in this patient ?
1) cellular potassium depletion
2)hyperphosphatemia
3)hypokalemia
4)positive potassium balance
5)hypernatremia
6)positive sodium balance
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Old 02-24-2012
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A. intracelular potassium depletion.

Patient has Metabolic Acidosis, lots of hydrogen, when this happens H is shifted inside the cell and potassium outside the cell.
That's why you have to check and add K when you add insulin, because insulin will shift K inside the cell again, and you'll have a serious hypokalemia.
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but why cant the answer be positive K balance?
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Old 02-24-2012
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DKA makes Potassium leave the cell,
Insulin pumps potassium into the cell.

A.
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Old 02-24-2012
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Quote:
Originally Posted by usmlemydream View Post
but why cant the answer be positive K balance?
Because, the shift of Hydrogen for K, that shift depleted the K levels inside the cell, now all the K is outside the cell. If you measure in that moment K levels in serum, they might be ''normal'', but when you Tx DKA, you add saline and Insulin, and insulin shifts K inside again, hypokalemia can be very dangerous, that's why the concept is constantly asked in usmle.
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Old 02-26-2012
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In DKA,due to acidic pH,the K+ shifts from intracellular to extracellular space.
also due to lack of insulin,more K+ is present in the ECF than normal.
But due to osmotic diuresis,glucose tags along not only water but also Na+ and K+ with it.
so in total what happens in DKA is
1.Decreased total(ICF + ECF) K+
2.Decreased ICF K+
3.Increased ECF K+

Therefore tests show false hyperkalemia (raised ECF k+) when in reality there is decreased overall K+ of body.
Administration of insulin causes rapid shift in K+ inside cells and then the true Hypokalemia can be seen in tests.
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