image.jpg
Answer for this
Reading File
Finding Sources
Reading File
Answer: A. Potassium is lost through vomiting and osmotic diuresis
This question is about the management of Diabetic Ketoacidosis (DKA).
Why potassium replacement is needed despite high admission serum K+:
In DKA, the serum potassium on admission is often normal or even elevated, but this is misleading - it does NOT reflect true total body stores. Here's what's really happening:
1. Total body potassium is actually depleted due to:
- Vomiting - direct loss of potassium in gastric contents
- Osmotic diuresis - the profound glucosuria drives massive urinary losses of water AND electrolytes, including potassium (losses can be up to 7 mmol/kg)
2. Why does serum K+ appear high despite whole-body depletion?
- In metabolic acidosis, H⁺ ions shift into cells in exchange for K⁺ shifting OUT of cells into the bloodstream - this artificially raises serum K+ without reflecting true stores
- Insulin deficiency also impairs cellular K+ uptake, keeping it elevated in serum
3. What happens during treatment?
- Once insulin is given, glucose enters cells and K⁺ is driven back INTO cells (insulin activates Na⁺/K⁺-ATPase)
- As acidosis is corrected, the transcellular K⁺ shift reverses
- The serum potassium falls rapidly and sharply, sometimes to dangerously low levels
- Potassium replacement is therefore almost always required during treatment
Why the other options are wrong:
| Option | Why it's wrong |
|---|---|
| B. Insulin increases potassium levels | The opposite is true - insulin LOWERS serum K⁺ by driving it into cells |
| C. Acidosis causes renal potassium retention | Acidosis actually promotes K⁺ efflux from cells into serum (it does NOT cause renal retention) |
| D. Hyperglycemia increases total body potassium | Hyperglycemia and osmotic diuresis actually DEPLETE total body potassium |
| E. Potassium replacement is unnecessary | Clearly wrong - K⁺ replacement is a cornerstone of DKA management |
As confirmed by Goldman-Cecil Medicine: "Even when the serum potassium is elevated on the initial presentation of diabetic ketoacidosis owing to the metabolic acidosis, it quickly declines after insulin treatment is begun." Fluid losses of 5-10 L and potassium losses up to 7 mmol/kg are common in DKA.
This is a shared conversation. Sign in to Orris to start your own chat.