Great case of hypokalemia presented by chief fellow @Laurenaring yesterday.
60 y/o woman with a h/o nasopharyngeal cancer, nephrology consulted for hypokalemia.
Sk 2.5, bicarb 30, normal kidney function. No diuretic use, denies vomiting or diarrhea. #nephtwitter #medtwitter
60 y/o woman with a h/o nasopharyngeal cancer, nephrology consulted for hypokalemia.
Sk 2.5, bicarb 30, normal kidney function. No diuretic use, denies vomiting or diarrhea. #nephtwitter #medtwitter
She was on pembrolizumab, which is a/w tubulointerstitial disease and subsequent hypokalemia d/t an RTA, however this was just started 5 days ago and her urine was bland.
Next step? As Nephrologists we want to know urine composition. In this case I would want a Uk, UCr and UCl
Next step? As Nephrologists we want to know urine composition. In this case I would want a Uk, UCr and UCl
Spot values are sufficient and hers were Uk 43, UCr 18 and UCl 50
If you live in the US then you have to deal with unit conversions: discussed here pbfluids.com/tag/potassium/
Her Uk/Ucr ratio was 27 (>2.5 is c/w renal K wasting)
If you live in the US then you have to deal with unit conversions: discussed here pbfluids.com/tag/potassium/
Her Uk/Ucr ratio was 27 (>2.5 is c/w renal K wasting)
Next step? I look at acid/base balance - she has a metabolic alkalosis - enter the UCl to help differentiate
💡that with bicarbonaturia you pull sodium along raising UNa levels, which is why UCl is the better test here
Her UCl is high
Next step?
💡that with bicarbonaturia you pull sodium along raising UNa levels, which is why UCl is the better test here
Her UCl is high
Next step?
Use BP to see if we can differentiate between something like Bartter's/Gitelman's syndromes or diuretic use vs conditions associated with increased ENaC activity
Her BP was high
Next step? serum aldosterone and renin levels
Her BP was high
Next step? serum aldosterone and renin levels
Both aldo and renin were undetectably low.
DDx here is Liddle's syndrome or conditions where cortisol is acting like aldosterone, i.e Cushing's disease, ACTH producing tumors, AME, glycyrrhizinic acid
Imaging not c/w cancer involvement of her pituitary or adrenals
DDx here is Liddle's syndrome or conditions where cortisol is acting like aldosterone, i.e Cushing's disease, ACTH producing tumors, AME, glycyrrhizinic acid
Imaging not c/w cancer involvement of her pituitary or adrenals
A 24h urine collection for cortisol and cortisone ultimately came back with a ratio of 2 (normal is 0.3-0.5)
This suggests either a deficiency in or inhibitor of the enzyme 11-beta-hydroxysteroid dehydrogenase which converts cortisol to cortisone
This suggests either a deficiency in or inhibitor of the enzyme 11-beta-hydroxysteroid dehydrogenase which converts cortisol to cortisone
On further questioning her family informed the team that she had been using a Chinese herb that contains black licorice root - which contains glycyrrhetic acid - a potent inhibitor of 11-beta-HSDH
She was started on amiloride which helped maintain normal potassium levels until the licorice wore off - ~10 days
Illustrates how important it is to ask about all supplements, herbs, etc.
Read about licorice induced hypermineralocorticoidism here: pubmed.ncbi.nlm.nih.gov/1922210/
Illustrates how important it is to ask about all supplements, herbs, etc.
Read about licorice induced hypermineralocorticoidism here: pubmed.ncbi.nlm.nih.gov/1922210/
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