Listening to Episode #14 of Core IM, I imagined discussing this case at VA morning report. For the past 20+ years, each month we have one session in which the chief residents present me acid-base &/or electrolyte cases to dissect. My discussion of this case is different from the podcast. That statement should not surprise anyone. This patient story lends itself to various discussions. I hope this blog post is complementary to the podcast.

1. The presentation of quadriparesis immediately made me consider severe hypokalemia. The patient had no trauma and did not have the classic GB story. Perhaps I lean to severe hypokalemia because I like discussing it.
2. Since the patient did in fact have severe hypokalemia I would stop and discuss a schema for severe hypokalemia. I divide my schema into 3 buckets – decreased bicarbonate normal gap acidosis, normal bicarbonate, and increased bicarbonate metabolic alkalosis. Let’s consider each bucket.
   1. Normal gap acidosis – either severe diarrhea (include increased ileal output in patients with ileostomies) or distal RTA. Distal RTA patients often have severe hypokalemia. The most common cause of distal RTA and severe hypokalemia is Sjogren’s syndrome. The additional clues noted in the podcast made this the leading possibility prior to the labs and virtually certain after hearing the labs.
   2. Normal bicarbonate – as discussed in the podcast either inherited periodic paralysis or hyperthyroid induced paralysis.
   3. Metabolic alkalosis – either mineralocorticoid excess or volume contraction (secondary to upper GI losses or diuretic use or both). For these patients a urine chloride – if low then it is a a volume contraction problem, if high mineralocorticoid. I have diagnosed an aldosterone adenoma that presented with acute quadriparesis. Recently they presented a patient who had excess licorice ingestion.
3. The labs strongly suggest the diagnosis – 136/1.9/119/<10/31/1.2 Since we are considering a distal RTA, I would have liked to have the U/A also, but they did not report the U/A.
4. The reason I wanted the U/A is that distal RTA patients do not acidify the urine. A high urine pH in the face of a normal gap acidosis makes the diagnosis of distal RTA. The reason for the acidosis stems from the lack of sufficient acid to buffer the ammonia to ammonium. That lack explains the positive urine anion gap.
5. So the case is straightforward, until it was not. The patient had a phosphate of 1.5. Further urine studies showed increased phosphate excretion and glycosuria with a normal serum glucose. Thus the patient likely also had Fanconi’s syndrome. I did a quick literature search and found several case reports of Fanconi’s syndrome secondary to Sjogren’s and this one in particular of the combination of distal RTA and Fanconi’s