HyperKalemia Challenge

35yo Indian male with no PMHx presents to PMD for routine physical and labs. He is found to have a K of 6.8meq/l and sent to hospital for admission and w/u. These results are repeated and verified. The patient has no symptoms or any significant PMHx. He denies use of NSAIDs or any other OTC meds or herbs with the exception a pinch of tamaric powder once or twice daily for a couple of weeks due to inadvertent biting of his tongue. He denies high risk behaviour (HIV risk factors).

Exam is unremarkable as are vitals. Serial labs show HCO3 ranging from 20 - 27 (mostly in low to mid 20s). UA is unremarkable with pH running 5.5. Initial UNa 200meq/l and Uk 30 initially, repeated (for TTKG) shows Una 117 and Uk 12 with TTKG <2. His Cr runs from 0.9 to 1.2. His PRA is 0.12 and Aldo <1 at the time of presentation. Serum cortisol is normal. His medicine team orders MRI abd for some reason and adrenals are remarked as "small".

The nephrologist on the case believes he has Type IV RTA, but etiology is unclear to him. He is treated medically and his K ultimately improves and he is discharged home on fludrocortisone.

He is then seen in the office. It was decided to attempt to see if his renin/aldo levels are inducible through volume depletion and also look for aldo synthase deficiency. His fludrocortisone is stopped for 5 days and he is started on Lasix 20mg BID and subsequent labs only on the lasix for 5 days:

Deoxycorticosterone slightly high and 18-Hydroxycorticosterone high, but 11-deoxycortisol, corticosterone, cortisol all WNL and PRA 1.4 and aldo 27! His BP is not typically more than 130s systolic, however the consideration of Gordon's Syndrome (pseudohypoaldo type 2) is given, and the decision try HCTZ and look for response of K and TTKG.

Differential?