75 yo man with HTN, DM2, and BPH referred to renal clinic for evaluation of hypokalemia in 6/2014.
He was diagnosed HTN in 2001 with K+ 3.3. He had been on HCTZ and KCl from 2002 to 2007. In 5/2007, HCTZ was discontinued due to persistent hypokalemia despite KCl supplement and Lisinopril was started.
In 2012, his K was 3.4 on KCl 40 mEq daily and Lisinopril 40mg daily. Urine electrolytes showed UNa 98 and UK 70, serum Aldosterone was 13 ng/dl and plasma Renin less than 0.6 ng/mL/h.
TSH negative over this span with cortisol level of 9.6. In 6/2014 on his first visit, his BP was 164/85 on 3 medications (Lisinopril, metoprolol, amlodipine).
He feels well. No chest pain or SOB. No childhood HTN or hypokalemia to his knowledge. Currently eating a K rich diet. Notes low extremity swelling only when he started amlodipine. No cramping. Amiloride was added in 6/2014.
Follow-up visit in 11/2014 showed BP 122/74 with K 4.3. What's the differential for his low K?