Endocrine Abstracts

Severe hyperkalemia post adrenalectomy is documented in the literature but not actively sought after in high risk post-operative patients.

Case: Fifty-one year old woman with a 12 year history of hypertension and hypokalemia. Her BP was controlled with amlodipine 10 mg OD. Serum aldosterone was 2832 pmol/l with undetectable renin activity leading to aldosterone to renin ratio (ARR) >28 000 pmol/l per ng/ml per h. Creatinine was 75 μmol/l with eGFR of 85 ml/min. CT showed a 3.5 cm low density left adrenal mass and adrenal vein sampling confirmed left lateralization. She underwent left adrenalectomy. At the time of discharge serum creatinine was 71 umol/l, with potassium of 3.8 and eGFR of 85 ml/min. Her serum aldosterone was <70 pmol/l and renin activity of 0.36 ng/ml per h yielding ARR <194. She was readmitted after 3 months with potassium of 6.7 and serum creatinine of 154. She was started on fludrocortisone and her creatinine dropped to 123 with improvement in potassium of 5.2. On discontinuing fludrocortisone after 4 months her serum creatinine rose again and reached a new baseline level of 180 mmol/l, eGFR 28 ml/min.

Discussion: While overt pre-existing renal impairment may be a strong factor in predicting post-operative hyperkalemia. Evidence suggests that PA itself may induce a hyper-filtration injury that may mask renal impairment until the operative reversal of the phenomenon.

Conclusion: Hyperkalemia screening should be actively considered in high risk patients. Older age (>53), longer duration of hypertension (>10 years), impaired pre-op (<58 ml/min) and post-op GFR and higher levels of pre-op aldosterone and are all known risk factors. The long term cure of primary hyperaldosteronism and hypertension is expected to yield renal benefits but development of irreversible post adrenalectomy renal impairment after a long duration of hypertension may argue for earlier consideration of a PA diagnosis in hypertensive populations.