STOPPING MEDS BEFORE TESTING FOR ALDOSTERONOMA 23 Feb 2015

STOPPING  MEDS  BEFORE  TESTING  FOR  ALDOSTERONOMA  23 Feb 2015

QUESTION-I have a 44 year old female who has primary hyperaldosteronism. She ceased spironolactone 6 weeks prior to AVS and amiloride one week ago. Despite increasing KCL tablets to 16 per day, she was admitted to hospital with hypokalaemia (K -2.4 mmol/L). my question is :

Is it imperative that amiloride be ceased prior to AVS? If so what is the minimum length of time that it needs to be stopped for?  Nirupa Sachithanandan,MBBS FRACP PhD  Diabetes, Endocrine, Pituitary and Familial Cancer Clinic

RESPONSE-Dear Dr. Sachithanandan, Your enquiry about your patient was  forwarded to me for comment.  The first  points is actually whether AVS in needed in this patient. She is young (43 years of age) and appears to have profound hypokalemia.  I am assuming also that the PA/PRA ratio was very abnormal since I would guess that the aldosterone level would be quite high and the PRA level undectable.  In such young patients if there is a clear cut lipid rich adenoma on one gland and the contralateral gland is anatomically normal  the diagnosis of an APA seems secure and I would directly refer such a patient to adrenalectomy without  AVS sampling.

In older patients or subjects with bilateral adrenal nodularity AVS is clearly needed.  Spironolactone may need to be stopped for up the 3 months, that is until the PRA has again become suppressed. Amiloride would also need to be stopped for weeks since its effect on PRA secretion is identical to that of spironolactone.  In such cases I check a PRA level prior to the AVS to be certain that the PRA level is not in the normal, detectable range( since it would impact on lateralization). A good strategy in such patients would be to stop both agents and check a PRA level monthly before proceeding to AVS.  The down side of stopping these agents is what you have encountered, that is, severe hypokalemia that is difficult to reverse with potassium supplementation. I hope this helps in the care of your patient. Dr RH Dluhy