*Purpose: The prevalence of primary aldosteronism (PA) in the general hypertensive (HTN) population is more than 5%, and substantially higher at 20% in certain high-risk groups, e.g. patients with resistant HTN. PA is associated with worse cardiovascular and renal outcomes compared to matched individuals without PA but with similar degree of BP elevation. The 2016 Endocrine Society Guidelines explicitly recognize PA as a major public health issue requiring urgent attention. However, the prevalence of PA in kidney transplant recipients (KTRs) is unknown.

*Methods: We screened KTRs with a functioning graft who had HTN and were 1) on ≥ 4 anti-HTN meds, 2) on 3 anti-HTN meds with BP ≥ 140/90, 3) on potassium supplements, or 4) were hypokalemic. Patients who had already been screened for PA or were on mineralocorticoid antagonists (MRA) were excluded. Anti-HTN meds were not altered prior to plasma aldosterone concentration (PAC) and plasma renin activity (PRA) testing.

*Results: 280 patients met our criteria. The most common inclusion criterion was the use of ≥ 4 anti-HTN meds. 88% were on beta-blockers, 74% on calcium channel blockers and 63% on ACEI/ ARBs. 172 (61.4%) successfully completed the PAC and PRA testing. A positive screen for PA defined by aldosterone-to-renin ratio (ARR) of ≥ 20 and PAC > 15 ng/dL yielded a prevalence of 15.7% (27/172). There were no statistically significant differences in baseline characteristics between the group that screened positively for PA (PA) versus negative (PA-), including age, gender, race distributions, time since transplant, use of CNI sparing regimens and frequency of repeat transplantations. The PA+ patients were more likely to have met screening criteria based on potassium supplement requirement (52% vs. 27%, p = 0.01) and hypokalemia (25.9% vs. 4.8%, p<0.01) than PA- patients. 67% of the PA+ patients were on potassium supplements and/or were hypokalemic. Subsequent management of the PA+ patients was determined by the individual transplant nephrology provider. None of the patients underwent confirmatory testing with oral sodium loading or saline infusion testing. 56% (15/27) of PA+ patients were successfully started on MRA.

*Conclusions: While there are several case reports documenting “unmasking” of PA after kidney transplantation, our study is the first to systematically explore the prevalence of PA in the KTR population, which has inherently high cardiovascular risk. When hypokalemia is noted in hypertensive kidney transplant recipients, strong consideration should be given to screening for PA. Exclusion of patients who had previously been screened or were already on MRA, and continuation of ACEI/ARBs through testing likely led to under-estimation of prevalence. Further studies are needed to determine the cardiovascular and renal risk attributable to PA, and define optimal therapy for KTRs with PA.

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