Renin–angiotensin–aldosterone system inhibitors lower hemoglobin and hematocrit only in renal transplant recipients with initially higher levels

• RAAS inhibitors are effective in lowering Hb and Htc in recipients with high or high/normal levels.
• The use of these drugs has a beneficial impact on erythropoiesis and kidney graft function.
• Clinicians should not be worried about their use in RTRs.
• The exact mechanism for these observations still has to be investigated.

AimWe have analyzed the effects of renin–angiotensin–aldosterone system (RAAS) inhibitors on evolution of hemoglobin (Hb) and hematocrit (Htc) levels as well as on the evaluation of kidney graft function in stable renal transplant recipients (RTRs) in respect with initially higher or lower Hb and Htc values.MethodsThe study group comprised of 270 RTRs with stable graft function. Besides other prescribed antihypertensive therapy, 169 of them have been taking RAAS inhibitors.ResultsWe wanted to analyze the effect of the use of RAAS inhibitors on Hb and Htc in patients with initially higher or lower Hb/Htc values. For this analysis, only RTRs that were taking RAAS inhibitors were stratified into two groups: one with higher Hb and Htc (initial Hb ≥ 150 g/L and Htc ≥ 45%) and another one with lower Hb and Htc (initial Hb < 150 g/L and Htc < 45%) values. Thirty-four RTRs with initially higher Hb and 41 RTRs with initially higher Htc had a statistically significant decrease in Hb (p = 0.006) and Htc (p < 0.0001) levels after 12-months of follow-up. In the group of patients with initially lower Hb (135 RTRs) and Htc (128 RTRs) there was a significant increase in Hb (p = 0.0001) and Htc (p = 0.004) levels through the observed period. The use of RAAS inhibitors has been associated with a trend of slowing renal insufficiency in RTRs (p = 0.03).ConclusionRAAS inhibitors lower Hb and Htc only in RTRs with initially higher levels. In patients with initially lower Hb and Htc levels, the use of these drugs is followed by beneficial impact on erythropoiesis and kidney graft function.