The Renin Rise With Aliskiren: It’s Simply Stoichiometry

To the Editor: With great interest we read Campbell’s1 interpretation of plasma renin concentration in patients receiving aliskiren. The renin rise appears to be larger than the rise observed during angiotensin (Ang)-converting enzyme inhibition or Ang II receptor blockade.2 Indeed, it has been suggested that this may lead to a rise in Ang II.2 However, neither a rise in Ang II nor the putative subsequent rise in blood pressure have been observed thus far,3 possibly because the apparent renin rise is attributable, at least partly, to an assay-related artifact, allowing prorenin to be detected as renin.3,4 Irrespective of the cause of this rise and whether the rise is exaggerated, an aspect that merits consideration is the renin-aliskiren stoichiometry. Is the number …