Hi JMF,
Houttuynia has been shown to reduce the oxidative stress and nephrotoxicity (kidney toxicity) induced by gentamicin, this may or may not extend to other antibiotics. Also it has been shown to reduce glycative and oxidative stress in the kidneys of diabetic rats. It's also anti-inflammatory.
So one of the questions to maybe figure out, is if it's indeed the high BP causing the kidney numbers to be borderline like that, or if it's something else causing it. For example, something else she's taking? Where the Houttuynia actually reduced that issue one summer.
Here are 4 relevant papers by the way:
https://link.springer.com/article/10.1007/s00394-015-0994-yhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmc3834437/https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0230645https://www.spandidos-publications.com/10.3892/etm.2015.2467