Homocysteine processing depends primarily on vitamins B6, B12, and folate (5-MTHF). Persistent elevations may be associated with vitamin insufficiency, excess methionine intake, inborn errors of metabolism, and renal impairment.
Although we don’t provide individual clinical assessment or guidance at ODX, we would like to address your questions as best we can.
You are correct, renal impairment can contribute to elevations in serum homocysteine due to decreased excretion. Though this is discussed in the FBCA Mastery course and some of the research blog posts, it was missing from one post that focused on cardiovascular disease. We have updated that post to include this important factor. It is also referred to in the upcoming Biomarker Handbook Update.
Although you mentioned renal function in your question it wasn’t clear if your client had optimal kidney function or not (?).
It may be prudent to assess her vitamin B6 status as well. Vitamin B6 regulates an alternate pathway for processing homocysteine which involves irreversible transsulfuration to cysteine which can then be used for protein or glutathione synthesis (Polyzos 2012). The biologically active form of B6, pyridoxal 5’-phosphate, is a cofactor for cystathionine-synthase (CBS) and cystathionine-lyase, enzymes in this alternate pathway (Mascolo 2020).
Further investigations into inborn errors of metabolism, i.e., cystathionine beta-synthase deficiency, although a retrospective study used a cutoff above 30 umol/L as their starting point. Researchers note that one individual responded to B6 supplementation and decreased homocysteine even further with the addition of betaine supplementation (Gonzalez 2022).
Bioactive B6 should be found in a well-balanced multivitamin-mineral formula though dosing levels may vary.
The contribution of SIBO and the presence of depression should be further investigated.
You may want to review some blog posts we have written on Homocysteine:
References
Brown, Mary J., et al. “Vitamin B6 Deficiency.” StatPearls, StatPearls Publishing, 18 July 2022.
Gonzalez, Aixa et al. “Elevated homocysteine levels: What inborn errors of metabolism might we be missing?.” American journal of medical genetics. Part A, 10.1002/ajmg.a.63001. 22 Oct. 2022, doi:10.1002/ajmg.a.63001
Mascolo, Elisa, and Fiammetta Vernì. “Vitamin B6 and Diabetes: Relationship and Molecular Mechanisms.” International journal of molecular sciences vol. 21,10 3669. 23 May. 2020, doi:10.3390/ijms21103669
Polyzos, Stergios A et al. “Serum homocysteine levels in patients with nonalcoholic fatty liver disease.” Annals of hepatology vol. 11,1 (2012): 68-76.