Cannabis and the Kidneys: A Quick Guide for Patients and Doctors

Cannabis and the Kidneys: A Quick Guide for Patients and Doctors

One of the blessings of my work that I never expected was the variety of cases I would see. Patients present to the office with a myriad of health complaints, many of which require that I hit the journals and books to step up my skills. I have one such patient who suffered from lupus nephropathy resulting in a nephrectomy. Their personal beliefs led them to me to help find treatment options that would decrease their use of pharmaceuticals for symptoms like pain, anxiety and insomnia. This led to me doing research on the matter which I feel I should share with you.  

Let’s Get Down to the Science of It….

Cannabis, also known as marijuana (Weed, Mary Jane, Ganja, etc.) is becoming increasingly prevalent across the United States. Although still federally illegal, a vast majority of the US states have some sort of legal marijuana program (medical marijuan and/or adult use). In 2018 alone, over 22 million Americans reported using cannabis, according to the National Survey on Drug Use and Health. This upward trend is particularly notable among older adults aged 50 and over, an age group enriched with patients suffering from chronic kidney disease (CKD).

A recent comprehensive review published in Current Opinion in Nephrology and Hypertension took a deep dive into examining the relevance of cannabis and its constituent compounds like THC and CBD to the practice of nephrology. Led by Dr. Joshua Rein, the article provides an overview that all kidney health professionals should be aware of.

One area where cannabis may offer potential benefits is in treating the chronic symptoms experienced by many CKD and end-stage renal disease (ESRD) patients. Up to half of this patient population struggles with issues like pain, nausea, loss of appetite, insomnia, depression and anxiety]. Several of these are approved indications for medical cannabis in states with legalized programs. Moreover, in the midst of the ongoing opioid crisis, cannabis could represent an alternative for pain management that reduces the need for opioid prescriptions.

That’s the good news. The bad news is that the impact of cannabis itself on kidney function remains unclear, with studies offering conflicting results. A retrospective analysis found self-reported cannabis use was associated with a more rapid decline in estimated glomerular filtration rate (eGFR) among CKD patients . In contrast, data from the large Chronic Renal Insufficiency Cohort (CRIC) Study did not find any link between cannabis use and CKD progression over 5 years of follow-up. 

For healthy people without kidney disease, long-term studies like CARDIA and NHANES have not demonstrated any clinically significant effects of cannabis consumption on measures of kidney function such as eGFR and albumin levels. However, the authors still caution that renal function should be closely monitored in CKD patients using cannabis, that the lowest effective doses should be used, and that smoking cannabis should be avoided due to associated respiratory risks. As someone who does not tolerate smoking very well, I always encourage my patients to try other routes of administration like tinctures, capsules and edibles. These options may provide longer therapeutic effects and less potential for airway irritation.

Cannabis use may also have implications for kidney transplantation. At some centers, cannabis abuse or dependence could contribute to a patient being denied listing or delayed for transplant due to concerns over medication adherence and outcomes. However, a national study did not find any association between pre-transplant cannabis abuse/dependence and higher risks of graft failure or death in the first year post-kidney transplant. There are also case reports suggesting CBD, the non-psychoactive cannabinoid, may increase calcineurin inhibitor levels like tacrolimus - a potential drug interaction to watch for.

From a safety standpoint, synthetic cannabinoid products like "K2" or "Spice" have been linked to cases of acute kidney injury and should be avoided.  The authors also warn about the proliferation of unregulated CBD products that may contain inaccurate labeling, contaminants like THC, and make unsubstantiated health claims. Third-party testing is highly advisable for any CBD products before use. My recommendation is to never buy any products for chronic medical conditions from places like smoke shops or gas stations. You should try to only purchase from reputable, trusted brands. 

Ultimately, while cannabis and cannabinoids may offer some potential therapeutic benefits for CKD and ESRD patients, there remains a lack of high-quality data and clinical guidance for nephrologists stemming from the federal restrictions that have historically impeded cannabis research. As more states move towards cannabis legalization, researchers and physicians emphasize that further studies will be critical to elucidate the impacts, pharmacology, safety parameters, and best practices for the medical use of marijuana. Critical to this would be the federal rescheduling of cannabis from a category I controlled substance.

You can review the main article here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7012334/

Sources:

1. https://www.samhsa.gov/data/sites/default/files/cbhsq-reports/NSDUHNationalFindingsReport2018/NSDUHNationalFindingsReport2018.pdf
2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6024284/
3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7012334/
4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1781412/
5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6676584/
6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6145078/
7. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6135562/
8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5332315/
9. https://jasn.asnjournals.org/content/29/2/479
10. https://cjasn.asnjournals.org/content/13/7/993
11. https://cjasn.asnjournals.org/content/12/9/1578
12. https://www.amjmed.com/article/S0002-9343(17)31236-1/fulltext
13. https://onlinelibrary.wiley.com/doi/full/10.1111/petr.13467
14. https://onlinelibrary.wiley.com/doi/full/10.1111/ctr.13456
15. https://journals.lww.com/transplantjournal/Fulltext/2019/11000/Cannabis_Dependence_or_Abuse_in_Kidney.5.aspx
16. https://onlinelibrary.wiley.com/doi/abs/10.1111/ajt.15519
17. https://www.sciencedirect.com/science/article/abs/pii/S0041134519300512
18. https://www.cdc.gov/mmwr/preview/mmwrhtml/mm6206a1.htm
19. https://jasn.asnjournals.org/content/24/2/198
20. https://jamanetwork.com/journals/jama/article-abstract/2661569
21. https://www.mayoclinicproceedings.org/article/S0025-6196(19)30490-3/fulltext