I enjoy your website RheumNow and your weekly highlights. Old guys like me need to be "spoon-fed". In regards to mistakes with methotrexate, I have 2 concerns: 1. Many people are being characterized as having CKD based on automated chemistry. Calculated GFR's and CrCls indicate stages 1-4. At what point should I be concerned about methotrexate toxicity? Should I get serum or red cell methotrexate levels or use any of the other testing for methotrexate toxicity available commercially such as 5,10-Methylenetetrahydrofolate reductase (MTHFR) ? Is there a "standard of care" in the setting of CKD? 2. Please note that the likelihood of methotrexate toxicity in greatly increased when a patient is admitted to a SNF or other long term care situation where weekly meds are unusual. The staff may change qweekly to qdaily because they think there is a typo error. David S. Knapp, MD (semi-retired)