See the DrugPatentWatch profile for methotrexate

Yes, there are specific kidney function tests that should be monitored when adjusting methotrexate dosage in elderly patients. Methotrexate is primarily excreted by the kidneys, and its clearance is reduced in elderly patients due to decreased renal function [1]. Therefore, it is crucial to monitor kidney function regularly in elderly patients receiving methotrexate therapy.

The recommended kidney function tests to monitor when adjusting methotrexate dosage in elderly patients include serum creatinine and estimated glomerular filtration rate (eGFR) [2]. Serum creatinine is a waste product that is excreted by the kidneys and can be used as an indicator of kidney function. An eGFR calculator can be used to estimate the glomerular filtration rate, which is the best overall index of kidney function [3].

It is essential to note that methotrexate has a narrow therapeutic index, and even slight changes in renal function can significantly affect its toxicity [4]. Therefore, healthcare providers should consider reducing the methotrexate dosage in elderly patients with impaired renal function to minimize the risk of toxicity [5].

In summary, monitoring serum creatinine and eGFR is crucial when adjusting methotrexate dosage in elderly patients to minimize the risk of toxicity. Healthcare providers should consider reducing the methotrexate dosage in elderly patients with impaired renal function.

Sources:

1. Methotrexate. Lexi-Drugs. [Online] Available: https://online.lexi.com/lco/action/doc/retrieve/docid/patch_f/751422 [Accessed: 2023-03-22]
2. Methotrexate. UpToDate. [Online] Available: https://www.uptodate.com/contents/methotrexate-drug-information?search=methotrexate&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1 [Accessed: 2023-03-22]
3. Estimated Glomerular Filtration Rate (eGFR). National Kidney Foundation. [Online] Available: https://www.kidney.org/atoz/content/estimated-glomerular-filtration-rate-egfr [Accessed: 2023-03-22]
4. Methotrexate. DrugPatentWatch. [Online] Available: https://www.drugpatentwatch.com/drugs/methotrexate [Accessed: 2023-03-22]
5. Methotrexate. American College of Rheumatology. [Online] Available: https://www.rheumatology.org/I-Am-A/Patient-Caregiver/Treatments/Methotrexate [Accessed: 2023-03-22]