Your estimated GFR places your kidney function into one of the standard CKD (Chronic Kidney Disease) stages. Stage 1 (GFR 90 or above) represents normal kidney function. Stage 2 (GFR 60-89) indicates mildly decreased function, which is common in older adults and may not require medication adjustment for most drugs. Stage 3 (GFR 30-59) represents moderately decreased function and is the stage at which many renally cleared medications require dose reduction or interval extension. Stage 4 (GFR 15-29) indicates severely decreased function, where most renally cleared drugs need significant adjustment. Stage 5 (GFR below 15) represents kidney failure (ESRD), where dialysis-specific dosing guidelines apply.

The general approach to dose adjustment involves either reducing the dose while maintaining the standard interval, extending the interval while maintaining the standard dose, or a combination of both. The specific strategy depends on the drug's pharmacokinetic properties, therapeutic index, and whether efficacy depends on peak concentration or time above a threshold concentration.

Use this tool as a starting point whenever prescribing medications to a patient with known or suspected renal impairment. It is particularly important when initiating therapy with drugs that have significant renal clearance, when a patient's renal function has recently changed (acute kidney injury, post-surgery, dehydration), or when transitioning a patient between care settings where medication reconciliation is being performed.

This tool is also useful for routine medication reviews in patients with chronic kidney disease, especially at CKD stage 3 and beyond. Common drug classes that frequently require renal dose adjustment include antibiotics (vancomycin, aminoglycosides, fluoroquinolones, beta-lactams), anticoagulants (DOACs, enoxaparin), antidiabetic agents (metformin, sulfonylureas, SGLT2 inhibitors), cardiovascular drugs (digoxin, ACE inhibitors, sotalol), and analgesics (gabapentin, pregabalin, NSAIDs).

This tool provides general CKD staging and broad dose adjustment guidance only. It does not provide drug-specific dosing recommendations, which vary widely between individual medications even within the same drug class. Always consult the specific drug's prescribing information, a clinical pharmacology reference (such as Lexicomp, Micromedex, or the Renal Drug Handbook), or a clinical pharmacist for precise dosing in renal impairment.

The tool uses GFR (typically estimated by CKD-EPI), but many drug labels reference creatinine clearance estimated by the Cockcroft-Gault equation, which can give different values. This distinction matters most at the boundaries of dosing thresholds. Additionally, GFR-based staging does not capture acute changes in renal function, where drug accumulation can occur rapidly. In acute kidney injury, more frequent monitoring and conservative dosing are warranted even if the estimated GFR appears adequate. Patients on dialysis require specialized dosing that accounts for the dialyzability of each drug.