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Printed on 6/29/2026
For informational purposes only. This is not medical advice.
This tool classifies renal function by GFR into standard CKD stages and provides general guidance on medication dose adjustment. It is a starting point — always consult drug-specific dosing recommendations for individual medications. Calculate precise GFR with [eGFR Calculator](/tools/egfr-calculator) (estimated) or [Creatinine Clearance Calculator](/tools/creatinine-clearance) (estimated from Cockcroft-Gault). For vancomycin specifically, use [Vancomycin AUC/MIC Calculator](/tools/vancomycin-dosing). Monitor AKI with [BUN/Creatinine Ratio](/tools/bun-creatinine-ratio) and [FENa Calculator](/tools/fena-calculator).
Formula: GFR staging: Normal ≥90, Mild 60–89, Moderate 30–59, Severe 15–29, ESRD <15 mL/min/1.73m².
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Enter age, sex, weight, and serum creatinine. The Cockcroft-Gault formula calculates CrCl: males = [(140 − age) × weight in kg] ÷ [72 × SCr]; females = multiply by 0.85. Use actual body weight for most patients; for obese patients use ideal body weight. CrCl in mL/min (not mL/min/1.73m²) is what most drug package inserts reference.
CrCl guides drug dose adjustments across CKD stages. Most drugs requiring renal adjustment have dosing thresholds at CrCl <50, <30, or <15 mL/min. Common examples: metformin dose reduction at CrCl 30–45 and contraindicated <30; most DOACs have renal dose adjustments; aminoglycosides require interval extension below CrCl 60; NSAIDs should be avoided if CrCl <30.
Use CrCl as the denominator to compare against the drug's package insert thresholds. In hospitalized patients with AKI, reassess CrCl daily — serum creatinine can change rapidly, requiring immediate dose adjustment. For patients on dialysis, consult drug-specific dialyzability tables as hemodialysis can significantly alter drug clearance.
Hospitalists & Infectious Disease
Beta-lactams (piperacillin-tazobactam, meropenem), fluoroquinolones (levofloxacin, ciprofloxacin), and renally cleared antibiotics all require dose reduction or interval extension in renal impairment. In AKI, daily reassessment is essential — underdosing risks treatment failure; overdosing risks toxicity including seizures (carbapenem at excessive doses).
Endocrinologists & Primary Care
Metformin requires dose reduction to 1000 mg/day at CrCl 30–45 mL/min and should be stopped at CrCl <30 due to lactic acidosis risk. SGLT2 inhibitors have efficacy thresholds (empagliflozin efficacy reduced below CrCl 30; dapagliflozin for HF can be used to eGFR ≥25). Sulfonylureas accumulate in CKD, causing hypoglycemia.
Cardiologists & Hematologists
Direct oral anticoagulants require CrCl-based dosing: apixaban dose reduction uses ARISTOTLE criteria (SCr ≥1.5 mg/dL + age ≥80 or weight ≤60 kg, any 2 of 3 criteria); rivaroxaban should be avoided if CrCl <15 and reduced to 15 mg daily for AF if CrCl 15–49; dabigatran is contraindicated at CrCl <15 and requires reduction at CrCl <30.
Hospitalists & Clinical Pharmacists
Hospitalized patients frequently develop AKI from sepsis, contrast, or dehydration. Reviewing all renally-cleared medications daily using the current CrCl prevents accumulation toxicity. This includes H2-blockers, gabapentin/pregabalin, direct antivirals, and NSAIDs that are commonly overlooked.
Oncologists & Oncology Pharmacists
Many chemotherapy agents (carboplatin, methotrexate, bleomycin, pemetrexed) require precise CrCl-based dose calculation to avoid life-threatening toxicity. Carboplatin AUC dosing uses the Calvert formula with GFR as a direct input. Nephrology consultation before nephrotoxic chemotherapy in CKD patients is standard of care.
Drug package inserts were studied using Cockcroft-Gault CrCl, not CKD-EPI eGFR. These equations give different values, especially in elderly, obese, and black patients. When a drug label says 'reduce dose at CrCl <50 mL/min,' use Cockcroft-Gault CrCl — not eGFR — for that threshold comparison.
CKD-EPI eGFR (mL/min/1.73m²) is the standard for staging CKD (G1–G5) and estimating kidney disease progression. Cockcroft-Gault CrCl (mL/min) is used for drug dosing in most FDA-approved drug labels. A patient might have an eGFR of 58 but a CrCl of 45 — or vice versa — depending on body size and age.
The 2016 FDA label update for metformin allows continued use at CrCl 30–45 mL/min with dose reduction (max 1000 mg/day) and more frequent monitoring. Metformin should be stopped if CrCl falls below 30 mL/min (or eGFR <30) due to lactic acidosis risk. Always recheck before contrast procedures.
The ARISTOTLE criteria for apixaban dose reduction: if the patient meets 2 of 3 criteria (SCr ≥1.5 mg/dL, age ≥80, weight ≤60 kg), reduce to apixaban 2.5 mg twice daily. This is NOT purely based on CrCl threshold — many clinicians incorrectly use renal function alone for this calculation.
NSAIDs inhibit prostaglandin-mediated afferent arteriolar dilation, reducing GFR — especially dangerous in patients already dependent on prostaglandins for renal perfusion (CKD, heart failure, volume depletion). Avoid NSAIDs if CrCl <30 mL/min and use with extreme caution at 30–60 mL/min. Consider acetaminophen as a safer alternative.
Serum creatinine in AKI can rise 0.5–2 mg/dL per day during a severe insult. A dose that was appropriate on admission may be toxic by day 2 or 3. Review all renally-cleared medications daily in hospitalized patients with rising creatinine. Set a daily reminder to recalculate CrCl when SCr changes.
Hemodialysis and peritoneal dialysis patients require drug dosing that accounts for dialyzability (how much drug is removed by each session), interdialytic drug clearance, and the type of dialysis modality. Many drugs must be dosed after hemodialysis to prevent drug removal during the session. Consult a nephrology pharmacist for complex dialysis patients.
Metformin should be held 24–48 hours before and after iodinated contrast administration in patients with CrCl <60 mL/min, as contrast nephropathy could acutely worsen renal function and precipitate metformin-associated lactic acidosis. Restart only after renal function is confirmed stable.
Cockcroft-Gault equation published by Cockcroft & Gault (Nephron 1976) using SCr and body weight. FDA Drug Approval Guidelines use Cockcroft-Gault for pharmacokinetic studies in renal impairment. KDIGO 2012 recommends CKD-EPI for GFR staging but acknowledges CG is appropriate for drug dosing when that was the study basis. Metformin renal contraindication thresholds from FDA label update 2016 and NICE NG28. DOAC renal dosing from respective prescribing information and validated dosing algorithms.
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.
Disclaimer: This tool is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your health.
April 21, 2026 · trust-baseline
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