Renal & Fluids

Renal function drives dose adjustment for a large number of drugs, which makes creatinine clearance one of the most consequential numbers in pharmacy. This group covers Cockcroft–Gault — the equation most product labelling is written around, and not the same quantity as a laboratory-reported eGFR — alongside maintenance fluid requirements, infusion rate and drop factor conversions, and the BUN to creatinine ratio. Each states where the estimate stops being reliable: unstable renal function, extremes of body habitus, and low muscle mass.

4 calculators1 high-risk

Creatinine clearance (Cockcroft–Gault) High-risk

Estimate creatinine clearance from age, sex, serum creatinine, and weight — the equation on which most renal dose adjustments in product labelling are based.

Maintenance fluid requirements

Estimate daily maintenance fluid requirements by the Holliday–Segar method, the >20 kg shorthand, and the adult 30–40 mL/kg/day range.

Infusion rate & drop factor

Convert between infusion rate in mL/hr, drops per minute, and total infusion time.

BUN : creatinine ratio

Calculate the ratio of blood urea nitrogen to serum creatinine, a supportive indicator of volume status and the pattern of renal impairment.

High-consequence calculations in this group

These carry a greater risk of harm if the result is wrong or misapplied. Each states its own limits on its page; read them before acting on a number.

  • Creatinine clearance (Cockcroft–Gault) — Estimate creatinine clearance from age, sex, serum creatinine, and weight — the equation on which most renal dose adjustments in product labelling are based.

Guides for this category

Which Body Weight to Use for Drug DosingHow to Calculate Creatinine Clearance (Cockcroft–Gault)Creatinine Clearance vs eGFR

Where to go next

  • Guides — longer explanations of how to work through a calculation and how to choose between related calculators.
  • Practice problems — one worked problem for every calculator, solutions hidden until you open them.
  • Reference tables and formula sheet — every constant and conversion factor used here, with citations.
  • All 58 calculators — the full index, filterable by category.

Other categories

Measurement & ConversionsConcentrations & CompoundingDosing & Body MetricsNutrition SupportPharmacokineticsAcid-Base & LaboratoryPhysical PharmacyBiostatistics & OutcomesTherapeutic ConversionsDiabetes & LipidsPublic Health & Misc

Also known as

CrCl · creatinine clearance · cockcroft · gault · renal function · kidney function · renal dosing · GFR · maintenance fluid · holliday segar · 4-2-1 · fluid requirement · hydration · mL/kg/day · drip rate · drops per minute · gtt/min · flow rate · infusion · drop factor · IV rate · BUN SCr · BUN creatinine ratio · dehydration · prerenal · volume depletion · azotaemia