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BSA-Adjusted (De-indexed) eGFR

Convert eGFR from mL/min/1.73 m² to mL/min for the patient's actual body size.

For healthcare professionalsKidneyv1.0.1

For healthcare professionals / clinical use. Not a self-diagnosis tool.

Your measurements

mL/min/1.73 m²

Calculated on your device. Nothing is sent to a server.

Your result will appear here

Enter your measurements, then press Calculate.

Methodology

De-indexing by Mosteller BSA

GFR (mL/min) = eGFR × BSA ÷ 1.73

KDIGO 2024 says eGFR not indexed for body surface area may be indicated at extremes of body weight, especially for medicines with a narrow therapeutic range.

Who it is for
Adults, typically for drug dosing at extremes of body size.
Version
1.0.1

How this calculator works

Where the formula comes from

  • Mosteller (1987) published a simplified body-surface-area formula: the square root of height (cm) × weight (kg) ÷ 3600.[1]

The inputs

  • KDIGO 2024 reports eGFR relative to a body surface area of 1.73 m² in adults; non-indexed eGFR can be obtained by multiplying indexed eGFR by the person's BSA and dividing by 1.73.[2]

Where accuracy falls (published evidence)

  • KDIGO notes that drug clearance relates more strongly to non-indexed than to indexed eGFR, so using indexed eGFR in very small or large people can lead to over- or under-dosing.[2]

What guidelines say

  • KDIGO 2024 (Practice Point 4.2.4) says that in people with extremes of body weight, eGFR non-indexed for BSA may be indicated, especially for medicines with a narrow therapeutic range or that need a minimum concentration.[2]

Sources

  1. Mosteller RD. Simplified calculation of body-surface area. N Engl J Med. 1987;317(17):1098. doi:10.1056/NEJM198710223171717
  2. Kidney Disease: Improving Global Outcomes (KDIGO) CKD Work Group. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int. 2024;105(4S):S117–S314. doi:10.1016/j.kint.2023.10.018

Compiled from the published sources above. Every statement was agreed independently by three AI research tools (Claude, ChatGPT, DeepSeek) and its source verified in PubMed or Crossref by the Hakeemly editorial team. Not reviewed by a doctor unless stated. Agreed on

Worked example: how to calculate de-indexed eGFR

Inputs

eGFR
60 mL/min/1.73 m²
Height
180 cm
Weight
100 kg

Result

Absolute GFR
78 mL/min
Body surface area (Mosteller)
2.24 m²

Calculation:

√(18000/3600) = 2.236; 60 × 2.236/1.73 = 77.55

An illustration with sample values, worked out with the same method the tool above uses.

Limitations

  • Follow drug labelling, which may specify Cockcroft–Gault instead.

References

  1. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney Int. 2024;105(4S):S117–S314. doi:10.1016/j.kint.2023.10.018
  2. Mosteller RD. Simplified calculation of body-surface area. N Engl J Med. 1987;317(17):1098. doi:10.1056/NEJM198710223171717

Continue with your measurements

Shared measurements carry over automatically, in this tab only.

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