Estimated Glomerular Filtration Rate

Also written eGFR

Organ functionMeasured in mL/min/1.73m²Calculated, not measured

What it measures

An estimate of kidney filtration derived from serum creatinine together with age and sex, using a standard equation.

Why it matters

It is the primary tool for detecting and staging chronic kidney disease, which is common and largely asymptomatic until advanced.

Where the claimed ranges actually sit

Measured in mL/min/1.73m². Each row is one claim about where your result should fall.

What a laboratory reportsWhat a seller markets as “optimal”

Laboratory reference range> 60 mL/min/1.73m²

Established chronic kidney disease staging criteria

Above 90 marketed as optimal kidney functionD> 90 mL/min/1.73m²

Longevity platforms and biological age products

›View as table

Claim	Range	Source
Laboratory reference range	> 60 mL/min/1.73m²	Established chronic kidney disease staging criteria
Above 90 marketed as optimal kidney function	> 90 mL/min/1.73m²	Longevity platforms and biological age products

Where the sources disagree

The clinical thresholds are well established and not seriously contested. The problem is that eGFR is derived rather than measured, and its input is confounded by muscle mass in precisely the audience buying longevity panels. Anyone with substantial muscle or on creatine should ask for cystatin C, which does not depend on muscle mass, before accepting a low eGFR at face value.

The marketed ranges, examined

Each claim gets its strongest possible case before it gets its criticism. Several of these are substantially correct.

Above 90 marketed as optimal kidney function

Promoted by longevity platforms and biological age products

DUnsupported

The strongest case for it

eGFR declines with age, and a higher value in midlife does indicate more preserved filtration reserve.

What it leaves out

eGFR is calculated from creatinine, which is produced by muscle. A muscular person or anyone supplementing creatine will show a lower eGFR without any kidney impairment whatsoever. Marketing a high target to a fitness-oriented audience reliably generates false alarms in exactly the people least likely to have kidney disease.

Before you act on your result

Calculated, not measured; confounded by muscle mass and creatine supplementation.
Cystatin C-based estimates are more reliable in very muscular or very frail people.
The current standard equation no longer includes a race coefficient.

Last reviewed July 28, 2026How we grade evidence and attribute claims →

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