How is eGFR calculated?
eGFR is a formula, not a direct measurement. Your lab measures creatinine, a waste product of muscle and protein, and plugs it into an equation with your age and sex to estimate how much blood your kidneys filter each minute.
The equation changed in 2021. The National Kidney Foundation and the American Society of Nephrology formed a task force that recommended dropping race from kidney function estimates, and the NKF’s eGFR calculator now uses the race-free CKD-EPI creatinine equation (2021). If an older report showed two eGFR values labeled by race, that format is outdated. Your current result should show a single number.
For context, the MedlinePlus encyclopedia gives a typical creatinine range of 0.7 to 1.3 mg/dL for men, noting that ranges vary among labs and with muscle mass.
What do the stage numbers mean?
The National Kidney Foundation groups eGFR into stages. Stages 1 and 2 count as kidney disease only when there is other evidence of damage, such as protein in the urine.
| Stage | eGFR | What it means |
|---|---|---|
| 1 | 90 or above | Normal filtering; disease only if damage shows up elsewhere |
| 2 | 60 to 89 | Mild loss; disease only with signs of damage |
| 3a | 45 to 59 | Mild to moderate loss |
| 3b | 30 to 44 | Moderate to severe loss |
| 4 | 15 to 29 | Severe loss |
| 5 | Under 15 | Kidney failure |
Age matters when reading these. The NKF lists average eGFR by decade: 116 in your 20s, 107 in your 30s, 99 in your 40s, 93 in your 50s, 85 in your 60s and 75 at 70 and older. A 62-year-old at 82 is close to average for his age, not automatically sick.
How do supplements, protein and training change the number?
Anything that raises creatinine without hurting the kidneys will push eGFR down on paper. The NKF’s creatinine page lists creatine supplements, a very muscular build, recent high-intensity exercise and large amounts of cooked meat among those factors.
For active men, this is the first thing to rule out when eGFR looks low. If you lift, take creatine or eat a high-protein diet and your eGFR lands lower than expected, the sensible next step is a better test, not alarm. Our page on the cystatin C test explains the kidney marker that muscle does not distort, and our creatine kinase test page covers the muscle side of hard training.
Do regular anti-inflammatories hurt your kidneys?
They can, and this is a real effect rather than a lab quirk. The NKF explains that NSAIDs lower blood flow through the kidneys, which can cause or worsen kidney disease, especially at higher doses and with long-term use. The group includes ibuprofen (Advil, Motrin), naproxen (Aleve), high-dose aspirin and stronger versions such as celecoxib and meloxicam.
For men who take ibuprofen most days for sore joints or training aches, that matters. The NKF advises people with kidney disease to avoid NSAIDs, especially with an eGFR under 60, and notes that topical diclofenac gel puts far less drug into the blood. If you rely on an anti-inflammatory regularly, tell the provider reading your labs. If you are also on testosterone, our page on TRT medication interactions covers other combinations worth flagging.
When does a low eGFR need a recheck?
Almost always before a label is applied. Kidney disease is defined by changes that last, so a single low number, especially after dehydration, a hard week of training or a big protein day, is repeated. The NKF suggests repeating the test in 3 months when eGFR is below 90 and adding a urine albumin test for a complete picture.
Some findings deserve a prompt visit rather than a routine recheck: a large drop from your previous result, an eGFR under 60 with no obvious explanation, or new swelling in your legs or feet, itching, nausea or a sharp change in how often you urinate. Our comprehensive metabolic panel page shows how eGFR sits alongside the other chemistry values.
How Ultimate Male reads your kidney numbers
Kidney function is part of the Targeted Preventative Health Panel and the Comprehensive Health Optimization Panel, drawn on site in San Gabriel and Downey with results usually back in 24 to 48 hours. Before the draw, mention creatine, protein shakes, recent heavy training and any regular pain relievers, since all of them shape how the number is read.
At your consultation, a PA-C or MD looks at eGFR against your age, build and habits, then decides whether you need a simple repeat, a cystatin C check, a urine test or a referral. Our liver and kidney function panel page explains that panel, and every option is listed on our preventative blood testing page.
