08/09/2026
Two people, both eGFR 42. One is stable and will be for years. The other is in trouble.
Same number. Here is what separates them.
**Protein in the urine.** The single biggest difference. eGFR tells you how much filtering is happening. uACR tells you whether the filter is leaking. Two people at 42, one leaking protein and one not, are not in the same situation at all.
**The direction of travel.** 42 on the way down from 60 is a different story from 42 on the way up from 33. One number is a dot. Two numbers are a line, and only the line means anything.
**What caused it.** Diabetic kidney disease, high blood pressure, an autoimmune cause and a structural cause all behave differently over time.
**Age and muscle.** eGFR is estimated from creatinine, and creatinine comes partly from muscle. A muscular 40-year-old and a frail 80-year-old with identical readings are not equivalent.
So when someone tells you their number, and it sounds worse or better than yours, you are comparing one letter from a much longer sentence.
Yours is the only one that matters, and the trend in yours matters more than today's figure.