New comprehensive reference values for kidney function indexes across adult and geriatric ages in Chinese popuplation.

Background And Aims: China has the largest number of chronic kidney disease (CKD) patients. Current CKD definition has been challenged recently. We aim to reassess kidney function in healthy Chinese population, to provide a more appropriate reference range (RIs) for diagnosis, treatment, monitoring (or screening) of kidney disease and related research.

Materials And Methods: A total of 49627 apparently healthy people aged 18-94 years old were enrolled. Age and sex effects were explored for the kidney function indicators and RIs were calculated non-parametrically.

Results: Albumin's limits were lower than the national RIs, with 5.7 g/L lower in upper limit (UL) and 0.4 g/L lower in lower limit (LL) [RIs: 39.6-49.3 vs 40-55]. The LL of estimate glomerular filtration rate (eGFR) was 80.4 mL/min/1.73 m or 63.3 mL/min/1.73 m at the age of <50 or ≥70 years, respectively. Notably, eGFR showed an approximately 0.7 mL/min/1.73 m decrease every year. In addition, eGFR increase 0.35 mL/min/1.73 m per standard deviation increase in blood glucose when uric acid (UA) exceed the RIs.

Conclusion: UA was an important factor affecting eGFR. For healthy elderly in China, albumin's limits were lower than the national RIs, and LLs of eGFR were nearly 60 mL/min/1.73 m. Using national RIs for healthy elderly may be overly stringent.