Unfortunate Terminology

Letters to the Editor regarding the article The Early Diagnosis and Treatment of Chronic Renal Insufficiency by Dr. med. Kai-Michael Hahn and Prof. Dr. med. Frank Strutz in issue 13/2024

As an addition to the well put together article we would have welcomed the important reference to the completely physiological age-dependent decline in the estimated glomerular filtration rate (eGFR) as calculated by means of the CKD-EPI equation (1, 2). As a rough equation, the loss of 1 mL/min/year from the 40th year of life can be assumed. This matters because—as correctly named—chronic kidney disease (CKD) is defined as a reading below 60 mL/min or albuminuria of above 30 mg/24 h. In this setting, disease is understood in the sense of illness, not “insufficiency” in the sense of “not sufficient.” In our opinion, in a scenario of an eGFR according to CKD-EPI of above 60 mL/min, applying the term “insufficiency” at stage G2 is very unfortunate (and for the formally renally healthy patients unnecessarily anxiety inducing). De facto we have been “drowning” for years in senseless referrals to nephrologists of older patients who are treated with angiotensin II receptor blockers or angiotensin converting enzyme inhibitors, but whose kidney function is entirely consistent with their age and who do not have microalbuminuria (3). In our view it would be important in this context to put into perspective creatinine blind ranges in terms of pathophysiology (“more than 50% of all nephrons are already destroyed if creatinine measurements are high”) and to include them on an age-adjusted basis in the table of the Kidney Disease: Improving Global Outcomes (KDIGO), as an 80 year old person who receives medication including, for example, an angiotensin II receptor blocker is allowed to have an age appropriate eGFR according to the CKD-EPI equation of 48–50 mL/min. The article correctly states that referral to a nephrologist is desirable from stage G3b or in albuminuria, but knowledge of the normal renal ageing process seems little know, at least in our catchment area.

DOI: 10.3238/arztebl.m2024.0161

Dr. med. Thomas Dietz, Nicola Riedel-Kusch, Christian Tschirch

Nierenzentrum Berlin

Conflict of interest statement

The authors declare that no conflict of interest exists.

References

1. Hahn KM, Strutz F: The early diagnosis and treatment of chronic renal insufficiency. Dtsch Arztebl Int 2024; 121: 428–35

2. Eriksen BO, Palsson R, Ebert N, et al.: GFR in healthy aging: an individual participant data meta-analysis of iohexol clearance in European population-based cohorts. J Am Soc Nephrol 2020; 31: 1602–15

3. Liu P, Quinn RR, Lam NN, et al.: Accounting for age in the definition of chronic kidney disease. JAMA Intern Med 2021; 181: 1359–66