Impact of creatinine methodology on glomerular filtration rate estimation in diabetes

The Patient and Treatment Characteristics of Kidney Transplant Recipients with a Clinically Relevant Jaffe/Enzymatic Serum Creatinine Difference

Background: Differences in serum creatinine (SCr) between the Jaffe and enzymatic methods affect the detection and staging of chronic kidney disease in kidney transplant recipients (KTRs). However, there are very limited data on the extent to which the detection of acute kidney injury (AKI) is affected, what impact immunosuppression can have and whether a KTR-specific estimated glomerular filtration rate (eGFR) formula is beneficial. Methods: A total of 12,081 parallel Jaffe/enzymatic SCr (eSCr) measurements of adult outpatient KTRs (61% male, median age 53 years) in the same serum sample at the University Hospital Essen (Germany) between January 2020 and October 2023 were evaluated. AKI and CKD were defined according to current KDIGO guidelines. The GFR was estimated using CKD-EPI and KTR-specific formulas. Results: In about 1% of all measurements and 5% of the KTR patients, the SCr difference between the two methods was ≥ 0.3 mg/dl. A total of 81% of these patients were male; the median age was 52 years. High levels of immunosuppression, including when Belatacept was used, did not seem to have a clinically relevant impact on the difference between Jaffe and eSCr. The KTR-specific eGFR formula generally showed a greater agreement between Jaffe and eSCr than the CKD-EPI eGFR formula, but they showed differences in the classification of CKD stages, especially in less severe stages. Conclusions: Clinically relevant SCr differences between Jaffe and SCr are rare and depend on the type of immunosuppression. A KTR-specific eGFR formula could be beneficial in some cases, but there are limitations in less severe CKD stages.

Effect of Difference in Serum Creatinine between Jaffe and Enzymatic Methods in Outpatient Kidney Transplant Recipients

Background: Deviations in serum creatinine (SCr), due to its determination using a Jaffe or an enzymatic method, have an effect on kidney disease detection and staging. It is not yet clear how large this effect is in kidney transplant recipients (KTRs). SCr measurement differences are of particular importance here to evaluate the graft function. Methods: The results of all parallel SCr measurements (Jaffe and enzymatic method) of adult outpatient KTRs in the same serum sample at the University Hospital Essen (Germany) between January 2020 and October 2023 were evaluated. A Bland-Altman plot with 95% limits of agreement (LoA) was used to assess the difference between the Jaffe and the enzymatic SCr (eSCr). For all patients, we used the CKD-EPI 2009 and EKFC formula, and for patients ≥ 70 years, we also used the BIS1 formula for the determination of eGFR. Results: A total of 12,081 parallel SCr measurements from 1243 KTRs were analyzed, where 61% were male and the median age was 53 years. On average, Jaffe SCr was 0.03 mg/dL higher than eSCr (LoA -0.16; 0.21 mg/dL). On average, the eGFR determined by Jaffe SCr was 1.9 mL/min/1.73 m2 lower than the eGFR determined by eSCr (LoA -9.5; 5.7 mL/min/1.73 m2). The comparison of eGFR between the two SCr methods revealed a different CKD stage in 1589 (13%) of all analyzed measurements, most frequently between G2/G3a (41%) and G3a/G3b (24%). When using the EKFC and BIS1 formulas, there were approximately the same number of measurements leading to a different CKD stage. Conclusions: In more than every tenth SCr determination in outpatient KTRs, the difference between the Jaffe and enzymatic methods had an influence on the assignment to a CKD stage. This effect was comparably pronounced for all eGFR formulas applied.

Effect of serum creatinine difference between the Jaffe and the enzymatic method on kidney disease detection and staging

Background

Serum creatinine (SCr), mainly determined by the Jaffe or an enzymatic method, is the central marker to assess kidney function. Deviations between these two methods may affect the diagnosis and staging of acute kidney injury (AKI) and chronic kidney disease (CKD).

Methods

The results of the first parallel SCr measurement (Jaffe and enzymatic method) of adult in- and outpatients in the same serum sample at the University Hospital Essen (Essen, Germany) between 2020-2022 were retrospectively evaluated. A Bland-Altman plot with 95% limits of agreement (LoAs) was used to assess the difference between the Jaffe and the enzymatic SCr (eSCr) method. We used the 2009 Chronic Kidney Disease Epidemiology Collaboration equation for determination of estimated glomerular filtration rate (eGFR) according to the Kidney Disease: Improving Global Outcomes guidelines.

Results

A total of 41 144 parallel SCr measurements were evaluated. On average, Jaffe SCr was 0.07 mg/dl higher than eSCr (LoA -0.12; 0.25 mg/dl). In 19% of all cases there was a different CKD stage when comparing eGFR between both SCr methods, of which 98% resulted in a more severe CKD stage determined with Jaffe SCr. In 1.6% of all cases Jaffe SCr was ≥0.3 mg/dl higher than eSCr.

Conclusion

The present study showed that methods of SCr measurement may affect both the diagnosis and staging of AKI and CKD. This must be taken into account when interpreting measurements of renal function in everyday clinical practice, but also when planning and comparing studies on renal diseases. One should therefore stay with one method for SCr measurement, preferably with the enzymatic method.

Diagnostic challenges of diabetic kidney disease

Diabetic kidney disease (DKD) is one of the most common microvascular complications of both type 1 and type 2 diabetes and the most common cause of the end-stage renal disease (ESRD). It has been evidenced that targeted interventions at an early stage of DKD can efficiently prevent or delay the progression of kidney failure and improve patient outcomes. Therefore, regular screening for DKD has become one of the fundamental principles of diabetes care. Long-established biomarkers such as serum-creatinine-based estimates of glomerular filtration rate and albuminuria are currently the cornerstone of diagnosis and risk stratification in routine clinical practice. However, their immanent biological limitations and analytical variations may influence the clinical interpretation of the results. Recently proposed new predictive equations without the variable of race, together with the evidence on better accuracy of combined serum creatinine and cystatin C equations, and both race- and sex-free cystatin C-based equation, have enabled an improvement in the detection of DKD, but also require the harmonization of the recommended laboratory tests, wider availability of cystatin C testing and specific approach in various populations. Considering the complex pathophysiology of DKD, particularly in type 2 diabetes, a panel of biomarkers is needed to classify patients in terms of the rate of disease progression and/or response to specific interventions. With a personalized approach to diagnosis and treatment, in the future, it will be possible to respond to DKD better and enable improved outcomes for numerous patients worldwide.

Comparison of glomerular filtration rate estimation using Jaffé and enzymatic creatinine assays in diabetic patients

BACKGROUND

Diabetic kidney disease (DKD) develops an end-stage renal failure and is a major cause of death in diabetic patients. A GFR below 60 ml/min per 1.73 m2 is one of the main markers of DKD. Therefore, the development of an accurate test for diagnosis and monitoring of the mentioned disease would be essential. Here, we examined the impacts of two different kits with different methods for creatinine measurement on the GFR values.

METHODS

Blood samples were collected from 80 diabetic patients referring to the clinical laboratory. The levels of serum creatinine were assessed using Jaffé and enzymatic assays by kits from two different manufacturers. Then to assess the eGFR levels, the MDRD equation was used. Further descriptive parameters of both methods and correlation of methods were also calculated.

RESULTS

Descriptive analysis of the data demonstrates a slight increase in the serum creatinine measured by Jaffé assay which leads to a substantial decrease in the levels of eGFR compared to the eGFR calculated by the enzymatic assay. Moreover, eGFR over 60 mL/min/1.73 m 2 in enzymatic assay was observed in 27.5% of participants while eGFR of the same participants was below 60 mL/min/1.73 m 2 when it was measured by Jaffé method. Consequently, 27.5% positive discordant cases were reported by Jaffé assay followed by misclassifying them as DKD patients compared with the enzymatic assay.

CONCLUSION

While using Jaffé assay, a low level of eGFR is observed which generates more misclassification into the DKD group and demands to an inclusive consideration by physicians in order to diagnose and monitor the DKD patients.

Chronic kidney disease and kidney health care status: the healthy life in Suriname (HeliSur) study

The high cardiovascular risk burden in low- and middle-income countries is expected to lead to an explosive increase in chronic kidney disease (CKD). However, population data on CKD from these countries are scarce. Therefore, we assessed kidney health in Suriname. In the Healthy Life in Suriname (HeliSur) study, a random sample of the adult population, we collected data with standardized questionnaires, physical examination, and blood and urine samples analysed in a central laboratory. Prevalent CKD was graded with KDIGO guidelines. In addition, we assessed national data on prevalent renal replacement therapy (RRT), estimated the future need for RRT, and evaluated national kidney health work force and policies. We include 1117 participants (2.0‰ of the population), 63% women, 40% of African ancestry and 43% of Asian ancestry, with a mean age of 42.2 (SE 0.4) years. Blood pressure is elevated in 72% of the participants, 26% have diabetes or prediabetes, and 78% are obese or overweight. The prevalence of CKD is 5.4%, and around 0.3% have kidney failure, translating to approximately 1500 patients nationally (2690 per million population, pmp), with currently 516 patients (920 pmp) on dialysis. Based on the participants from the random population sample in CKD stage G3 or G4, we estimate that 6750-10,750 pmp may develop kidney failure within the next 10 years. However, specialized kidney health workforce is currently very limited, and specific national or local policies for CKD management are lacking. Since the large majority of the general population has one or more risk factors for CKD including elevated blood pressure, urgent action is needed to strengthen kidney health care and prevent a catastrophic rise in need for RRT in the coming years.