Effect of acetylsalicylic acid on renal function in systemic lupus erythematosus

Comparison between IDMS-traceable Jaffe and enzymatic creatinine assays for estimation of glomerular filtration rate by the CKD-EPI equation in healthy and diabetic subjects

OBJECTIVES

The aim of this paper was to compare the agreement between creatinine measured by Jaffe and enzymatic methods and their putative influence on eGFR as calculated by the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation in healthy and diabetic individuals.

DESIGN AND METHODS

Cross-sectional study conducted in 123 adult southern Brazilians with GFR>60 mL/min/1.73 m² (53 patients with type 2 diabetes, 70 healthy volunteers). Mean age was 49±16 years (range of 19-86). Most were female (55%) and white (83%). Creatinine was measured by a traceable Jaffe method (Modular P, Roche Diagnostic) and by an enzymatic method (CREA plus, Roche/Hitachi 917). GFR was measured by the ⁵¹Cr-EDTA single-injection method.

RESULTS

Serum creatinine measured by the Jaffe and enzymatic methods was similar in healthy subjects (0.79±0.16 vs. 0.79±0.15 mg/dL, respectively, P=0.76), and diabetic patients (0.96±0.22 vs. 0.92±0.29 mg/dL, respectively, P=0.17). However, the correlation between the two methods was higher in the healthy group (r=0.90 vs. 0.76, P<0.001). The difference between Jaffe creatinine and enzymatic creatinine was <10% in 63% of cases in the healthy group and 40% of cases in the diabetes group (P=0.018). In the subset of patients with diabetes, eGFR based on enzymatic assay results showed better agreement with measured GFR than did eGFR based on Jaffe results.

CONCLUSION

Jaffe and enzymatic creatinine methods show adequate agreement in healthy subjects, but in the presence of diabetes, the enzymatic method performed slightly better.

A rise in plasma creatinine that is not a sign of renal failure: which drugs can be responsible?

This is a review of the available information about drugs which cause an increase in plasma creatinine concentration without decreasing glomerular filtration rate (GFR). The GFR is the main, but not the single, determinant of the plasma creatinine levels. Several drugs, such as cimetidine, trimethoprim, corticosteroids, pyrimethamine, phenacemide, salicylates and active vitamin D metabolites, have been reported to increase plasma creatinine without influencing its glomerular filtration. Cimetidine, trimethoprim, pyrimethamine and salicylates can inhibit secretion of creatinine by the proximal tubule. Corticosteroids and vitamin D metabolites probably modify the production rate and the release of creatinine. The exact mechanism of phenacemide-creatinine interaction is not fully explained. These drug-induced alterations in plasma creatinine concentration have clinical significance when GFR is estimated by using plasma creatinine.

Therapeutic uses of aspirin in renal diseases

Inhibition, by aspirin, of platelet aggregation, prostaglandin synthesis, smooth muscle cell proliferation, and thromboxane genesis has potential therapeutic uses in renal diseases. Clinically, some benefit from aspirin has been shown in some forms of glomerulonephritis but not in others, such as renovascular hypertension, pregnancy-induced hypertension, and diabetic nephropathy. Experimentally, aspirin aided in amelioration of cyclosporine toxicity and in preservation of explanted kidneys being prepared for transplantation.