Background: Chronic kidney disease (CKD) is an important but under-recognized condition. Recent national guidelines have recommended that biochemistry laboratories report estimated GFR (eGFR) to improve diagnosis of CKD and facilitate disease staging and management. Previous reports have suggested that intake of large amounts of cooked meat can lead to a significant increase in serum creatinine concentration.
Methods: Participants (n = 32), consisting of 17 healthy volunteers and 15 outpatients, were recruited. Measurement of serum creatinine (kinetic Jaffe method, enzymatic, isotope-dilution mass spectrometry [IDMS]) and cystatin C, and calculation of eGFR were carried out before (i) and after a meal containing cooked meat (ii) and a meat-free meal (iii).
Results: Following intake of cooked meat, median serum creatinine concentration (kinetic Jaffe) increased from 80.5 micromol/L preprandially to 101.0 micromol/L 1-2 h postprandially (P<0.0001), and 99.0 micromol/L 3-4 h postprandially (P<0.0001). Median eGFR decreased from 84.0 mL/min/1.73 m2 preprandially to 59.5 mL/min/1.73 m2 1-2 h postprandially (P<0.0001), and 64.0 mL/min/1.73 m2 3-4 h postprandially (P<0.0001). Consumption of non-meat-containing meals had little impact on serum creatinine (kinetic Jaffe) and eGFR. Changes in serum creatinine were similar using all three methods, and cystatin C concentration was generally uninfluenced by food intake.
Conclusions: Intake of cooked meat has a significant effect on serum creatinine concentration and eGFR. Misclassification of CKD is possible if measurements are made after meals containing cooked meat. Clinicians should ensure that CKD classification is based on samples taken in the appropriate conditions: either fasting or after avoidance of cooked meat on the day of sampling. National guidelines which overlook this factor should be revisited.