Table 4. Relevant confounders that limit creatinine measurement accuracy according to manufacturer’s test manuals for the enzymatic (creatinine-E) and Jaffé assay (creatinine-J).

Relevant influences	Creatinine-E measurement	Creatinine-J measurement
Icterus	• Values above 257 µmol/L (15 mg/dl) for conjugated bilirubin and above 342 µmol/L (20 mg/dl) for unconjugated bilirubin [18]	• Values above 86 µmol/L (5 mg/dl) for conjugated bilirubin and above 171 µmol/L (10 mg/dl) for unconjugated bilirubin [18]
Hemolysis	• Values above 497 µmol/L (800 mg/dl) for hemoglobin [18]	• Values above 621 µmol/L (1,000 mg/dl) for hemoglobin [18]
	• HbF values above 600 mg/dl [19]	• HbF values above 60 mg/dl [19]
Lipemia	• L-index* above 2,000 [18]	• L-index* above 800 [18]
Medication:
• Incorrect low	• Rifampicin
	• Levodopa
	• Calcium Dobesilate
• Incorrect high	• DL-Proline values above 1 mmol/l (115 mg/l)	• Cefoxitin
	• N-Ethylglycine
• Both directions	• Ascorbic acid values above 1,70 mmol/l (300 mg/dl)	• Cyanokit (hydroxocobalamine) [20], [21]
	• Phenindione [20], [21]
Ketones	• No influence	• Influence due to pseudo-creatinine chromogens [22]
Others	• Rarely gammopathy (especially type M, Waldenström’s macroglobulinemia) may influence both measurement methods

*The L-index corresponds to the blur of the probe. There is no exact correlation with the triglyceride concentration.