This test is difficult to perform, and often requires a trained observer.
Pri ravneh med 415 in 530 μmol/L (7 in 8,9 mg/dL) znaša tveganje 0,5 % na leto, pri osebah z ravnjo nad 535 μmol/L (9 mg/dl) pa gre za riziko 4,5 % na leto.