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August 7, 1972

Infectious and Serum Viral HepatitisDifferentiation With Serum IgM and Thymol Turbidity as Criteria

JAMA. 1972;221(6):571-575. doi:10.1001/jama.1972.03200190017004

Serum levels of IgM and thymol turbidity were determined in 31 patients with Australia antigen-negative, documented short-incubation infections with the infectious hepatitis (IH) virus, and 65 patients with Australia antigen-positive, long-incubation serum hepatitis (SH) infections. During the acute phase, IgM and thymol turbidity levels were significantly higher in patients with IH than in those with SH infections. However, the overlap was so great that neither test clearly distinguished between the two groups. Following recovery in both groups, IgM level usually returned to normal, but the thymol turbidity level often remained elevated. Of patients with prolonged active SH hepatitis, only half had raised levels of IgM and thymol turbidity. We conclude that neither the IgM level nor the thymol turbidity level clearly distinguishes between IH and SH infections or provides a reliable index of disease activity.