Q: What is the implication of 1.6 IgM, in the case of a person suffering from bone TB?

A:You are probably referring to an ELISA for IgM antibodies to tubercular antigens. TB serology has limited role in diagnosis of TB, though it does have a supportive role in diagnosing extra-pulmonary TB. A reading of 1.6 of IgM antibodies against TB bacilli is likely to be positive, but should be viewed in light of the controls during the test, and relevant clinical details.