Transient appearance of lactate dehydrogenase (LDH)-linked immunoglobulin and thyroid dysfunction at the postpartum period.

Here, we report a 28-year-old woman who transiently showed lactate dehydrogenase (LDH)-linked immunoglobulin during postpartum thyroiditis. She demonstrated high levels of serum LDH (794 IU/l) and thyroid hormones 7 months after delivery. Electrophoretic isoenzyme analysis of LDH showed an abnormal broadband caused by LDH-linked immunoglobulin (IgG-kappa). Transient thyrotoxicosis due to postpartum thyroiditis improved without any specific treatment, and elevated serum concentration of LDH decreased to the normal level (395 IU/l) with disappearance of LDH-linked IgG. LDH-linked immunoglobulin may also appear at the postpartum period.