Autoimmune fatigue syndrome (AIFS) is defined by chronic nonspecific complaints, a positive antinuclear antibody (ANA) assay, and the absence of another explanation for the complaints. Some severe cases fulfill the criteria for chronic fatigue syndrome (CFS). CFS is a syndrome characterized by disabling severe fatigue and defined by the criteria proposed by the U.S. Centers for Disease Control and Prevention. In this report, a patient with chronic fatigue syndrome and positive ANA assay was described as having developed postpartum thyroiditis 5 years after the onset. Subchemical hypothyroidism is characterized by clinical hypothyroidism not meeting biochemical criteria but showing evidence of thyroid autoimmunity. The relation between AIFS and subchemical hypothyroidism is discussed.
