Of these 5 cases, 2 received pituitary surgery after the initial TRH test, but before the start of thyroid replacement therapy, whereas 3 cases (7.1%) spontaneously developed CH after a mean of 2.8 years ±1.4 years and 8 patients (19.0%) were lost in follow-up. This evidence concerns the gene TRH and cyclic hematopoiesis.