Kotzmann et al. (58) described an increased CD4:CD8 T-cell ratio in patients with primary hyperparathyroidism, characterized by increased serum interleukin (IL)-6 and IL-17A levels (59, 60), and in mice, PTH augmented the production of tumor necrosis factor-α (TNF-α) by T cells. This evidence concerns the gene TNF and primary hyperparathyroidism.