TPH1 and hyperinsulinemic hypoglycemia, familial, 4: On the base of the result of our study of a greater risk of TPH in pre-operative deficiency and normal 25(OH)D groups than in insufficiency, only patients with pre-operative 25(OH)D deficiency and high PTH levels might benefit from mild preoperative 25(OH)D supplementation, in order to bring 25(OH)D from a deficiency to insufficiency, but not normal level.