In a case report, a 41-year-old woman with a 35-year history of type 1 diabetes and exertional angina pectoris was diagnosed with microvascular angina and started on L-arginine supplementation with 2 dietary bars a day ( HeartBar ), each containing L-arginine g. While consuming these dietary bars, the patient reported that her angina episodes disappeared and her exercise capacity increased. However, after 8 weeks of therapy, L-arginine supplementation was replaced with atorvastatin 40 mg daily because of availability issues with the supplement. The patient's angina episodes reemerged within 1 week and her exercise capacity worsened after 8 weeks. She was restarted on the L-arginine supplement with subsequent disappearance in angina symptoms, suggesting that L-arginine supplementation may be a potential treatment option for patients with diabetes mellitus suffering from microvascular angina. 71
As discussed in an earlier chapter, there are three iodothyronine deiodinases involved in the activation and inactivation of thyroid hormone. All three are coordinately regulated during gestation and function to closely regulate the supply of T3 to developing tissues while at the same time protecting the fetus against the effects of excess thyroid hormone. The physiological rationale for the maintenance of reduced circulating T3 concentrations throughout fetal life is still unknown, but it has been suggested that its function may be to avoid tissue thermogenesis and potentiate the anabolic state of the rapidly growing fetus while at the same time permitting highly regulated, tissue- specific maturation in an orderly, temporal sequence.