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Hypoglycemia

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Hypoglycemia, or low blood glucose, causes cardiovascular physiological effects as a result of the sympathoadrenal system. These effects include an increased heart rate, increased heart contractility, and decreased peripheral arterial resistance. Together, these increase peripheral blood pressure, but decrease central blood pressure. This can have larger effects on those with diabetes. Hypoglycemia may cause greater arterial wall stiffness and less elasticity, which in turn reflects blood pressure and increases the heart’s workload.[1] Symptoms of hypoglycemia related to the symapthoadrenal system include anxiety, tremors, irregular heartbeat, sweating, hunger, and paresthesia. Hypothermia and neurological deficits can also occur while permanent brain damage is uncommon. The activation of the system is assisted by norepinephrine, acetylcholine, and epinephrine. Hypoglycemia unawareness can occur because the symapthoadrenal system response is reduced, in turn, the symptoms are reduced. Since the symptoms go unnoticed, this may lead to a dangerous cycle of hypoglycemia and an increased risk of severe hypoglycemia.[2]

Insulin is essential in triggering the sympathoadrenal system (the release of norepinephrine and epinephrine) to respond to hypoglycemia, which then raises glucagon levels. The insulin present in the brain acts on the central nervous system by crossing the blood-brain barrier and affecting the sympathetic nervous system. Thereby, helping to initiate a response to hypoglycemia through the sympathoadrenal system.[3] Individuals with hypoglycemia should self-monitor their blood glucose level and can take glucose in the forms of tablets or foods high in glucose. Parenteral therapy may be necessary for severe hypoglycemia.[4] Hypoglycemia- associated autonomic failure (HAAF) can occur if left untreated. The sympathoadrenal system activity is significantly reduced because the changed gylcemic threshold allows for lower glucose concentrations. Glucose cannot effectively regulate itself, decreasing epinephrine responses.[5]

Phaeochromocytoma

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Phaeochromocytoma are rare tumors that secrete catecholamines and affect the sympathoadrenal system. They are typically found inside the adrenal medulla, but can also be present right outside adrenal medulla in tissue. Symptoms include headaches, sweating, palpitations, hypertension, hypoglycemia, anxiety, weight loss, fever, nausea, and cardiovascular complications. Phaeochromocytoma can be treated through removal of the tumor and should be done in a timely manner. On average, there is a delay of three years between initial symptoms and diagnosis because the tumors are hard to find and the symptoms are highly variable and very common in other diseases.[6]

  1. ^ Yang, Shi-Weg; Park, Kyoung- Ha; Zhou, Yu-Jie (2015). "The Impact of Hypoglycemia on the Cardiovascular System: Physiology and Pathophysiology". Angiology. doi:10.1177/0003319715623400.
  2. ^ Cryer, Phillip; Davis, Stephen; Shamoon, Hary (2003). "Hypoglycemia in Diabetes". Diabetes Care. 26 (6): 1902-1912. doi:10.2337/diacare.26.6.1902.
  3. ^ Fisher, Simon; Brüning, Jens; Lannon, Scott; Kahn, C. (2005). "Insulin Signaling in the Central Nervous System Is Critical for the Normal Sympathoadrenal Resonse to Hypoglycemia". Diabetes Care. 54 (4): 1447-1451. doi:10.2337/diabetes.54.5.1447.
  4. ^ Cryer, Phillip; Davis, Stephen; Shamoon, Hary (2003). "Hypoglycemia in Diabetes". Diabetes Care. 26 (6): 1902-1912. doi:10.2337/diacare.26.6.1902.
  5. ^ Cryer, Phillip (2006). "Mechanisms of sympathoadrenal failure and hypoglycemia in diabetes". Journal of Clinical Investigation. 116 (6): 1470-1473. doi:10.1172/JCI28735.
  6. ^ Lenders, Jacques; Graeme, Eisenhofer; Massimo, Mannelli; Pacak, Karel (2005). "Phaeochromocytoma". The Lancet. 366 (9486): 665-675. doi:10.1016/S0140-6736(05)67139-5.