Hypoglycemia (low blood glucose)

Chest | Endocrinology and Metabolism | Hypoglycemia (low blood glucose) (Disease)


Hypoglycemia (low blood sugar) is a commonly perceived problem. While some or many of the symptoms may be present, it is rarely confirmed or documented. Hypoglycemia most often affects those at the extremes of age, such as infants and the elderly, but may happen at any age. Generally, hypoglycemia is defined as a serum glucose level (the amount of sugar or glucose in your blood) below 70 mg/dL.

As a medical problem, hypoglycemia is diagnosed by the presence of three key features (known as Whipples triad). Whipples triad is (1) symptoms consistent with hypoglycemia; (2) a low plasma glucose concentration, and (3) relief of symptoms after the plasma glucose level is raised.

The body regulates its glucose level - the primary source of energy for the brain, muscles, and other essential cells - by the actions of different hormones. These hormones include insulin (which lowers the blood sugar level) and other chemicals which raise blood sugar (such as glucagon, growth hormone, and epinephrine).

The role of insulin is to help in the absorption of glucose from the blood by causing it to be stored in the liver or be transported into other tissues of the body (for metabolism or storage). Glucagon increases the amount of glucose in the blood by breaking down stored glucose (starch, called glycogen) and releasing it from the liver into the bloodstream.

Insulin and glucagon are usually correctly balanced if the liver and pancreas are functioning normally.

Symptoms of hypoglycemia typically appear at levels below 60 mg/dL. Some people may feel symptoms above this level. Levels below 50 mg/dL affect brain function.

Causes and Risk factors

Traditionally considered a stress hormone, epinephrine (or adrenalin) is made in the adrenal gland and in certain cells in the central nervous system. Epinephrine also elevates blood glucose levels by making glucose available for the body during a time of stress. When this mechanism is not working properly, hypoglycemia can result. Other hormones also help in raising the level of blood glucose, like cortisol made by the adrenal gland and growth hormone made by the pituitary gland.

Diagnosis and Treatment

Treatment ranges from a meal, oral glucose (sugar), glucagon, to intravenous glucose to raise the glucose level in the blood stream. The cause of the low blood sugar needs to be removed to prevent recurrence.