Alkalosis is the result of a process reducing hydrogen ion concentration of arterial blood plasma (alkalemia). In contrast to acidemia (serum pH 7.35 or lower), alkalemia occurs when the serum pH is higher than normal (7.45 or higher). Alkalosis is usually divided into the categories of respiratory alkalosis and metabolic alkalosis or a combined respiratory/metabolic alkalosis.
Signs and symptoms
Metabolic alkalosis is usually accompanied by low blood potassium concentration, causing, e.g., muscular weakness, muscle pain, and muscle cramps (from disturbed function of the skeletal muscles), and muscle spasms (from disturbed function of smooth muscles).
It may also cause low blood calcium concentration. As the blood pH increases, blood transport proteins, such as albumin, become more ionized into anions. This causes the free calcium present in blood to bind more strongly with albumin. It may cause tetany in severe cases.
Causes
Respiratory alkalosis is caused by hyperventilation, resulting in a loss of carbon dioxide. Compensatory mechanisms for this include release of hydrogen ion from tissue buffers and excretion of bicarbonate in the kidneys, both of which lower blood pH. Hyperventilation-induced alkalosis can be seen in several deadly central nervous system diseases such as strokes or Rett syndrome. During exercise, due to the inability to utilize muscle glycogen as a substrate for ATP synthesis, plasma lactate does not significantly rise (and may fall below) compared to resting levels; consequently, McArdle disease individuals do not experience lactic acidosis. increased epinephrine, and/or increased oxygen demand for oxidative phosphorylation of blood borne substrates (free fatty acids and blood glucose).