Metabolic alkalosis is characterized by a variation in the pH levels beyond the normal range of 7.35 – 7.45. It is a type of metabolic condition, which practically occurs due to decrease in the concentration of hydrogen ion.
Metabolic alkalosis does not present with any specific signs and symptoms. The symptoms which are experienced occur due to hypoventilation and hypokalemia which take place along with it. Due to hypokalemia, individuals often suffer from weakness, arrhythmias, polyuria and myalgia. When there is associated hypoventilation that occurs as compensatory mechanism, individuals suffer from muscle spasm, a short-lived tingling sensation that is short lived and jitteriness. In addition, there may be tremors in hands and light headedness, followed by confusion.
If the patient experiences seizures or has severe problems while breathing accompanied by loss of consciousness, he/she might need an emergency treatment. Such individuals should be immediately taken to emergency room for prompt medical action .
In the preliminary levels, serum electrolytes and arterial blood gas levels will be measured. Following this, a complete medical history should be taken in order to understand the etiology. If no history of medical condition is available, then it must be assumed that metabolic alkalosis is caused either due to diuretics, excessive vomiting, or mineralocorticoid excess . In order to uncover the exact cause, it is necessary to determine the concentration of urinary chloride.
In addition, the serum anion gap should also be calculated in order to distinguish between metabolic compensation and metabolic alkalosis . Along with all the above mentioned laboratory studies, it is necessary to conduct gene analysis to determine underlying conditions such as Bartter syndrome, Liddle's syndrome, Gitelman syndrome and glucocorticoid remediable aldosteronism.
Treatment of metabolic alkalosis depends on the underlying etiology, severity of condition and intravascular volume status of the individual. The aim of treatment is to increase the excretion of bicarbonates and simultaneously decrease its serum concentration.
In case of excessive vomiting, administration of antiemetics is indicated. Constant monitoring of the vital signs is also necessary. If metabolic alkalosis has occurred due to diuretics, the dosage needs to be adjusted accordingly. In such cases, acetazolamide or potassium sparing diuretics may be administered.
If situation demands the constant need for gastric suction, then the gastric secretion can be significantly reduced with the help of H2 blockers or proton – pump inhibitors .
It is also necessary to given intravenous administration of hydrochloric acid through the central line. This will correct chloride deficiency and thereby assist normalizing the pH levels. Once the alkalosis is corrected, it will cause improvement in peripheral oxygen unloading .
Prognosis of the condition depends on the underlying etiology and the extent of severity. When the condition is not appropriately treated, it can lead to development of arrhythmias and hypokalemia, and the patient can even enter in a comatose phase.
Kidney disorders can cause an increase in concentration of bicarbonates. Individuals taking diuretics are also likely to develop metabolic alkalosis. In addition to this, external loss of gastric secretion, such as vomiting, can also lead to development of metabolic acidosis.
Other causative factors include cystic fibrosis, loop diuretics, loss of colonic secretions and posthypercapnia. Short term metabolic acidosis will develop when an excess on an alkali is intravenously administered and the kidneys try to rapidly excrete bicarbonates .
Metabolic alkalosis is a common occurrence amongst hospitalized patients. It has been estimated that 50% of all acid base disorders is constituted by metabolic alkalosis. Mortality occurs in about 45% cases in which the pH measured is 7.55 and in about 80% in which the pH measures is more than 7.65 .
Under normal physiological conditions, the lungs along with the kidneys are responsible for the maintenance of the appropriate pH balance. Alkalosis develops when the carbon dioxide content decreases or concentration of bicarbonates increases.
In the condition of metabolic acidosis, the kidneys and gastrointestinal tract play a vital role. In hospitalized patients, sodium bicarbonate has to be given to patients but then it becomes difficult for the kidneys to excrete the excess of bicarbonates, and this leads to development of metabolic acidosis.
Loss of hydrogen ions is yet another phenomenon favoring increase in concentration of bicarbonates. During vomiting or nasogastric suction there is a loss of hydrogen ions, which in turn causes metabolic alkalosis to set in .
As a compensatory mechanism, the lungs slow down breathing to retain carbon dioxide and bring the condition back to normality. Such an event causes a decrease in pH levels, because the carbon dioxide is used for formation of intermediate carbonic acid. In addition to respiratory compensation, renal compensation also occurs, though it is less effective .
Effective management of underlying cause can help prevent onset of metabolic alkalosis. Individuals with healthy lungs and kidneys would generally not experience serious alkalosis. The condition is usually encountered in hospitalized patients. Therefore, carefully correction of the underlying etiology is necessary to prevent the onset of metabolic alkalosis.
Such a type of phenomenon causes increase in bicarbonate levels. In order to compensate for the increase in bicarbonate ions the arterial carbon dioxide rises due to development of alveolar hypoventilation. Bicarbonate concentration more than 35 mEq/L indicates onset of metabolic acidosis. Treating the underlying etiology can help in an effective management of the condition .
Definition: Metabolic alkalosis occurs as a result of increase in bicarbonate concentration that causes the pH level to rise beyond 7.45. Such a kind of event occurs due to loss of hydrogen ions that arises as consequence of various factors.
Cause: Several factors are known to play a role in causing metabolic alkalosis. It includes kidney diseases that causes improper excretion of excess of bicarbonates, diuretics, severe vomiting which results in loss of hydrogen ions and drugs which contain alkalotic agents. In addition, several disorders such as Liddle's syndrome, Gitelman syndrome, aminoglycoside toxicity and Bartter syndrome also favor the development of metabolic alkalosis.
Symptoms: Symptoms of metabolic alkalosis are associated with the secondary conditions like hypokalemia and hypoventilation. Signs and symptoms include weakness, polyuria, arrhythmias and myalgia. In addition, individuals can also experience tingling sensation, jitteriness and muscle spasms.
Diagnosis: A preliminary physical examination along with gathering of the past medial history is necessary. This is followed by measuring the arterial blood gases and serum electrolytes. Following this the serum anion gap is also calculated. Gene analysis is also indicated in determining several underlying conditions.
Treatment: Treatment is geared towards management of the underlying etiology. In the majority of cases, intravenous administration of hydrochloride is necessary. If medications are the cause, then either alternative drugs are prescribed or their dosage is adjusted.