Metabolic alkalosis is a condition that occurs when your blood becomes overly alkaline. Alkaline is the opposite of acidic.
Our bodies function best when the acidic-alkaline balance of our blood is just slightly tilted toward the alkaline.
Alkalosis occurs when your body has either:
- too many alkali-producing bicarbonate ions
- too few acid-producing hydrogen ions
Many people don’t experience any symptoms of metabolic alkalosis, so you may not know that you have it.
Metabolic alkalosis is one of the four main types of alkalosis. There are two kinds of metabolic alkalosis:
- Chloride-responsive alkalosis results from loss of hydrogen ions, usually by vomiting or dehydration.
- Chloride-resistant alkalosis results when your body retains too many bicarbonate (alkaline) ions, or when there’s a shift of hydrogen ions from your blood to your cells.
There’s also a condition called metabolic acidosis which occurs when your blood or fluids become overly acidic.
Your body compensates for both alkalosis and acidosis mainly through your lungs. The lungs change the alkalinity of your blood by allowing more or less carbon dioxide to escape as you breathe. The kidneys also play a role by controlling the elimination of bicarbonate ions.
Treatment is needed when these natural means of compensation aren’t enough.
Treatment for metabolic alkalosis depends on whether your alkalosis is
chloride-responsive or chloride-resistant. It also depends on the underlying cause of the alkalosis.
If you have only a mild chloride-responsive alkalosis, you may only need to make an adjustment in your diet, such as increasing your intake of salt (sodium chloride). The chloride ions will make your blood more acidic and reduce the alkalosis.
If your doctor determines your alkalosis needs immediate attention, they may give you an IV (intravenous drip) containing a saline solution (sodium chloride).
An IV is an almost painless procedure. It involves inserting a small needle into a vein in your arm. The needle is connected by a tube to a sterile bag containing salt dissolved in water. This is usually done in a hospital setting.
If you have chloride-resistant alkalosis, your body may be depleted of potassium. A sodium chloride solution won‘t help you and can make things worse. Your doctor will instead look for ways to increase potassium.
You can increase your potassium levels by:
- taking pills containing potassium chloride two to four times a day (under a doctor’s direction)
- receiving potassium chloride intravenously
Metabolic alkalosis may not show any symptoms. People with this type of alkalosis more often complain of the underlying conditions that are causing it. These can include:
- swelling in the lower legs (peripheral edema)
Severe cases of metabolic alkalosis can cause:
The severe symptoms are most common when the alkalosis is caused by chronic liver disease.
Two organs help to compensate for metabolic alkalosis — our lungs and our kidneys.
Our body produces carbon dioxide when we convert the food we eat into energy in our cells. The red blood cells in our veins take up the carbon dioxide and carry it to our lungs to be exhaled.
When the carbon dioxide gas mixes with the water in the blood, it forms a mild acid, called carbonic acid. The carbonic acid then breaks apart into the bicarbonate ion and hydrogen. Bicarbonate ions are alkaline.
By changing the rate of breathing, we can raise or lower the concentration of alkaline bicarbonate ions that are retained in our blood. The body does this automatically in the process called respiratory compensation. This is the body’s first and fastest response.
To compensate for alkalosis, signals are sent to slow the rate of respiration.
The kidneys can help combat alkalosis by increasing the excretion of bicarbonate ions through the urine. This is also an automatic process, but it’s slower than respiratory compensation.
Several different underlying conditions can cause metabolic alkalosis. These include:
Loss of stomach acids. This is the most common cause of metabolic alkalosis. It’s usually brought on by vomiting or suction through a nose-feeding tube.
The gastric juices have a high content of hydrochloric acid, a strong acid. Its loss causes an increase in the alkalinity of the blood.
The vomiting can result from any number of stomach disorders. By figuring out and treating the cause of the vomiting, your doctor will cure the metabolic alkalosis.
Excess of antacids. Antacid use won’t normally lead to metabolic alkalosis. But if you have weak or failing kidneys and use a nonabsorbable antacid, it can bring on alkalosis. Nonabsorbable antacids contain aluminum hydroxide or magnesium hydroxide.
Diuretics. Some diuretics (water pills) commonly prescribed for high blood pressure can cause increased urinary acid secretion. The increased secretion of acid in the urine can make your blood more alkaline.
If alkalosis shows up when you’re taking drugs such as thiazide or loop diuretics, your doctor may ask you to stop.
Potassium deficiency (hypokalemia). A deficiency of potassium can cause the hydrogen ions normally present in the fluid around your cells to shift inside the cells. The absence of acidic hydrogen ions causes your fluids and blood to become more alkaline.
Reduced volume of blood in the arteries (EABV). This can come from both a weakened heart and from cirrhosis of the liver. A reduced blood flow impairs your body’s ability to remove the alkaline bicarbonate ions.
Heart, kidney, or liver failure. Metabolic alkalosis can be caused by failure of a major organ, such as your heart, kidney, or liver. This leads to potassium depletion.
A standard saline solution (sodium chloride) can make things worse by causing your body to retain fluids without getting rid of the excess of bicarbonate ions that are causing the alkalosis.
Genetic causes. In rare cases, an inherited gene can be the cause of metabolic alkalosis. Five inherited diseases that can cause metabolic alkalosis are:
- Bartter syndrome
- Gitelman syndrome
- Liddle syndrome
- glucocorticoid remediable aldosteronism
- apparent mineralocorticoid excess
To begin diagnosis, your doctor will take your medical history and give you a physical examination.
If they suspect alkalosis, they’ll have your blood and urine tested. They’ll look at the levels of oxygen and carbon dioxide in your arteries and measure the acidity and alkalinity of your blood.
Understanding pH levels
The acidity or alkalinity of a liquid is measured on a scale called pH. In metabolic alkalosis, the pH of your blood is high.
The most neutral substance, water, has a pH of 7. When the pH of a liquid falls below 7, it becomes acidic. When it rises above 7, it’s alkaline.
Your blood normally has a pH from 7.35 to 7.45, or slightly alkaline. When the pH rises significantly above this level, you have metabolic alkalosis.
Your doctor may also test for the concentrations of chloride and potassium ions in your urine.
When the chloride level is low, it indicates that you may respond to treatment with a saline solution. A low potassium concentration can indicate either potassium deficiency or overuse of laxatives.
Hypochloremia means you have too little of the chloride ion in your blood.
Hypochloremic alkalosis is a serious condition that can put you into shock. It can result from dehydration and other causes.
Fortunately, it can be treated by a standard saline (salt) solution. This can be delivered by IV if you have a severe case, or by adjustments to your diet in mild cases.
Metabolic alkalosis most commonly results from severe cases of vomiting that cause you to lose the acidic fluids in your stomach. This can usually be reversed by treatment with a saline solution.
It can also be the result of a potassium deficiency or a chloride deficiency. These deficiencies can be treated with intravenous fluids or, in mild cases, with a diet adjustment.
Some cases of alkalosis are caused by serious underlying heart, kidney, or liver conditions. While the alkalosis can often be reversed in the short term, the underlying condition has to be treated for a lasting cure.
See your doctor if you’re experiencing any new or enduring symptoms.