Metabolic Alkalosis: Practice Essentials, Pathophysiology, Etiology
Author: Christie P Thomas, MBBS, FRCP, FASN, FAHA; Chief Editor: Vecihi Batuman, MD, FASN more... Metabolic alkalosis is a primary increase in serum bicarbonate (HCO3-) concentration. This occurs as a consequence of a loss of H+ from the body or a gain in HCO3-. In its pure form, it manifests as alkalemia (pH >7.40). As a compensatory mechanism, metabolic alkalosis leads to alveolar hypoventilation with a rise in arterial carbon dioxide tension (PaCO2), which diminishes the change in pH that would otherwise occur. Normally, arterial PaCO2 increases by 0.5-0.7 mm Hg for every 1 mEq/L increase in plasma bicarbonate concentration, a compensatory response that is very quick. If the change in PaCO2 is not within this range, then a mixed acid-base disturbance occurs. For example, if the increase in PaCO2 is more than 0.7 times the increase in bicarbonate, then metabolic alkalosis coexists with primary respiratory acidosis. Likewise, if the increase in PaCO2 is less than the expected change, then a primary respiratory alkalosis is also present. The first clue to metabolic alkalosis is often an elevated bicarbonate concentration that is observed when serum electrolyte measurements are obtained. Remember that an elevated serum bicarbonate concentration may also be observed as a compensatory response to primary respiratory acidosis. However, a bicarbonate concentration greater than 35 mEq/L is almost always caused by metabolic alkalosis. Metabolic alkalosis is diagnosed by measuring serum electrolytes and arterial blood gases . If the etiology of metabolic alkalosis is not clear from the clinical history and physical examination, including drug use and the presence of hypertension, then a urine chloride ion concentration can be obtained. Calculation of the serum anion gap may al Continue reading >>
26.5 Disorders Of Acid-base Balance Anatomy And Physiology
Glycolic acid, and some oxalic and formic acids* The first three of the eight causes of metabolic acidosis listed are medical (or unusual physiological) conditions. Strenuous exercise can cause temporary metabolic acidosis due to the production of lactic acid. The last five causes result from the ingestion of specific substances. The active form of aspirin is its metabolite, sulfasalicylic acid. An overdose of aspirin causes acidosis due to the acidity of this metabolite. Metabolic acidosis can also result from uremia, which is the retention of urea and uric acid. Metabolic acidosis can also arise from diabetic ketoacidosis, wherein an excess of ketones is present in the blood. Other causes of metabolic acidosis are a decrease in the excretion of hydrogen ions, which inhibits the conservation of bicarbonate ions, and excessive loss of bicarbonate ions through the gastrointestinal tract due to diarrhea. Metabolic Alkalosis: Primary Bicarbonate Excess Metabolic alkalosis is the opposite of metabolic acidosis. It occurs when the blood is too alkaline (pH above 7.45) due to too much bicarbonate (called primary bicarbonate excess). A transient excess of bicarbonate in the blood can follow ingestion of excessive amounts of bicarbonate, citrate, or antacids for conditions such as stomach acid refluxknown as heartburn. Cushings disease, which is the chronic hypersecretion of adrenocorticotrophic hormone (ACTH) by the anterior pituitary gland, can cause chronic metabolic alkalosis. The oversecretion of ACTH results in elevated aldosterone levels and an increased loss of potassium by urinary excretion. Other causes of metabolic alkalosis include the loss of hydrochloric acid from the stomach through vomiting, potassium depletion due to the use of diuretics for hypertension, and Continue reading >>
Alkalosis
The kidneys and lungs maintain the proper balance (proper pH level) of chemicals called acids and bases in the body. Decreased carbon dioxide (an acid) level or increased bicarbonate (a base) level makes the body too alkaline, a condition called alkalosis. There are different types of alkalosis. These are described below. Respiratory alkalosis is caused by a low carbon dioxide level in the blood. This can be due to: Fever Being at a high altitude Lack of oxygen Liver disease Metabolic alkalosis is caused by too much bicarbonate in the blood. It can also occur due to certain kidney diseases. Hypochloremic alkalosis is caused by an extreme lack or loss of chloride, such as from prolonged vomiting. Hypokalemic alkalosis is caused by the kidneys' response to an extreme lack or loss of potassium. This can occur from taking certain water pills (diuretics). Compensated alkalosis occurs when the body returns the acid-base balance to normal in cases of alkalosis, but bicarbonate and carbon dioxide levels remain abnormal. Continue reading >>
Acid-base Disorders
Content currently under development Acid-base disorders are a group of conditions characterized by changes in the concentration of hydrogen ions (H+) or bicarbonate (HCO3-), which lead to changes in the arterial blood pH. These conditions can be categorized as acidoses or alkaloses and have a respiratory or metabolic origin, depending on the cause of the imbalance. Diagnosis is made by arterial blood gas (ABG) interpretation. In the setting of metabolic acidosis, calculation of the anion gap is an important resource to narrow down the possible causes and reach a precise diagnosis. Treatment is based on identifying the underlying cause. Continue reading >>
Acid-base Disturbances In Children, Acidosis, Alkalosis
Acid-base disturbances in children, Acidosis, Alkalosis Acid-base disturbances in children, Acidosis, Alkalosis The pH of the blood is controlled via three systems: chemical buffering, respiratory function, and renal function. Acidosis means a clinical disturbance in which there is an increase in plasma acidity, whether due to increased production by the tissues, loss of buffering ability or decreased clearance by the kidneys. A multitude of problems, congenital and acquired, can result in metabolic acidosis. The hallmark of a metabolic acidosis is a low serum HCO3 level. Metabolic alkalosis means the patient has an elevated HCO3, most typically seen with administration of loop diuretics. A respiratory acidosis means an increase in the partial pressure of carbon dioxide in the blood (PaCO2) due to inadequate respiration. Respiratory alkalosis typically occurs in response to a metabolic stimulus, such as hyperammonemia (seen in urea cycle defects) or diabetic ketoacidosis (DKA). Metabolic and respiratory mechanisms affect the acid-base state. The relationship between the pH and PaCO2 is dependent upon the plasma bicarbonate-plasma carbonic acid pool. To estimate the effect of pH change, for every 10 mmHg PaCO2, the pH will change by approximately 0.08; for example, if the PaCO2 rises to 50 from a normal 40 mmHg, then the expected pH will be approximately 7.32, or decreased by 0.08. Comparison of the base excess with the reference range assists in determining whether an acid-base disturbance is caused by a respiratory, metabolic or mixed metabolic/respiratory problem. While CO2 defines the respiratory component of acid-base balance, base excess defines the metabolic component. To generalize, a metabolic acidosis will have a low serum HCO3 and a respiratory acidosis will Continue reading >>
Disorders Of Acid-base Balance
Module 10: Fluid, Electrolyte, and Acid-Base Balance By the end of this section, you will be able to: Identify the three blood variables considered when making a diagnosis of acidosis or alkalosis Identify the source of compensation for blood pH problems of a respiratory origin Identify the source of compensation for blood pH problems of a metabolic/renal origin Normal arterial blood pH is restricted to a very narrow range of 7.35 to 7.45. A person who has a blood pH below 7.35 is considered to be in acidosis (actually, physiological acidosis, because blood is not truly acidic until its pH drops below 7), and a continuous blood pH below 7.0 can be fatal. Acidosis has several symptoms, including headache and confusion, and the individual can become lethargic and easily fatigued. A person who has a blood pH above 7.45 is considered to be in alkalosis, and a pH above 7.8 is fatal. Some symptoms of alkalosis include cognitive impairment (which can progress to unconsciousness), tingling or numbness in the extremities, muscle twitching and spasm, and nausea and vomiting. Both acidosis and alkalosis can be caused by either metabolic or respiratory disorders. As discussed earlier in this chapter, the concentration of carbonic acid in the blood is dependent on the level of CO2 in the body and the amount of CO2 gas exhaled through the lungs. Thus, the respiratory contribution to acid-base balance is usually discussed in terms of CO2 (rather than of carbonic acid). Remember that a molecule of carbonic acid is lost for every molecule of CO2 exhaled, and a molecule of carbonic acid is formed for every molecule of CO2 retained. Figure 1. Symptoms of acidosis affect several organ systems. Both acidosis and alkalosis can be diagnosed using a blood test. Metabolic Acidosis: Primary Bic Continue reading >>
Alkalosis
Your blood is made up of acids and bases. The amount of acids and bases in your blood can be measured on a pH scale. It’s important to maintain the correct balance between acids and bases. Even a slight change can cause health problems. Normally, your blood should have a slightly higher amount of bases than acids. Alkalosis occurs when your body has too many bases. It can occur due to decreased blood levels of carbon dioxide, which is an acid. It can also occur due to increased blood levels of bicarbonate, which is a base. This condition may also be related to other underlying health issues such as low potassium, or hypokalemia. The earlier it’s detected and treated, the better the outcome is. Acid-base balance » There are five main types of alkalosis. Respiratory alkalosis Respiratory alkalosis occurs when there isn’t enough carbon dioxide in your bloodstream. It’s often caused by: hyperventilation, which commonly occurs with anxiety high fever lack of oxygen salicylate poisoning being in high altitudes Metabolic alkalosis Metabolic alkalosis develops when your body loses too much acid or gains too much base. This can be attributed to: excess vomiting, which causes electrolyte loss overuse of diuretics a large loss of potassium or sodium in a short amount of time antacids accidental ingestion of bicarbonate, which can be found in baking soda laxatives alcohol abuse Hypochloremic alkalosis Hypochloremic alkalosis occurs when there’s a significant decline of chloride in your body. This can be due to prolonged vomiting or sweating. Chloride is an important chemical needed to maintain balance in bodily fluids, and it’s an essential part of your body’s digestive fluids. Hypokalemic alkalosis Hypokalemic alkalosis occurs when your body lacks the normal amount Continue reading >>
Metabolic Alkalosis - Endocrine And Metabolic Disorders - Merck Manuals Professional Edition
(Video) Overview of Buffering and the Henderson-Hasselbalch Equation By James L. Lewis, III, MD, Attending Physician, Brookwood Baptist Health and Saint Vincents Ascension Health, Birmingham Metabolic alkalosis is primary increase in bicarbonate (HCO3) with or without compensatory increase in carbon dioxide partial pressure (Pco2); pH may be high or nearly normal. Common causes include prolonged vomiting, hypovolemia, diuretic use, and hypokalemia. Renal impairment of HCO3 excretion must be present to sustain alkalosis. Symptoms and signs in severe cases include headache, lethargy, and tetany. Diagnosis is clinical and with arterial blood gas and serum electrolyte measurement. The underlying condition is treated; oral or IV acetazolamide or hydrochloric acid is sometimes indicated. Metabolic alkalosis is bicarbonate (HCO3) accumulation due to Intracellular shift of hydrogen ion (H+as occurs in hypokalemia ) Regardless of initial cause, persistence of metabolic alkalosis indicates that the kidneys have increased their HCO3 reabsorption, because HCO3 is normally freely filtered by the kidneys and hence excreted. Volume depletion and hypokalemia are the most common stimuli for increased HCO3 reabsorption, but any condition that elevates aldosterone or mineralocorticoids (which enhance sodium [Na] reabsorption and potassium [K] and hydrogen ion [H+] excretion) can elevate HCO3. Thus, hypokalemia is both a cause and a frequent consequence of metabolic alkalosis. The most common causes of metabolic alkalosis are Volume depletion (particularly when involving loss of gastric acid and chloride [Cl] due to recurrent vomiting or nasogastric suction) Among other causes (see Table: Causes of Metabolic Alkalosis ) are disorders that cause Continue reading >>
Acidosis Vs. Alkalosis
In this lesson, we're going to learn about acidosis and alkalosis. We'll take a look at the causes, signs, and symptoms that are associated with each condition. Balanced Blood We are constantly having to find balance in our lives. From balancing work and play time to saving and spending money, sleep and awake time. Well, ideally at least. We do this because we know that we function best when we're balanced. There are many similar balances that are going on inside of our bodies. An important balance that must be maintained to allow us to function properly is the balance between acids and bases in our bodies. When these are balanced, the acids pair up with the bases, and our blood is close to neutral. If too much acid is in the blood, then we experience acidosis. If too much base is in the blood, we experience alkalosis. Acidosis and alkalosis are caused by different conditions in our bodies, and they can cause different problems to occur. Acidosis Acidosis results from the build-up of acids in the blood or from the loss of base in the blood. Acids are put into our bloodstream through two systems in the body: the digestive system and the respiratory system. Acidosis that occurs from the digestive system is referred to as metabolic acidosis. In this instance, acids accumulate in the blood due to consumption of acidic foods or foods that are broken down into acids, excess acids being produced during metabolism, kidneys not properly removing acid from the bloodstream during filtration, or production of acid by the body due to other medical conditions, such as diabetes. The other possible way to develop acidosis is by the malfunctioning of the respiratory system, which we refer to as respiratory acidosis. This can happen if breathing is extremely slow or shallow, the lungs do Continue reading >>
Acidosis
When your body fluids contain too much acid, it’s known as acidosis. Acidosis occurs when your kidneys and lungs can’t keep your body’s pH in balance. Many of the body’s processes produce acid. Your lungs and kidneys can usually compensate for slight pH imbalances, but problems with these organs can lead to excess acid accumulating in your body. The acidity of your blood is measured by determining its pH. A lower pH means that your blood is more acidic, while a higher pH means that your blood is more basic. The pH of your blood should be around 7.4. According to the American Association for Clinical Chemistry (AACC), acidosis is characterized by a pH of 7.35 or lower. Alkalosis is characterized by a pH level of 7.45 or higher. While seemingly slight, these numerical differences can be serious. Acidosis can lead to numerous health issues, and it can even be life-threatening. There are two types of acidosis, each with various causes. The type of acidosis is categorized as either respiratory acidosis or metabolic acidosis, depending on the primary cause of your acidosis. Respiratory acidosis Respiratory acidosis occurs when too much CO2 builds up in the body. Normally, the lungs remove CO2 while you breathe. However, sometimes your body can’t get rid of enough CO2. This may happen due to: chronic airway conditions, like asthma injury to the chest obesity, which can make breathing difficult sedative misuse deformed chest structure Metabolic acidosis Metabolic acidosis starts in the kidneys instead of the lungs. It occurs when they can’t eliminate enough acid or when they get rid of too much base. There are three major forms of metabolic acidosis: Diabetic acidosis occurs in people with diabetes that’s poorly controlled. If your body lacks enough insulin, keton Continue reading >>
Types Of Disturbances
The different types of acid-base disturbances are differentiated based on: Origin: Respiratory or metabolic Primary or secondary (compensatory) Uncomplicated or mixed: A simple or uncomplicated disturbance is a single or primary acid-base disturbance with or without compensation. A mixed disturbance is more than one primary disturbance (not a primary with an expected compensatory response). Acid-base disturbances have profound effects on the body. Acidemia results in arrythmias, decreased cardiac output, depression, and bone demineralization. Alkalemia results in tetany and convulsions, weakness, polydipsia and polyuria. Thus, the body will immediately respond to changes in pH or H+, which must be kept within strict defined limits. As soon as there is a metabolic or respiratory acid-base disturbance, body buffers immediately soak up the proton (in acidosis) or release protons (alkalosis) to offset the changes in H+ (i.e. the body compensates for the changes in H+). This is very effective so minimal changes in pH occur if the body is keeping up or the acid-base abnormality is mild. However, once buffers are overwhelmed, the pH will change and kick in stronger responses. Remember that the goal of the body is to keep hydrogen (which dictates pH) within strict defined limits. The kidney and lungs are the main organs responsible for maintaining normal acid-base balance. The lungs compensate for a primary metabolic condition and will correct for a primary respiratory disturbance if the disease or condition causing the disturbance is resolved. The kidney is responsible for compensating for a primary respiratory disturbance or correcting for a primary metabolic disturbance. Thus, normal renal function is essential for the body to be able to adequately neutralize acid-base abnor Continue reading >>
What Is Metabolic Acidosis?
Metabolic acidosis happens when the chemical balance of acids and bases in your blood gets thrown off. Your body: Is making too much acid Isn't getting rid of enough acid Doesn't have enough base to offset a normal amount of acid When any of these happen, chemical reactions and processes in your body don't work right. Although severe episodes can be life-threatening, sometimes metabolic acidosis is a mild condition. You can treat it, but how depends on what's causing it. Causes of Metabolic Acidosis Different things can set up an acid-base imbalance in your blood. Ketoacidosis. When you have diabetes and don't get enough insulin and get dehydrated, your body burns fat instead of carbs as fuel, and that makes ketones. Lots of ketones in your blood turn it acidic. People who drink a lot of alcohol for a long time and don't eat enough also build up ketones. It can happen when you aren't eating at all, too. Lactic acidosis. The cells in your body make lactic acid when they don't have a lot of oxygen to use. This acid can build up, too. It might happen when you're exercising intensely. Big drops in blood pressure, heart failure, cardiac arrest, and an overwhelming infection can also cause it. Renal tubular acidosis. Healthy kidneys take acids out of your blood and get rid of them in your pee. Kidney diseases as well as some immune system and genetic disorders can damage kidneys so they leave too much acid in your blood. Hyperchloremic acidosis. Severe diarrhea, laxative abuse, and kidney problems can cause lower levels of bicarbonate, the base that helps neutralize acids in blood. Respiratory acidosis also results in blood that's too acidic. But it starts in a different way, when your body has too much carbon dioxide because of a problem with your lungs. Continue reading >>
Acidosis And Alkalosis | Harrison's Principles Of Internal Medicine, 19e | Accessmedicine | Mcgraw-hill Medical
Systemic arterial pH is maintained between 7.35 and 7.45 by extracellular and intracellular chemical buffering together with respiratory and renal regulatory mechanisms. The control of arterial CO2 tension (Paco2) by the central nervous system (CNS) and respiratory system and the control of plasma bicarbonate by the kidneys stabilize the arterial pH by excretion or retention of acid or alkali. The metabolic and respiratory components that regulate systemic pH are described by the Henderson-Hasselbalch equation: Under most circumstances, CO2 production and excretion are matched, and the usual steady-state Paco2 is maintained at 40 mmHg. Underexcretion of CO2 produces hypercapnia, and overexcretion causes hypocapnia. Nevertheless, production and excretion are again matched at a new steady-state Paco2. Therefore, the Paco2 is regulated primarily by neural respiratory factors and is not subject to regulation by the rate of CO2 production. Hypercapnia is usually the result of hypoventilation rather than of increased CO2 production. Increases or decreases in Paco2 represent derangements of neural respiratory control or are due to compensatory changes in response to a primary alteration in the plasma [HCO3]. DIAGNOSIS OF GENERAL TYPES OF DISTURBANCES The most common clinical disturbances are simple acid-base disorders; i.e., metabolic acidosis or alkalosis or respiratory acidosis or alkalosis. Primary respiratory disturbances (primary changes in Paco2) invoke compensatory metabolic responses (secondary changes in [HCO3]), and primary metabolic disturbances elicit predictable compensatory respiratory responses (secondary changes in Paco2). Physiologic compensation can be predicted from the relationships displayed in Table 66-1 . In general, with one exception, compensatory res Continue reading >>
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Alkalosis - Hormonal And Metabolic Disorders - Merck Manuals Consumer Version
By James L. Lewis, III, MD, Attending Physician, Brookwood Baptist Health and Saint Vincents Ascension Health, Birmingham Alkalosis is excessive blood alkalinity caused by an overabundance of bicarbonate in the blood or a loss of acid from the blood (metabolic alkalosis), or by a low level of carbon dioxide in the blood that results from rapid or deep breathing (respiratory alkalosis). People may have irritability, muscle twitching, muscle cramps, or even muscle spasms. Metabolic alkalosis is treated by replacing water and mineral salts such as sodium and potassium (electrolytes) and correcting the cause. Respiratory alkalosis is treated by correcting the cause. The acidity or alkalinity of any solution, including blood, is indicated on the pH scale . Acidity and alkalinity are expressed on the pH scale, which ranges from 0 (strongly acidic) to 14 (strongly basic or alkaline). A pH of 7.0, in the middle of this scale, is neutral. Blood is normally slightly basic, with a normal pH range of 7.35 to 7.45. Usually the body maintains the pH of blood close to 7.40. If too much bicarbonate in the blood, a loss of acid from the blood or a low level of carbon dioxide in the blood overwhelms the body's acid-base control systems , the blood will become alkalotic. Alkalosis is categorized depending on its primary cause as Metabolic alkalosis develops when the body loses too much acid or gains too much base. For example, stomach acid is lost during periods of prolonged vomiting or when stomach acids are suctioned with a stomach tube (as is sometimes done in hospitals). In rare cases, metabolic alkalosis develops in a person who has ingested too much base from substances such as baking soda (bicarbonate of soda). In addition, metabolic alkalosis can develop when excessive loss of fl Continue reading >>
Merck And The Merck Manuals
Acidosis is caused by an overproduction of acid in the blood or an excessive loss of bicarbonate from the blood (metabolic acidosis) or by a buildup of carbon dioxide in the blood that results from poor lung function or depressed breathing (respiratory acidosis). If an increase in acid overwhelms the body's acid-base control systems, the blood will become acidic. As blood pH drops (becomes more acidic), the parts of the brain that regulate breathing are stimulated to produce faster and deeper breathing (respiratory compensation). Breathing faster and deeper increases the amount of carbon dioxide exhaled. The kidneys also try to compensate by excreting more acid in the urine. However, both mechanisms can be overwhelmed if the body continues to produce too much acid, leading to severe acidosis and eventually heart problems and coma. The acidity or alkalinity of any solution, including blood, is indicated on the pH scale. Metabolic acidosis develops when the amount of acid in the body is increased through ingestion of a substance that is, or can be broken down (metabolized) to, an acid—such as wood alcohol (methanol), antifreeze (ethylene glycol), or large doses of aspirin (acetylsalicylic acid). Metabolic acidosis can also occur as a result of abnormal metabolism. The body produces excess acid in the advanced stages of shock and in poorly controlled type 1 diabetes mellitus (diabetic ketoacidosis). Even the production of normal amounts of acid may lead to acidosis when the kidneys are not functioning normally and are therefore not able to excrete sufficient amounts of acid in the urine. Major Causes of Metabolic Acidosis Diabetic ketoacidosis (buildup of ketoacids) Drugs and substances such as acetazolamide, alcohols, and aspirin Lactic acidosis (buildup of lactic acid Continue reading >>
