Metabolic Acidosis
Metabolic acidosis is a condition that occurs when the body produces excessive quantities of acid or when the kidneys are not removing enough acid from the body. If unchecked, metabolic acidosis leads to acidemia, i.e., blood pH is low (less than 7.35) due to increased production of hydrogen ions by the body or the inability of the body to form bicarbonate (HCO3−) in the kidney. Its causes are diverse, and its consequences can be serious, including coma and death. Together with respiratory acidosis, it is one of the two general causes of acidemia. Terminology : Acidosis refers to a process that causes a low pH in blood and tissues. Acidemia refers specifically to a low pH in the blood. In most cases, acidosis occurs first for reasons explained below. Free hydrogen ions then diffuse into the blood, lowering the pH. Arterial blood gas analysis detects acidemia (pH lower than 7.35). When acidemia is present, acidosis is presumed. Signs and symptoms[edit] Symptoms are not specific, and diagnosis can be difficult unless the patient presents with clear indications for arterial blood gas sampling. Symptoms may include chest pain, palpitations, headache, altered mental status such as severe anxiety due to hypoxia, decreased visual acuity, nausea, vomiting, abdominal pain, altered appetite and weight gain, muscle weakness, bone pain, and joint pain. Those in metabolic acidosis may exhibit deep, rapid breathing called Kussmaul respirations which is classically associated with diabetic ketoacidosis. Rapid deep breaths increase the amount of carbon dioxide exhaled, thus lowering the serum carbon dioxide levels, resulting in some degree of compensation. Overcompensation via respiratory alkalosis to form an alkalemia does not occur. Extreme acidemia leads to neurological and cardia Continue reading >>
Acid/base Disorders: Metabolic Acidosis
Are there clinical practice guidelines to inform decision-making? Does this patient have metabolic acidosis? Metabolic acidosis is generally defined by the presence of a low serum bicarbonate concentration (normal range 22-28 mEq/L), although occasionally states can exist where the serum bicarbonate is normal with an elevated anion gap (e.g., patients with a lactic acidosis who have received a bicarbonate infusion or patients on hemodialysis). In general, a metabolic acidosis is associated with a low urine pH but depending on the presence or absence of a respiratory alkalosis, this may also be normal or elevated. Thus, a patient can have an acidosis but not be acidemic. Metabolic acidoses occur when there is excess acid in the plasma. In the basal state, the body generates about 12,000 to 13,000 mmol of carbon dioxide (CO2), and 1-1.5 mmol per kilogram body weight of nonvolatile acid. The body has a large buffering capacity, with CO2-HCO3 as the major buffer system. The two major routes of acid excretion are the lungs (for CO2) and the kidneys (for nonvolatile acids) A metabolic acidosis can be caused by three major mechanisms: 1) increased acid production; 2) bicarbonate loss; and 3) decreased renal acid excretion Increased acid production leads to anion-gap (AG) metabolic acidosis, and involves a variety of different clinical processes, see An anion gap acidosis may also result for ingestion of an acid load. Both bicarbonate loss and decreased renal acid excretion lead to normal-anion gap (NG) metabolic acidosis. When there is HCO3 loss, chloride is retained to maintain electrical neutrality. The different clinical processes are summarized in Toxic ingestions are common causes of AG metabolic acidosis. The commonest causes are methanol and ethylene glycol intoxicatio Continue reading >>
Treatment Of Acute Non-anion Gap Metabolic Acidosis
Treatment of acute non-anion gap metabolic acidosis Medical and Research Services VHAGLA Healthcare System, Division of Nephrology, VHAGLA Healthcare System Correspondence to: Jeffrey A. Kraut; E-mail: [email protected] Search for other works by this author on: Clinical Kidney Journal, Volume 8, Issue 1, 1 February 2015, Pages 9399, Jeffrey A. Kraut, Ira Kurtz; Treatment of acute non-anion gap metabolic acidosis, Clinical Kidney Journal, Volume 8, Issue 1, 1 February 2015, Pages 9399, Acute non-anion gap metabolic acidosis, also termed hyperchloremic acidosis, is frequently detected in seriously ill patients. The most common mechanisms leading to this acidbase disorder include loss of large quantities of base secondary to diarrhea and administration of large quantities of chloride-containing solutions in the treatment of hypovolemia and various shock states. The resultant acidic milieu can cause cellular dysfunction and contribute to poor clinical outcomes. The associated change in the chloride concentration in the distal tubule lumen might also play a role in reducing the glomerular filtration rate. Administration of base is often recommended for the treatment of acute non-anion gap acidosis. Importantly, the blood pH and/or serum bicarbonate concentration to guide the initiation of treatment has not been established for this type of metabolic acidosis; and most clinicians use guidelines derived from studies of high anion gap metabolic acidosis. Therapeutic complications resulting from base administration such as volume overload, exacerbation of hypertension and reduction in ionized calcium are likely to be as common as with high anion gap metabolic acidosis. On the other hand, exacerbation of intracellular acidosis due to the excessive generation of carbon dioxide migh Continue reading >>
Pathogenesis Of Metabolic Acidosis With Hypoxia
Pathogenesis of Metabolic Acidosis with Hypoxia Part of the Clinical Physiology Series book series (CLINPHY) Metabolic acidosis is broadly defined as a condition characterized by an arterial pH below 7.35 in the absence of hypercapnia. There are several varieties of metabolic acidosis, and one method of classification is on the basis of the anion gap. The anion gap (AG) is defined as the difference between the blood concentration of sodium (Na) minus those of chloride (Cl) and bicarbonate (HCO3) (39,69). Thus, metabolic acidosis can be classified according to whether the AG is normal, low, or elevated. Increased AG metabolic acidosis includes those disorders of acidbase metabolism where there is acidosis because of the presence of increased quantities of organic acid(s). Such organic acids may be either endogenous (keto acids, lactic acid) or exogenous (salicylate, paraldehyde). Those forms of metabolic acidosis with normal to low AG are primarily the renal tubular acidoses, which are not discussed in this chapter. In equation form, the AG can be defined as in equation 1, below. Metabolic AcidosisLactic AcidosisLactate ProductionTissue HypoxiaLactic Acid Production These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves. This is a preview of subscription content, log in to check access Unable to display preview. Download preview PDF. Adrogue, H. J., M. N. Rashad, A. B. Gorin, J. Yacoub, and N. E. Madias: Assessing acidbase status in circulatory failure. Differences between arterial and central venous blood. N. Engl. J. Med. 320: 13121316, 1989. PubMed CrossRef Google Scholar Alella, A., F. L. Williams, C. B. Williams, and L. N. Katz: Interrelation between cardiac oxygen Continue reading >>
Metabolic Acidosis
Metabolic acidosis occurs when the body produces too much acid. It can also occur when the kidneys are not removing enough acid from the body. There are several types of metabolic acidosis. Diabetic acidosis develops when acidic substances, known as ketone bodies, build up in the body. This most often occurs with uncontrolled type 1 diabetes. It is also called diabetic ketoacidosis and DKA. Hyperchloremic acidosis results from excessive loss of sodium bicarbonate from the body. This can occur with severe diarrhea. Lactic acidosis results from a buildup of lactic acid. It can be caused by: Alcohol Cancer Exercising intensely Liver failure Medicines, such as salicylates Other causes of metabolic acidosis include: Kidney disease (distal renal tubular acidosis and proximal renal tubular acidosis) Poisoning by aspirin, ethylene glycol (found in antifreeze), or methanol Continue reading >>
5.1 - Metabolic Acidosis : Definition
Acid-Base Physiology A metabolic acidosis is an abnormal primary process or condition leading to an increase in fixed acids in the blood. This causes the arterial plasma bicarbonate to fall to a level lower than expected. The fall in plasma bicarbonate is due to titration of HCO3- by H+. Secondary or compensatory processes which cause a fall in plasma bicarbonate should not be confused with primary processes. A fall in bicarbonate occurring in response to a chronic respiratory alkalosis should be referred to as a compensatory response and never as a �secondary metabolic acidosis�. This distinction between a primary process and a secondary one has been discussed previously in section 3.1.2 when discussing terminology of acid-base disorders. It is of course possible for a patient to have a mixed acid-base disorder with both a metabolic acidosis and a respiratory alkalosis. An example would be an adult presenting following a salicylate overdose. In this situation, direct stimulation of the respiratory centre occurs resulting in a respiratory alkalosis as well as the salicylate-related metabolic acidosis. 'Acid-base pHysiology' by Kerry Brandis -from Acid-Base Physiology 5.2.1 Classification by Patho-physiological Mechanism A decrease in plasma bicarbonate can be caused by two mechanisms: A gain of strong acid A loss of base All causes of a metabolic acidosis must work by these mechanisms. The gain of strong acid may be endogenous (eg ketoacids from lipid metabolism) or exogenous (NH4Cl infusion). Bicarbonate loss may occur via the bowel (diarrhoea, small bowel fistulas) or via the kidneys (carbonic anhydrase inhibitors, renal tubular acidosis). An alternative to the above, is to classify the causes of metabolic acidosis into two groups depending on whether the anion ga 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 >>
Patterns Of Metabolic Acidosis In Patients With Chronic Renal Failure: Impact Of Hemodialysis.
Patterns of metabolic acidosis in patients with chronic renal failure: impact of hemodialysis. Northwestern University Medical School, Chicago. The type of metabolic acidosis in patients with chronic renal failure was studied prospectively over a three-month period in 32 stable patients on chronic hemodialysis using acetate. All patients had pre-dialysis metabolic acidosis (mean TCO2 = 16.6 +/- 0.4 mEq/l, range 10 to 23 mEq/l). The patterns of metabolic acidosis were defined using the ratio: delta AG/delta TCO2 where delta AG is the increment in plasma anion gap above normal and delta TCO2 the decrement in plasma bicarbonate below normal. The group as a whole showed a mixed hyperchloremic and high anion gap pattern with a mean delta AG/delta TCO2 ratio of 53.3 +/- 7.1%. The individual distribution of patterns ranged from a pure hyperchloremic acidosis (24%) to a pure high anion gap acidosis (30%) with the mixed pattern being the most frequent (46%). An inverse correlation between the TCO2 change (y) during the dialysis procedure and the TCO2 (x) prevailing at the start of dialysis was found by linear regression analysis: y = -0.51x + 11, r = -0.54, p less than 0.01. Thus, before acetate conversion to bicarbonate was fully completed, patients gained bicarbonate during dialysis if TCO2 was less than 21 mEq/l and lost it when the pre-dialysis TCO2 was above this level. On average, the delta AG was reduced to a greater extent than the delta TCO2 so that the delta AG/delta TCO2 ratio fell significantly (from 53 +/- 7.1 to 11 +/- 8.8%, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS). 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 >>
Metabolic Acidosis
Patient professional reference Professional Reference articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use. You may find one of our health articles more useful. See also separate Lactic Acidosis and Arterial Blood Gases - Indications and Interpretations articles. Description Metabolic acidosis is defined as an arterial blood pH <7.35 with plasma bicarbonate <22 mmol/L. Respiratory compensation occurs normally immediately, unless there is respiratory pathology. Pure metabolic acidosis is a term used to describe when there is not another primary acid-base derangement - ie there is not a mixed acid-base disorder. Compensation may be partial (very early in time course, limited by other acid-base derangements, or the acidosis exceeds the maximum compensation possible) or full. The Winter formula can be helpful here - the formula allows calculation of the expected compensating pCO2: If the measured pCO2 is >expected pCO2 then additional respiratory acidosis may also be present. It is important to remember that metabolic acidosis is not a diagnosis; rather, it is a metabolic derangement that indicates underlying disease(s) as a cause. Determination of the underlying cause is the key to correcting the acidosis and administering appropriate therapy[1]. Epidemiology It is relatively common, particularly among acutely unwell/critical care patients. There are no reliable figures for its overall incidence or prevalence in the population at large. Causes of metabolic acidosis There are many causes. They can be classified according to their pathophysiological origin, as below. The table is not exhaustive but lists those that are most common or clinically important to detect. Increased acid Continue reading >>
Metabolic Acidosis: Practice Essentials, Background, Etiology
Metabolic acidosis is a clinical disturbance characterized by an increase in plasma acidity. Metabolic acidosis should be considered a sign of an underlying disease process. Identification of this underlying condition is essential to initiate appropriate therapy. (See Etiology, DDx, Workup, and Treatment.) Understanding the regulation of acid-base balance requires appreciation of the fundamental definitions and principles underlying this complex physiologic process. Go to Pediatric Metabolic Acidosis and Emergent Management of Metabolic Acidosis for complete information on those topics. An acid is a substance that can donate hydrogen ions (H+). A base is a substance that can accept H+ ions. The ion exchange occurs regardless of the substance's charge. Strong acids are those that are completely ionized in body fluids, and weak acids are those that are incompletely ionized in body fluids. Hydrochloric acid (HCl) is considered a strong acid because it is present only in a completely ionized form in the body, whereas carbonic acid (H2 CO3) is a weak acid because it is ionized incompletely, and, at equilibrium, all three reactants are present in body fluids. See the reactions below. The law of mass action states that the velocity of a reaction is proportional to the product of the reactant concentrations. On the basis of this law, the addition of H+ or bicarbonate (HCO3-) drives the reaction shown below to the left. In body fluids, the concentration of hydrogen ions ([H+]) is maintained within very narrow limits, with the normal physiologic concentration being 40 nEq/L. The concentration of HCO3- (24 mEq/L) is 600,000 times that of [H+]. The tight regulation of [H+] at this low concentration is crucial for normal cellular activities because H+ at higher concentrations can b Continue reading >>
Metabolic Acidosis
Metabolic Acidosis Definition Metabolic acidosis is a pH imbalance in which the body has accumulated too much acid and does not have enough bicarbonate to effectively neutralize the effects of the acid. Description Metabolic acidosis, as a disruption of the body's acid/base balance, can be a mild symptom brought on by a lack of insulin, a starvation diet, or a gastrointestinal disorder like vomiting and diarrhea. Metabolic acidosis can indicate a more serious problem with a major organ like the liver, heart, or kidneys. It can also be one of the first signs of drug overdose or poisoning. Causes and symptoms Metabolic acidosis occurs when the body has more acid than base in it. Chemists use the term "pH" to describe how acidic or basic a substance is. Based on a scale of 14, a pH of 7.0 is neutral. A pH below 7.0 is an acid; the lower the number, the stronger the acid. A pH above 7.0 is a base; the higher the number, the stronger the base. Blood pH is slightly basic (alkaline), with a normal range of 7.36-7.44. Acid is a natural by-product of the breakdown of fats and other processes in the body; however, in some conditions, the body does not have enough bicarbonate, an acid neutralizer, to balance the acids produced. This can occur when the body uses fats for energy instead of carbohydrates. Conditions where metabolic acidosis can occur include chronic alcoholism, malnutrition, and diabetic ketoacidosis. Consuming a diet low in carbohydrates and high in fats can also produce metabolic acidosis. The disorder may also be a symptom of another condition like kidney failure, liver failure, or severe diarrhea. The build up of lactic acid in the blood due to such conditions as heart failure, shock, or cancer, induces metabolic acidosis. Some poisonings and overdoses (aspirin, Continue reading >>
Acute Metabolic Acidosis: Characterization And Diagnosis Of The Disorder And The Plasma Potassium Response
Acute Metabolic Acidosis: Characterization and Diagnosis of the Disorder and the Plasma Potassium Response *From the Medizinische Universitaetsklinik Kantonsspital Bruderholz, Bruderholz, Switzerland; and †Institute of Physiology, Departement of Veterinary Medicine, University of Zurich, Switzerland; and ‡Genentech Inc., South San Francisco, California. Correspondence to Dr. Reto Krapf, Medizinische Universitaetsklinik, Kantonsspital Bruderholz, CH 4101 Bruderholz/Basel, Switzerland. Phone: 0041-61-436-21-81; E-mail: reto.krapf{at}ksbh.ch Received for publication December 30, 2003. Accepted for publication February 25, 2004. ABSTRACT. Despite the high incidence of acute metabolic acidosis, there are no reliable human data to enable physicians to accurately diagnose this disorder. In addition, there is uncertainty about the direction and magnitude of plasma potassium changes in acute metabolic acidosis. The systemic and renal acid-base, electrolyte, and endocrine response to acute acid loads (imposed by three timed NH4Cl infusions into the duodenum, 0.9 mmol of NH4Cl per kg of body weight over 30 min each) was characterized in six healthy male subjects in whom a metabolic steady-state had been established. Arterialized blood CO2 tension decreased by 0.85 mmHg per mmol/L decrease in plasma bicarbonate concentration and blood hydrogen ion concentration increased by 0.45 nmol/L per mmol/L decrease in plasma bicarbonate concentration. Plasma potassium did not change significantly (+0.02 ± 0.02 mmol/L per mmol decrease in plasma bicarbonate concentration). Plasma insulin increased and plasma glucagon levels decreased in acute metabolic acidosis, while catecholamines and aldosterone were not affected significantly. These data provide the first diagnostic criteria for the Continue reading >>
What Is Metabolic Acidosis?
What keeps your blood from becoming too acidic or basic? How does the body control this? Read this lesson to learn about what happens when this balance is overthrown and the blood becomes too acidic, in a scenario called metabolic acidosis. Your body needs to stay approximately around a given equilibrium to function normally. There is a little bit of wiggle room, but not much, and when things go awry, the body begins to suffer. Our blood is literally our life source - it carries oxygen to the body and helps remove waste materials so we can function properly. Under normal conditions, our blood pH is around 7.4, but sometimes this balance is thrown off and the blood becomes more acidic. This condition is called metabolic acidosis. In this scenario, the body is either producing too much acid, not getting rid of enough acid, or fails to make enough base to neutralize the acid. (A neutral pH value is 7.0; higher numbers are more basic or alkaline and lower numbers are more acidic.) Causes of Metabolic Acidosis Metabolic acidosis sounds like something out of a horror movie - acidic blood?! What would cause the body to do this? Well, there are a few known causes, some of which we'll discuss below. Ketoacidosis: The body creates ketones when it burns fats instead of carbohydrates for energy, and ketones make the blood acidic. When you are fasting, causing your body to switch to fats for fuel, or when you drink too much alcohol, you risk the build up of ketones in the blood. Diabetics are also at risk of this condition when the body fails to produce enough insulin. Lactic acidosis: Notice an acidosis trend here? The body's cells create lactic acid when they are deprived of oxygen. You may experience bouts of lactic acidosis during intense exercise or due to heart conditions. Ren Continue reading >>
Defining Metabolic Acidosis
Metabolic acidosis is common in ill and injured animals. In humans, metabolic acidosis has diagnostic, therapeutic, and prognostic value; this may also be true in animals. Metabolic acidosis occurs when the accumulation of nonvolatile acids or loss of bicarbonate exceeds the body’s buffering capability. Acid base parameters, electrolytes, and lactate concentrations were reviewed from dogs and cats admitted to a veterinary medical teaching hospital over 13 months. Values were measured from heparinized blood samples immediately after collection on a point-of-care machine. Metabolic acidosis was defined as a standardized base excess of <-4 mmol/L (dogs) and <-5mmol/L (cats). Of the 1805 dogs and cats having ≥1 blood sample analyzed, 887 (49%) had metabolic acidosis (753 dogs, 134 cats). Metabolic acidosis was associated with various underlying diseases; neoplasia was most common in dogs and renal disease most common in cats. The most common acid–base abnormality was primary metabolic acidosis. Mixed acid–base disorders were more common in both dogs and cats than were simple disorders; primary respiratory alkalosis was the least common abnormality. Hyperchloremic metabolic acidosis was more common than high anion gap (AG) metabolic acidosis. Twenty-five percent of dogs and 34% of cats with metabolic acidosis could not be classified as having either hyperchloremia or high AG. Routine categorization of metabolic acidosis based on high AG or hyperchloremia alone may be misleading. Commentary AG, bicarbonate/TCO2, and chloride levels are all means by which acid–base status can be evaluated in practice. Even without a blood gas analyzer, a potential metabolic imbalance can be gleaned via serum biochemistry panel and evaluation. Metabolic acidosis results from either a Continue reading >>
