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Metabolic acidosis
Classification and external resources
Davenport diagram
ICD-10 E87.2
ICD-9 276.2
DiseasesDB 92
MedlinePlus 000335
eMedicine emerg/312  med/1458 ped/15

In medicine, metabolic acidosis is a process which if unchecked leads to acidemia (i. In Acid base physiology, the Davenport Diagram is a graphical tool developed by Horace Davenport, that allows a clinician or investigator to describe Blood The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify Diseases The International Statistical Classification of Diseases and Related Health Problems 10th Revision ( ICD -10) is a coding of diseases and signs symptoms abnormal findings E00-E35 - Endocrine diseases (E00-E07 Thyroid gland / Thyroid hormone ( Congenital iodine-deficiency syndrome ( The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify Diseases The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. The Diseases Database is a free Website that provides information about the relationships between medical conditions Symptoms, and Medications. MedlinePlus, with the MedlinePlus Medical Encyclopedia, is a website network containing Health information from the world's largest medical Library eMedicine is an online clinical medical knowledge base that was founded in 1996 by Scott Plantz and Richard Lavely two medical doctors Medicine is the art and science of healing It encompasses a range of Health care practices evolved to maintain and restore Human Health by the e. blood pH is low (less than 7. pH is the measure of the acidity or alkalinity of a Solution. 35) due to increased production of H+ by the body or the inability of the body to form bicarbonate (HCO3-) in the kidney. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 In Inorganic chemistry, bicarbonate ( IUPAC -recommended nomenclature hydrogencarbonate) is an intermediate form in the Deprotonation The kidneys are complicated organs that have numerous biological roles Its causes are diverse, and its consequences can be serious, including coma and death. In Medicine, a coma (from the Greek koma, meaning deep sleep is a profound state of Unconsciousness. Death is the termination of the biological functions that define living Organisms It refers both to a specific Together with respiratory acidosis, it is one of the two general causes of acidemia. Respiratory acidosis is Acidosis (abnormally increased acidity of the blood due to decreased ventilation of the pulmonary Alveoli, leading to

Contents

Signs and symptoms

Symptoms are aspecific, and diagnosis can be difficult unless the patient presents with clear indications for arterial blood gas sampling. An arterial blood gas ( ABG) is a Blood test that is performed specifically on Blood from an Artery. Symptoms may include chest pain, palpitations, headache, altered mental status, decreased visual acuity, nausea, vomiting, abdominal pain, altered appetite (either loss of or increased) and weight loss (longer term), muscle weakness and bone pains. In Medicine, chest pain is a Symptom of a number of serious conditions and is generally considered a Medical emergency. A palpitation (medical term ectopic heart beat) is an abnormal awareness of the beating of the Heart, whether it is too slow too fast irregular A headache ( cephalalgia in medical terminology is a condition of pain in the Head; sometimes Neck or upper back pain may also be interpreted Nausea ( Latin: Nausea, Greek:, " Sea-sickness " also called wamble) is the sensation of unease and discomfort Vomiting (also called throwing up, emesis) is the forceful expulsion of the contents of one's Stomach through the Mouth and sometimes the Abdominal pain can be one of the Symptoms associated with transient disorders or serious disease Weight loss, in the context of Medicine or Health or Physical fitness, is a reduction of the total Body weight, due to a mean loss of fluid Muscle weakness (or "lack of strength" is a direct term for the inability to exert force with one's Muscles to the degree that would be expected given the individual's The term ' Bone pain' (or Ostealgia, or Osteodynia) generally is used to refer to Pain felt within a bone Those in metabolic acidosis may exhibit deep, rapid breathing called Kussmaul respirations which is classically associated with diabetic ketoacidosis. Kussmaul breathing is the very deep and labored Breathing with normal or reduced frequency found among people with severe Acidosis; it is a form of Hyperventilation Ketoacidosis is a type of metabolic Acidosis which is caused by high concentrations of Ketone bodies, formed by the Deamination of Amino acids Rapid deep breaths increase the amount of carbon dioxide exhaled, thus lowering the serum carbon dioxide levels, resulting in some degree of compensation. Over compensation via respiratory alkalosis to form an alkalemia does not occur.

Extreme acidemia leads to neurological and cardiac complications:

Physical examination occasionally reveals signs of disease, but is otherwise normal. Physical examination or clinical examination is the process by which a Health care provider investigates the body of a Patient for signs Cranial nerve abnormalities are reported in ethylene glycol poisoning, and retinal edema can be a sign of methanol (methyl alcohol) intoxication. Cranial nerves are Nerves that emerge directly from the Brain stem in contrast to Spinal nerves which emerge from segments of the Spinal cord. Ethylene glycol ( monoethylene glycol ( MEG) 12-ethanediol, IUPAC name: ethane-12-diol) is an Alcohol with two -OH The vertebrate retina is a light sensitive part inside the inner layer of the Eye. Oedema (or Edema in American English formerly known as dropsy or hydropsy, is the increase of Interstitial fluid in any organ &mdash swelling Methanol, also known as methyl alcohol, carbinol, wood alcohol, wood naphtha or wood spirits, is a Chemical compound Longstanding chronic metabolic acidosis leads to osteoporosis and can cause fractures. Osteoporosis is a Disease of Bone that leads to an increased risk of fracture. A fracture is the (local separation of an object or material into two or more pieces under the action of stress.

Diagnosis

Arterial blood gas sampling is essential for the diagnosis. An arterial blood gas ( ABG) is a Blood test that is performed specifically on Blood from an Artery. The pH is low (under 7. 35) and the bicarbonate levels are decreased (<24 mmol/l). Due to respiratory compensation (hyperventilation), carbon dioxide is decreased and conversely oxygen is increased. An ECG can be useful to anticipate cardiac complications.

Other tests that are relevant in this context are electrolytes (including chloride), glucose, renal function and a full blood count. An electrolyte is any substance containing free Ions that behaves as an electrically conductive medium The chloride Ion is formed when the element Chlorine picks up one Electron to form an Anion (negatively-charged ion Cl&minus Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. Renal function, in Nephrology, is an indication of the state of the Kidney and its role in Renal physiology. A complete blood count ( CBC) also known as full blood count ( FBC) or full blood exam ( FBE) or blood panel, is Urinalysis can reveal acidity (salicylate poisoning) or alkalinity (renal tubular acidosis type I). Salicylic acid (from the Latin word for the willow tree Salix, from whose bark it can be obtained is a Beta hydroxy acid (BHA with the formula In addition, it can show ketones in ketoacidosis.

To distinguish between the main types of metabolic acidosis, a clinical tool called the anion gap is considered very useful. The anion gap is used to aid in the Differential diagnosis of Metabolic acidosis. It is calculated by subtracting the chloride and bicarbonate levels from the sodium.

Anion gap = ( [Na+] ) - ( [Cl-]+[HCO3-] )

As sodium is the main extracellular cation, and chloride and bicarbonate are the main anions, the result should reflect the remaining anions. Normally, this concentration is about 8-16 mmol/l (12±4). An elevated anion gap (i. e. > 16 mmol/l) can indicate particular types of metabolic acidosis, particularly certain poisons, lactate acidosis and ketoacidosis.

As the differential diagnosis is narrowed down, certain other tests may be necessary, including toxicological screening and imaging of the kidneys. A differential diagnosis (sometimes abbreviated DDx, ddx

Causes

The causes are best grouped by their influence on the anion gap:

Increased anion gap

Causes include:

The mnemomic MUDPILES is commonly used to remember the causes of Increased anion gap metabolic acidosis. The anion gap is used to aid in the Differential diagnosis of Metabolic acidosis. Lactic acidosis is a condition caused by the buildup of Lactic acid in the body Ketoacidosis is a type of metabolic Acidosis which is caused by high concentrations of Ketone bodies, formed by the Deamination of Amino acids Chronic kidney disease (CKD also known as chronic renal disease, is a progressive loss of renal function over a period of months or years A phosphate, an Inorganic chemical, is a salt of Phosphoric acid. Uric acid (or urate) is an Organic compound of Carbon, Nitrogen, Oxygen and Hydrogen with the formula C5H4N4O3 An organic acid is an Organic compound with Acidic properties Salicylic acid (from the Latin word for the willow tree Salix, from whose bark it can be obtained is a Beta hydroxy acid (BHA with the formula Methanol, also known as methyl alcohol, carbinol, wood alcohol, wood naphtha or wood spirits, is a Chemical compound Formaldehyde is a Chemical compound with the formula H2CO It is the simplest Aldehyde —an organic compound containing a terminal Carbonyl Ethylene glycol ( monoethylene glycol ( MEG) 12-ethanediol, IUPAC name: ethane-12-diol) is an Alcohol with two -OH Paraldehyde is the cyclic form of three Acetaldehyde molecules (a trimer Isoniazid (also called isonicotinyl hydrazine or INH) is a first-line antituberculous medication used in the prevention and treatment of Tuberculosis Toluene, also known as methylbenzene or phenylmethane, is a clear water -insoluble liquid with the typical smell of Paint thinners redolent of Metformin ( INN; trade names Glucophage, Riomet, Fortamet, Glumetza, Obimet, Dianben, Diabex, Rhabdomyolysis is the rapid breakdown ( Lysis) of Skeletal muscle tissue ( rhabdomyo) due to injury to muscle tissue [1][2]

Note: Ethanol is sometimes included in this mnemonic as well, although the acidosis caused by ethanol is actually primarily due to the increased production of lactic acid found in such intoxication.

Normal anion gap

Causes include:[3]

It bears noting that the anion gap can be spuriously normal in sampling errors of the sodium level, e. In Medicine, diarrhea, also spelled diarrhoea (see spelling differences) is frequent loose or liquid Bowel movements Acute diarrhea A pancreatic fistula is an abnormal communication between the Pancreas and other organs due to leakage of pancreatic secretions from damaged pancreatic ducts Renal tubular acidosis ( RTA) is a medical condition that involves an accumulation of acid in the body due to a failure of the kidneys to appropriately acidify Ammonium chloride ( N[[Hydrogen H]]4 Cl) (also Sal Ammoniac, salmiac, nushadir salt, zalmiak, sal armagnac Acetazolamide, sold under the trade name Diamox, is a Carbonic anhydrase inhibitor that is used to treat Glaucoma, Epileptic seizures Benign The bile acid sequestrants are a group of medications used for binding certain components of Bile in the gastrointestinal tract. Isopropyl alcohol (also isopropanol, iso, isopro, Rubbing alcohol, or the abbreviation IPA) is a common name for Renal failure or kidney g. in extreme hypertriglyceridemia. In Medicine, hypertriglyceridemia (or "Hypertriglyceridaemia" denotes high ( hyper-) blood levels ( -emia) of Triglycerides the most The anion gap can be increased due to relatively low levels of cations other than sodium and potassium (e. g. calcium or magnesium).

Pathophysiology

Compensatory mechanisms

Metabolic acidosis is either due to increased generation of acid or an inability to generate sufficient bicarbonate. The body regulates the acidity of the blood by four buffering mechanisms.

Buffer

The decreased bicarbonate that distinguishes metabolic acidosis is therefore due to two separate processes: the buffer (from water and carbon dioxide) and additional renal generation. Respiratory compensation is a mechanism by which plasma pH can be altered by varying the Respiratory rate. Renal compensation is a mechanism by which the Kidneys can regulate the plasma PH. The buffer reactions are:

H+ + HCO3- <--> H2CO3 <--> CO2 + H2O

The Henderson-Hasselbalch equation mathematically describes the relationship between blood pH and the components of the bicarbonate buffering system:

pH=pKa + log [HCO3-]/[CO2]
Using Henry's Law, we can say that [CO2]=0. 03xPaCO2
(PaCO2 is the pressure of CO2 in arterial blood)
Adding the other normal values, we get
pH = 6. 1 + log (24/0. 03x40)
= 6. 1 + 1. 3
= 7. 4

Treatment

A pH under 7. 1 is an emergency, due to the risk of cardiac arrhythmias, and may warrant treatment with intravenous bicarbonate. Dysrhythmia redirects here For the American band see Dysrhythmia (band. Bicarbonate is given at 50-100 mmol at a time under scrupulous monitoring of the arterial blood gas readings. This intervention however, is not effective in case of lactic acidosis. Lactic acidosis is a condition caused by the buildup of Lactic acid in the body

If the acidosis is particularly severe and/or there may be intoxication, consultation with the nephrology team is considered useful, as dialysis may clear both the intoxication and the acidosis. Nephrology (from Greek nephros, " Kidney " and λόγος Logos, "speech" lit In Medicine, dialysis (from Greek "dialusis" meaning dissolution "dia" meaning through and "lusis" meaning loosening is primarily

References

  1. ^ Mnemonic at medicalmnemonics.com 1203 3255
  2. ^ Anion Gap: Acid Base Tutorial, University of Connecticut Health Center
  3. ^ Mnemonic at medicalmnemonics.com 2001
A mnemonic device (nəˈmɒnɪk is a Memory aid Commonly met mnemonics are often verbal something such as a very short poem or a special word used to help a person remember A mnemonic device (nəˈmɒnɪk is a Memory aid Commonly met mnemonics are often verbal something such as a very short poem or a special word used to help a person remember
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