The following signs and symptoms are commonly seen in patients having lactic acidosis:

• Nausea
• Weakness
• Tachypnea
• Hypotension
• Confusion
• Oliguria
• Kussmaul’s breathing
• Lethargy

• Congestive Heart Failure

  He carried a diagnosis of severe congestive heart failure, with frequent episodes of decompensation, and was in decompensated congestive heart failure on admission. [cjasn.asnjournals.org]

  Nonetheless, diabetes experts recommend that metformin not be used in people with congestive heart failure, kidney disease, or liver disease. [diabetesselfmanagement.com]

  […] attack, severe congestive heart failure, kidney failure, or uncontrolled diabetes. [labtestsonline.org]

  Some of these conditions could include: Sepsis Heart attack Congestive heart failure Severe lung disease or respiratory failure Fluid build-up in your lungs Very low red blood cell count (severe anemia ) A higher-than-normal lactic acid level in your [webmd.com]

  Some common causes include: Heart disease Conditions such as cardiac arres t and congestive heart failure may reduce the flow of blood and oxygen throughout the body. This can increase lactic acid levels. [healthline.com]

• Epilepsy

  We reviewed epilepsy characteristics and clinical outcome exclusively in a pediatric population. [ncbi.nlm.nih.gov]

  Many neurological conditions such as epilepsy, anxiety, irritability, schizophrenia, depression, tremors, Parkinson-ism and extra pyramidal syndromes show remarkable improvement with correction of the acid-base imbalance. [platinumenergysystems.ca]

  MELAS) Stroke‐like episodes before age 40 years Seizures and/or dementia Ragged‐red fibres and/or lactic acidosis Diabetes mellitus Cardiomyopathy (hypertrophic leading to dilated) Bilateral deafness Pigmentary retinopathy Cerebellar ataxia Myoclonic epilepsy [dx.doi.org]

• Unconsciousness

  Left untreated, lactic acidosis can result in the following complications: Irregular heartbeats; Shock, and; Unconsciousness, coma and death. Prognosis The prognosis for lactic acidosis depends on its cause. [healthand.com]

  Low blood sugar must be treated before it causes you to pass out (unconsciousness). People feel different symptoms of low blood sugar. It is important that you learn which symptoms you usually have so you can treat it quickly. [mayoclinic.org]

  As the acid level goes up these symptoms progress to stupor, unconsciousness, coma, and death. The breath may have a fruity odor owing to the presence of acetone, and the patient may experience vomiting and diarrhea. [medical-dictionary.thefreedictionary.com]

• Tachypnea

  During his physical examination, the patient appeared dehydrated and had tachypnea and a reduced level of consciousness. His laboratory tests showed that he had acute kidney injury and severe lactic acidosis. [ncbi.nlm.nih.gov]

  Symptoms: Patients with diagnosed lactic acidosis presents with nausea, tachypnea, hypotension, lethargy, oliguria, weakness, and confusion. [symptoma.com]

  Tachypnea in physiological response to metabolic acidosis can be an early sign. Gastrointestinal side effects are a common side effect with therapeutic metformin use in the absence of lactic acidosis. [calpoison.org]

  The development of lactic acidosis depends on the magnitude of hyperlactatemia, the buffering capacity of the body, and the coexistence of other conditions that produce tachypnea and alkalosis (eg, liver disease, sepsis). [emedicine.medscape.com]

• Kussmaul Respiration

  Kussmaul respirations, a deep breathing pattern, may be seen as the body attempts to compensate for the metabolic acidosis.[7][8][9][10] Evaluation In any patient suspected of having a metabolic acidosis, serum electrolytes should be drawn, and arterial [ncbi.nlm.nih.gov]

• Hyperpnea

  Frank acidosis with hyperpnea and increased anion gaps became evident after lactate levels exceeded 12 mmol per liter. [doi.org]

• Nausea

  Our patient presented with exercise intolerance, rapid fatigue, and nausea since early childhood. Mild physical workload provoked the occurrence of nausea and vomiting repeatedly. [ncbi.nlm.nih.gov]

  […] cause lactic acidosis: Certain inhalers used to treat asthma or COPD Epinephrine An antibiotic called linezolid Metformin, used to treat diabetes (most often when overdosed) One type of medicine used to treat HIV infection Propofol Symptoms may include: Nausea [nlm.nih.gov]

• Vomiting

  CASE REPORT A 50-year-old Chinese female was diagnosed with endocarditis and thus received LZD therapy for 25 days, then complained about 6 days' abdominal pain and vomiting before being admitted to the Emergency Department. [ncbi.nlm.nih.gov]

• Abdominal Pain

  Although nausea and abdominal pain are the more common gastrointestinal features, rare gastrointestinal spectrums have been reported that can mimic abdominal emergencies. [ncbi.nlm.nih.gov]

• Flatulence

  Other side effects include diarrhoea, nausea, upset stomach and flatulence. Taking Metformin with meals can help to diminish these side effects. Some diabetics experience an unpleasant metallic taste when taking Metformin. [diabetes.co.uk]

  Diarrhea, nausea, vomiting, abdominal bloating, abdominal cramping or pain, flatulence, and anorexia are the most common gastrointestinal symptoms associated with metformin therapy. [cochranelibrary.com]

  Gastrointestinal Disorders: Abdominal pain, abdominal distention, abdominal discomfort, dyspepsia, flatulence, gastroesophageal reflux disease, upper abdominal pain, vomiting. General Disorders: Fever, lethargy. Hepatobiliary Disorders: Hepatitis. [rxlist.com]

• Hypotension

  In more severe cases it can present with altered mental status, coma, hypotension, hypothermia and respiratory insufficiency. [calpoison.org]

  The Italian Medicines Agency recently released a safety recommendation on prescribing the drug and with regard to the existence of several conditions that contraindicate drug continuation, such as dehydration, infection, hypotension, surgery or hyperosmolar [ncbi.nlm.nih.gov]

  In addition, patients with an elevated lactate level in the absence of hypotension have mortality rates similar to those in patients with high lactate levels and hypotension refractory to fluid boluses, suggesting the presence of tissue hypoxia even in [mdedge.com]

• Osteoporosis

  Diseases associated with excessive acidity in the system are arthritis, gout, osteoporosis, infertility, cancers, depression, anxiety, insomnia, fibromyalgia, chronic fatigue syndrome, and skin problems such as psoriasis. [platinumenergysystems.ca]

  […] you have any other medical problems, especially: Bone fracture, history of or Kidney disease (eg, acute renal failure, Fanconi syndrome), history of or Liver disease (eg, hepatitis B infection), history of or Osteomalacia (soft bones), history of or Osteoporosis [drugs.com]

• Fracture

  This medicine may also increase your risk of developing fractures (broken bones). Ask your doctor about this if you or your child have any concerns. Your immune system may get stronger when you start using HIV medicines. [drugs.com]

  Available Completed Basic Science Type 1 Diabetes Mellitus With Hypoglycemia 1 Not Available Not Yet Recruiting Screening Actual Impaired Fluid Volume 1 Not Available Not Yet Recruiting Treatment Pain, Acute / Pain, Chest / Respiratory Failure / Rib Fracture [drugbank.ca]

• Withdrawn

  Following four subsequent operations, and the development of multiorgan failure, care was eventually withdrawn. [ncbi.nlm.nih.gov]

  Metformin was withdrawn only for the day of surgery. [medsafe.govt.nz]

  Phenformin, a previously used biguanide, as withdrawn from the market in the 1970’s due its association with numerous cases of lactic acidosis. [calpoison.org]

  The older related and now withdrawn drug phenformin carried a much higher risk of lactic acidosis. [en.wikipedia.org]

• Convulsions

  Intense exercise or convulsions can cause temporary cause lactic acidosis. [nlm.nih.gov]

  The brief and often very high lactate levels that occur with severe exercise or generalised convulsions (eg up to 30 mmol/l) are associated with an extremely low mortality rate. Indeed the mortality rate in these causes is usually extremely low. [anaesthesiamcq.com]

  Intense exercise or convulsions can cause temporary lactic acidosis. [medlineplus.gov]

  If the cause is convulsions from seizure activity, then treating the seizure is a critical step in treatment. Further supportive care must then be individualized. [ncbi.nlm.nih.gov]

  […] lactate (large capacity to clear) clinically there is often a combination of the above to produce a persistent lactic acidosis CAUSES (Cohen & Woods classification) Type A – Inadequate Oxygen Delivery anaerobic muscular activity (sprinting, generalised convulsions [lifeinthefastlane.com]

• Agitation

  On examination she was agitated and restless, with noted tachycardia and lungs were clear to auscultation with slightly rapid respirations. She is alert and oriented to person, place and time without rigidity or clonus. [calpoison.org]

  Symptoms of D-lactic Acidosis lack of muscle coordination (ataxia) balance and gait issues slurred speech (dysarthria) personality changes (grouchy, distant, angry, cold, hostile, aggressive, agitated, rarely – even abusive ) memory loss (and brain fog [theguthealthprotocol.com]

  Within 2 hours, the patient became agitated, his BP fell, and he required mechanical ventilation and medications to support his BP. [cjasn.asnjournals.org]

  […] face or mouth burning, crawling, itching, numbness, painful, prickling, "pins and needles", or tingling feelings in the hands, arms, feet, or legs chest pain clumsiness or unsteadiness stabbing pain weakness in the hands or feet Incidence not known Agitation [drugs.com]

  Other adverse effects reported are headache, agitation, dizziness, and tiredness. [cochranelibrary.com]

• Altered Mental Status

  CASE REPORT: The neurologic symptoms include altered mental status, slurred speech, and ataxia. Onset of neurological symptoms is accompanied by metabolic acidosis and high anion gap. [ncbi.nlm.nih.gov]

  In more severe cases it can present with altered mental status, coma, hypotension, hypothermia and respiratory insufficiency. [calpoison.org]

  After 40 days of receiving linezolid therapy, the patient's serum bicarbonate level was normal; however, 1 week later, she experienced nausea, vomiting, abdominal discomfort, and an altered mental status. [academic.oup.com]

• Somnolence

  We would also have considered adverse events among the outcomes, including peripheral neuropathy, somnolence, nausea, and hospitalisation. [dx.doi.org]

  Nervous: Somnolence. Psychiatric: Suicidal ideation, attempt, behavior, or completion. These events were observed primarily in subjects with a pre-existing history of depression or other psychiatric illness. Nightmare and sleep disorder. [rxlist.com]

• Stupor

  As the acid level goes up these symptoms progress to stupor, unconsciousness, coma, and death. The breath may have a fruity odor owing to the presence of acetone, and the patient may experience vomiting and diarrhea. [medical-dictionary.thefreedictionary.com]

The following diagnostic modalities and tests are implored in patients suspected of having lactic acidosis:

• Arterial blood gases (ABG): This test allows for the determination of blood pH and anion gap.
• Lactate assays: This kind of test determines the exact concentration of lactate in the blood and serum.
• Serum lactate levels: Venous or arterial serum samples are used to determine the levels of lactate in the blood. Lactate levels beyond 4-5 mmol/L is indicative for lactic acidosis. A 10% lactate clearance within 2 hours from the start of resuscitation is associated with a good prognosis [9].

• Hyperlactacidemia

  Test Details Use Hypoperfusion is the most common cause of lactic acidosis and hyperlactacidemia may be the only marker of tissue hypoperfusion. 1 Suspect lactic acidosis when unexplained anion gap metabolic acidosis is encountered, especially if azotemia [labcorp.com]

Patients diagnosed with lactic acidosis may benefit from the intravenous administration of sodium bicarbonate. This therapeutic intervention is proven to decrease the carbon dioxide concentration in the pulmonary artery and increase the pH of the serum. Some patients may be given dichloroacetate to stimulate the production of lactate dehydrogenase to eliminate the accumulation of lactate and pyruvate.

Carbicarb has used as a potent buffering agent for the treatment of acidemic events in the body. In the face of a worsening lactic acidosis with impending renal failure or cardiovascular failure, hemodialysis seem to be the only option to prevent fluid overload and the needless accumulation of carbon dioxide in the serum [10]. Patients may be given thiamine (vitamin B1) supplements to help oxidize serum acids.

Patients presenting with serum levels of lactate above 2.5 mmol/L are associated with an increased risk for morbidity and mortality [7]. Hyperlactatemia associated with anti-retroviral therapy hardly causes any mortality. However, critically ill patients with pH below 7.35 and serum level of lactate beyond 5 mmol/L have a very poor prognosis. Patients having hyperlactatemia with concurrent metabolic acidosis have more than double the risk of dying than those without indications for metabolic acidosis [8].

The following medical conditions can result in the accumulation of lactate in the serum:

• Intense exercise [1]
• Malignancies
• Acquired immune deficiency syndrome (AIDS)
• Renal failure
• Respiratory failure
• Sepsis
• Drugs and toxins
• Cardiac failure
• Anemia
• Carbon monoxide poisoning
• Diabetes mellitus
• Malaria
• Alcohol
• In born errors of metabolism [2]
• Hyperlactemia [3]
• Oral hypoglycemic agents [4]

The exact prevalence and incidence rate of lactic acidosis is hard to document for they usually occur in the critically ill patients who are sensitively unavailable for research interviews and examinations. Prevalence of lactic acidosis abounds in the high dependency areas of the hospitals [5]. There is an increasing trend in symptomatic lactic acidemia among patients under anti-retroviral therapy for AIDS [6]. Patient incidence rating reaches up to 35 cases per 1000 population under anti-retroviral regimens.

In general lactic acidosis appear in conjunction with several disease conditions that afflict mankind. The state of hyperlactatemia has been associated with the progression and deterioration of the underlying primary disease. In some medical condition like cardiopulmonary failure, lactic acidosis worsens as an effect of drugs and toxins used to allay the primary disease conditions. With severe and vigorous exercise, lactate accumulation is an imperative byproduct of the anaerobic respiration of the muscle cells. The body’s inability to keep up in naturally eliminating the lactic acid in the tissue causes the adverse symptoms of lactic acidosis. The progressive failure of the body’s acid buffering system to counteract the lactate accumulation has been elucidated as the primary culprit in lactic acidosis observed in intense exercise and intake of certain drugs.

The occurrence of lactic acidosis is easily preventable when there is a prompt diagnosis and therapeutic intervention done on the primary underlying illness. Athletes should do pre-activity stretching to avoid muscular injuries that might aggravate the accumulation of lactate in the muscles. A post-activity sports massage on the affected extremities will assist the rapid disposal of the lactic acid accumulation.

Alcohol use should be taken in moderation to avoid lactate accumulation in the serum. Diabetics and patients with impending cardiovascular disorders must submit to frequent physician’s follow-up and comply regularly with maintenance medications to avoid complications like lactic acidosis and metabolic acidosis. Patients with impending infection should be treated adequately with the appropriate antibiotic therapy to avoid the occurrence of septicemia. An annual tumor body scan to promptly diagnose ongoing and occult malignancies.

Lactic acidosis is a type of metabolic acidosis due to the inadequate disposal of lactic acid by the body leading to its accumulation in the serum. Lactate is a common byproduct of anaerobic respiration which is essentially cleared in the liver, kidneys, and the muscles. Lactic acidosis occurs when the natural buffering system of the body fails and serum pH falls below 7.25. Accumulation of lactate in the serum is also eminent at >2 mmol/L technically referred to as hyperlactataemia.

• Definition: Lactic acidosis is a type of metabolic acidosis brought about by the inadequate elimination of lactic acid by the body causing a decreased blood pH.
• Cause: Lactic acidosis can be brought about by factors like intense exercise and intake of certain kinds of drugs. Factors like kidney, respiratory, and heart failure can also lead to lactic acidosis. Uncontrolled sepsis with can lead to both lactic acidosis and metabolic acidosis. Malignancies can lead to the accumulation of acidic ions in the serum. 
• Symptoms: Patients with diagnosed lactic acidosis presents with nausea, tachypnea, hypotension, lethargy, oliguria, weakness, and confusion.
• Diagnosis: Lactic acidemic states are investigated upon using ABG, lactate assays, and serum lactate level determination.
• Treatment and follow-up: Patients suffering from lactic acidosis will benefit directly from the administration of sodium bicarbonate, dichloroacetate, and carbicarbs. Patients with kidney and heart failure can be alleviated with hemodialysis. Thiamine supplementation may be used as an oxidizing agent to treat the acidemic state. 

1. Vary TC, Drnevich D, Jurasinski C, Brennan WA Jr. Mechanisms regulating skeletal muscle glucose metabolism in sepsis. Shock. Jun 1995; 3(6):403-10.
2. Inborn Errors of Metabolism; Intensive Care Nursery House Staff Manual, UCSF Children's Hospital
3. Siegel JH, Cerra FB, Coleman B, et al. Physiological and metabolic correlations in human sepsis. Invited commentary. Surgery. Aug 1979; 86(2):163-93.
4. Salpeter SR, Greyber E, Pasternak GA, Salpeter Posthumous EE. Risk of fatal and nonfatal lactic acidosis with metformin use in type 2 diabetes mellitus. Cochrane Database Syst Rev. Jan 20 2010; CD002967.
5. Suistomaa M, Ruokonen E, Kari A, et al; Time-pattern of lactate and lactate to pyruvate ratio in the first 24 hours of intensive care emergency admissions. Shock. 2000 Jul; 14(1):8-12.
6. Hernandez Perez E, Dawood H; Stavudine-induced hyperlactatemia/lactic acidosis at a tertiary communicable diseases clinic in South Africa. J Int Assoc Physicians AIDS Care (Chic). 2010 Mar-Apr; 9(2):109-12. 
7. Gunnerson KJ, Saul M, He S, Kellum JA. Lactate versus non-lactate metabolic acidosis: a retrospective outcome evaluation of critically ill patients. Crit Care. Feb 10 2006; 10(1):R22.
8. Fall PJ, Szerlip HM. Lactic acidosis: from sour milk to septic shock. J Intensive Care Med. Sep-Oct 2005; 20(5):255-71.
9. Jones AE. Lactate clearance for assessing response to resuscitation in severe sepsis. Acad Emerg Med. Aug 2013; 20(8):844-7.
10. Finkle SN. Should dialysis be offered in all cases of metformin-associated lactic acidosis? Crit Care. 2009; 13(1):110.