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Lactic acidosis. Lactic acidosis associated with metformin use in treatment of type 2 diabetes mellitus.

Metformin, an antihyperglycemic, is widely used in the treatment of type 2 diabetes mellitus (DM). A rare, but important complication associated with this drug is the development of lactic acidosis: Overall mortality of lactic acidosis is approximately 50%. Certain subsets of patients taking metformin are at greater risk of developing lactic acidosis. This report discusses the development of metformin-associated lactic acidosis in four older adults admitted to an institution during a 2-month period, treatments, and outcomes. We recommend an aggressive treatment strategy of hemodialysis followed by peritoneal dialysis, continuous bicarbonate infusion, and tight glucose control. We review the cautions and contraindications of metformin use for the treatment of type 2 DM and report an educational plan for residents and staff instituted to improve drug complication awareness and reduce mortality.

Acidosis, Lactic↗

Lactic acidosis.

Lactic acid is generated as the end product of anaerobic metabolism of glucose and is disposed by gluconeogenesis or oxidation. Changes in the lactate pyruvate ratio are not necessarily indicative of tissue hypoxia. The plasma lactate concentration is the result of lactate production and lactate removal (hepatic and renal gluconeogenesis; oxidation by muscle, liver and kidney). Lactic acidosis is defined as a state of metabolic acidosis (arterial pH less than 7.3) due to an increase in the blood concentration of lactate (greater than 2 mEq/l). Lactic acidosis may occur with evidence of tissue hypoxemia (type A) or in its absence (type B). Lactic acidosis has been described in association with phenformin therapy, hereditary enzymatic defects, hematological malignancy, prolonged fasting, shock with or without septicemia and occasionally without any underlying disease ("idiopathic" lactic acidosis). The therapy of lactic acidosis consists of administration of sodium bicarbonate and restoration of adequate tissue perfusion; hemodialysis may be helpful to control sodium excess and possibly to remove phenformin. The effectiveness of methylene blue, glucose and insulin are not yet established.

Acidosis↗

Malignancy-induced lactic acidosis.

Lactic acidosis, a rare and usually fatal complication of malignancy, is defined as a clinical condition in which the pH is less than or equal to 7.35 and the serum lactate level greater than or equal to 5 mEq/L. We have described the clinical aspects of four cases of lactic acidosis associated with malignancy, and have reviewed all reported cases of lactic acidosis in malignancy meeting the criteria. Rapid recognition of the condition and prompt institution of chemotherapy led to reversal of lactic acidosis in three of our four patients, but long-term survival is related to the responsiveness of the underlying tumor.

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Mitochondrial tRNA gene mutations in patients having mitochondrial disease with lactic acidosis.

Lactic acidosis has been associated with a variety of clinical conditions and can be due to mutation in nuclear or mitochondrial genes. We performed mutations screening of all mitochondrial tRNA genes in 44 patients who referred as hyperlactic acidosis. Patients showed heterogeneous phenotypes including Leigh disease in four, MELAS in six, unclassified mitochondrial myopathy in 10, cardiomyopathy in five, MERRF in one, pure lactic acidosis in six, and others in 12 including facio-scaplo-femoral muscular dystrophy (FSFD), familial cerebellar ataxia, recurrent Reye syndrome, cerebral palsy with mental retardation. We measured enzymatic activities of pyruvate dehydrogenase complex, and respiratory chain enzymes. All mitochondrial tRNA genes and known mutation of ATPase 6 were studied by single strand conformation polymorphism (SSCP), automated DNA sequence and PCR-RFLP methods. We have found one patient with PDHC deficiency and six patients with Complex I+IV deficiency, though the most of the patients showed subnormal to deficient state of respiratory chain enzyme activities. We have identified one of the nucleotide changes in 29 patients. Single nucleotide changes in mitochondrial tRNA genes are found in 27 patients and one in ATPase 6 gene in two patients. One of four pathogenic point mutations (A3243G, C3303T, A8348G, and T8993G) was identified in 12 patients who showed the phenotype of Leigh syndrome, MELAS, cardimyopathy and cerebral palsy with epilepsy. Seventeen patients have one of the normal polymorphisms in the mitochondrial tRNA gene reported before. SSCP and PCR-RFLP could detect the heteroplasmic condition when the percentage of mutant up to 5, however, it cannot be observed by direct sequencing method. It is important to screen the mtDNA mutation not only by direct sequence but also by PCR-RFLP and the other sensitive methods to detect the heroplasmy when lactic acidosis has been documented in the patients who are not fulfilled the criteria of mitochondrial disorders.

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Evidence for a detrimental effect of bicarbonate therapy in hypoxic lactic acidosis.

Lactic acidosis, a clinical syndrome caused by the accumulation of lactic acid, is characterized by lactate concentration in blood greater than 5 mM. Therapy usually consists of intravenous sodium bicarbonate (NaHCO3), but resultant mortality is greater than 60 percent. The metabolic and systemic effects of NaHCO3 therapy of hypoxic lactic acidosis in dogs were studied and compared to the effects of sodium chloride or no therapy. Sodium bicarbonate elevated blood lactate concentrations to a greater extent than did either sodium chloride or no treatment. Despite the infusion of NaHCO3, both arterial pH and bicarbonate concentration decreased by a similar amount in all three groups of dogs. Additional detrimental effects of NaHCO3 were observed on the cardiovascular system, including decreases in cardiac output and blood pressure that were not observed with either sodium chloride or no treatment. Thus there is evidence for a harmful effect of NaHCO3 in the treatment of hypoxic lactic acidosis.

Acidosis↗

Unexpected survival from severe metformin-associated lactic acidosis.

Lactic acidosis is a recognised complication of the antihyperglycaemic biguanide agent metformin, especially in patients with renal failure. We report a case of severe lactic acidosis and hypothermia due to metformin treatment and renal impairment. The favourable outcome despite extremely unfavourable clinical signs and symptoms for survival after admission and initial treatment was unexpected. Specific aspects of the clinical course are addressed.

Acidosis, Lactic↗

Lactic acidosis.

Lactic acidosis is the most common metabolic acidosis. At clinical presentation, several causes usually can be identified. The liver is a major site of removal of lactate and hydrogen ions, and abnormalities in the aerobic metabolism of lactate by mitochondria in hepatocytes and other cells may contribute to many clinical conditions in which overproduction and underuse of lactate occur. To date, no therapy specifically designed to lower arterial blood lactate levels has reduced mortality significantly. Prompt recognition and treatment of the underlying causes of lactic acidosis remain the cornerstone of treatment.

Acidosis, Lactic↗

Sodium bicarbonate for the treatment of lactic acidosis.

Lactic acidosis often challenges the intensivist and is associated with a strikingly high mortality. Treatment involves discerning and correcting its underlying cause, ensuring adequate oxygen delivery to tissues, reducing oxygen demand through sedation and mechanical ventilation, and (most controversially) attempting to alkalinize the blood with IV sodium bicarbonate. Here we review the literature to answer the following questions: Is a low pH bad? Can sodium bicarbonate raise the pH in vivo? Does increasing the blood pH with sodium bicarbonate have any salutary effects? Does sodium bicarbonate have negative side effects? We find that the oft-cited rationale for bicarbonate use, that it might ameliorate the hemodynamic depression of metabolic acidemia, has been disproved convincingly. Further, given the lack of evidence supporting its use, we cannot condone bicarbonate administration for patients with lactic acidosis, regardless of the degree of acidemia.

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Human immunodeficiency virus infection with human granulocytic ehrlichiosis complicated by symptomatic lactic acidosis.

Lactic acidosis has been reported as a complication associated with antiretroviral therapy; in particular, usually with use of nucleoside reverse-transcriptase inhibitors. We describe a human immunodeficiency virus (HIV)-infected patient with a history of lipodystrophy who presented with hepatic insult associated with documented human granulocytic ehrlichiosis (HGE). Despite a normal serum lactate level before the onset of acute coinfection, the patient developed symptomatic hyperlactatemia while receiving appropriate treatment for HGE. To date, this is the first presentation of symptomatic hyperlactatemia in a patient with HIV infection and HGE.

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Glucose therapy of recurrent lactic acidosis.

Lactic acidosis not associated with hypoxic states has a high morbidity and mortality. Treatment of this condition has been supportive and the etiology poorly understood. We report a case of recurrent lactic acidosis in a patient with renal and hepatic insufficiency with hypoglycemia which was repeatedly reversed by restoring the glucose concentration to normal. This case and several others in the literature suggest a mechanism for the development of type II B hyperlactatemia and new approaches for therapy.

Acidosis↗

[Lactic acidosis].

Lactic acidosis is a metabolic disturbance characterized by an increase of the production/clearance ratio of lactate. Lactate is a catabolite of glycolysis when this takes place under anaerobic conditions. Clinically LA is characterized by: signs of acidosis, venous blood lactate greater than 5 mMol/l, arterial pH less than 7.25. LA is classified in type A, due to shock, and type B which, in turn, can be divided according to its pathogenesis in B1 correlated to particular pathologies, B2 due to exogenous substances and B3 caused by congenital metabolic diseases. LA is of particular interest in type II diabetes mellitus treated by phenformin. Current therapeutic directions, although suboptimal, are: to eliminate the causes of lactate hyperproduction by maintaining a sufficient efficiency of the cardio-vascular apparatus, to correct acidosis by using alkalinizing solutions, to remove pharmacologically or by dialysis the excess of lactate.

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Natural history and course of acquired lactic acidosis in adults. DCA-Lactic Acidosis Study Group.

STUDY OBJECTIVE: To determine the pathogenesis and clinical course of lactic acidosis in adults receiving standard medical care. DESIGN: Placebo arm of a 5-year prospective, randomized, blinded study comparing placebo and dichloroacetate as specific lactate-lowering therapy. Each patient received intravenous saline placebo in addition to conventional therapy. SETTING: Intensive care units of 10 tertiary care hospitals in North America. PATIENTS: One hundred twenty-six patients with lactic acidosis, defined as arterial blood lactate greater than or equal to 5 mmol/L and either arterial pH of less than or equal to 7.35 or base deficit greater than 6 mmol/L. Patients were followed for up to 6 months. MEASUREMENTS AND MAIN RESULTS: Mean +/- SD demographic entry data for 126 patients included: age 56 +/- 17 years, lactate 10.4 +/- 5.5 mmol/L, pH 7.24 +/- 0.14, calculated base deficit 14.1 +/- 5.4, arterial systolic blood pressure 103 +/- 29 mm Hg, Glasgow Coma score 7.9 +/- 4.9, and APACHE II score 19.2 +/- 8.1. Despite fluids and pressors, 32% of patients had systolic blood pressures of less than or equal to 90 mm Hg in association with sepsis (59%), cardiac failure (18%), or hemorrhage (18%). The most common causes of lactic acidosis in the absence of shock were sepsis (49%), liver disease (15%), and respiratory failure (12%). The median survival was 38.5 hours. Survival at 24 hours was 59%. Arterial pH predicted 24-hour survival better than base deficit or bicarbonate level. Percent survival was 41% at 3 days and 17% at 30 days. Only 21% of patients survived to leave the intensive care unit, and 17% were discharged from the hospital. In patients receiving sodium bicarbonate, neither acid-base nor hemodynamic status improved. CONCLUSIONS: In this first prospective study of the clinical course of acute lactic acidosis in adults, nearly all subjects had both hemodynamic and nonhemodynamic (metabolic) underlying causes, many of which independently predicted survival and most of which were refractory to standard care.

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A controlled clinical trial of dichloroacetate for treatment of lactic acidosis in adults. The Dichloroacetate-Lactic Acidosis Study Group.

BACKGROUND: Mortality is very high in lactic acidosis, and there is no satisfactory treatment other than treatment of the underlying cause. Uncontrolled studies have suggested that dichloroacetate, which stimulates the oxidation of lactate to acetyl-coenzyme A and carbon dioxide, might reduce morbidity and improve survival among patients with this condition. METHODS: We conducted a placebo-controlled, randomized trial of intravenous sodium dichloroacetate therapy in 252 patients with lactic acidosis; 126 were assigned to receive dichloroacetate and 126 to receive placebo. The entry criteria included an arterial-blood lactate concentration of > or = 5.0 mmol per liter and either an arterial-blood pH of < or = 7.35 or a base deficit of > or = 6 mmol per liter. The mean (+/- SD) arterial-blood lactate concentrations before treatment were 11.6 +/- 7.0 mmol per liter in the dichloroacetate-treated patients and 10.4 +/- 5.5 mmol per liter in the placebo group, and the mean initial arterial-blood pH values were 7.24 +/- 0.12 and 7.24 +/- 0.13, respectively. Eighty-six percent of the patients required mechanical ventilation, and 74 percent required pressor agents, inotropic drugs, or both because of hypotension. RESULTS: The arterial-blood lactate concentration decreased 20 percent or more in 83 (66 percent) of the 126 patients who received dichloroacetate and 45 (36 percent) of the 126 patients who received placebo (P = 0.001). The arterial-blood pH also increased more in the dichloroacetate-treated patients (P = 0.005). The absolute magnitude of the differences was small, however, and they were not associated with improvement in hemodynamics or survival. Only 12 percent of the dichloroacetate-treated patients and 17 percent of the placebo patients survived to be discharged from the hospital. CONCLUSIONS: Dichloroacetate treatment of patients with severe lactic acidosis results in statistically significant but clinically unimportant changes in arterial-blood lactate concentrations and pH and fails to alter either hemodynamics or survival.

Acidosis, Lactic↗

Treatment of lactic acidosis.

Severe lactic acidosis is often associated with poor prognosis. Recognition and correction of the underlying process is the major step in the treatment of this serious condition. Intravenous administration of sodium bicarbonate has been the mainstay in the treatment of lactic acidosis. Aggressive use of this therapeutic modality, however, can lead to serious complications and should therefore be considered with caution. Peritoneal dialysis and hemodialysis provide large amounts of alkali without causing the hypernatremia or hypervolemia commonly associated with bicarbonate infusion. Peritoneal dialysis with bicarbonate-based dialysate, in particular, appears to be an ideal means of delivering physiologic buffer. Administration of methylene blue was initially thought to increase lactate metabolism by altering the cellular oxidative state. Its subsequent clinical use, however, showed little efficacy. Sodium nitroprusside has been advocated for the treatment of some forms of lactic acidosis as a method of alleviating regional hypoperfusion. Insulin therapy has been found to be quite useful in the treatment of phenformin-associated lactic acidosis and is recommended in this setting. Since dichloroacetate activates pyruvate dehydrogenase and enhances lactate metabolism, it may be a useful adjunct in the treatment of lactic acidosis.

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[Biguanide-induced and - associated lactic acidosis: serum and tissue biguanide levels in hyperlactaemia and lactic acidosis (author's transl)].

An investigation was carried out on 30 diabetic patients in an attempt to clarify the relationship between serum biguanide levels and raised lactate. No consistent relationship was demonstrable between the serum biguanide level, administered dosage and time of administration. There was also no correlation between biguanide and lactate increase. It is not justifiable to quote a specific serum level of biguanides in defining lactic acidosis. A causal association between biguanide medication and lactic acidosis seems to be possible only by determination of serum and tissue levels. Determination of biguanide levels was carried out in the serum and tissue of a patient who had died as a result of lactic acidosis after phenformin administration. While the serum levels were only slightly higher than the therapeutic range, both liver and kidney tissue showed highly toxic levels. Furthermore, the amount of biguanides in the body was calculated in another patient successfully treated for lactic acidosis after buformin therapy. A differentiation should be made between biguanide-induced and biguanide-associated lactic acidosis. In both forms serum levels can be within relatively low ranges. In the former condition, the biguanides alone are responsible for the development of lactic acidosis by blocking the respiratory chain. In the latter condition they aggravate an already existing pathological condition, and can, therefore, represent a lethal factor.

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Lactic acidosis in metformin therapy: searching for a link with metformin in reports of 'metformin-associated lactic acidosis'.

OBJECTIVE: The link between metformin and lactic acidosis in metformin therapy may be causal, associated or coincidental. Our objective was to investigate this link by studying and analysing published reports of so-called 'metformin-associated lactic acidosis'. RESEARCH DESIGN AND METHODS: systematically searched in the BIOSIS, DERWENT, EMBASE, MEDLINE, and PASCAL databases of the English language and non-English language literature for all reports of so-called 'metformin-associated lactic acidosis' published from May 1995 through January 2000. We did not include reports related to metformin overdose or contrast media-induced renal failure. Metformin accumulation and concurrent pathologies were critically reviewed as precipitating factors for metformin-associated lactic acidosis. Metformin accumulation was assessed in terms of the recorded measurement of metformin concentration in plasma or, if not available, by the presence of primary renal failure, i.e. renal failure that was not secondary to a shock syndrome. RESULTS: We found 21 reports describing a total of 26 patients. Criteria of lactic acidosis (lactate > 5 mmol/l, pH <or= 7.35) were not met in four patients. In the remaining 22 patients, plasma metformin concentration was determined in only four, of whom one had a normal value. In the 18 patients with lactic acidosis where plasma metformin concentration data was not available, the presence of primary renal failure was absent or unlikely in six patients, uncertain in two, and likely or proven in 14. With regard to these 14 patients, the precipitating factor was metformin in 12 patients (in the context of renal failure either chronic or acute) and intercurrent pathologies in two others. Overall, lactic acidosis was either absent (n = 4), precipitated by concurrent pathology (n = 8), precipitated by metformin without apparent associated pathology (n = 12) or of uncertain origin (n = 2). Death occurred 10 times but only once in the 12 patients with metformin-induced lactic acidosis and this was not related to metformin. CONCLUSIONS: While the term 'metformin-associated lactic acidosis' is commonly used to depict all situations of lactic acidosis in metformin therapy, true metformin-associated lactic acidosis, i.e. one which refers to metformin and concurrent pathologies as co-precipitating factors, was never observed in the studied reports. As there was no mortality due to metformin alone, it is important that physicians are familiar with the range of other risk factors that contribute to lactic acidosis in patients treated with metformin.

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Risk of fatal and nonfatal lactic acidosis with metformin use in type 2 diabetes mellitus.

BACKGROUND: Metformin is an oral anti-hyperglycemic agent used in the treatment of type 2 diabetes mellitus. The results of the UK Prospective Diabetes Study indicate that metformin treatment is associated with a reduction in total mortality compared to other anti-hyperglycemic treatments. Metformin, however, is thought to increase the risk of lactic acidosis, and is considered to be contraindicated in many chronic hypoxemic conditions that may be associated with lactic acidosis, such as cardiovascular, renal, hepatic and pulmonary disease, and advancing age. OBJECTIVES: To assess the incidence of fatal and nonfatal lactic acidosis with metformin use compared to placebo and other glucose-lowering treatments in patients with type 2 diabetes mellitus. A secondary objective was to evaluate the blood lactate levels for those on metformin treatment compared to placebo or non-metformin therapies. SEARCH STRATEGY: A search was performed of the Cochrane Controlled Trials Register and the Database of Abstracts of Reviews of Effectiveness (up to 4/2000), Medline (up to 11/2000), Embase (up to 11/2000), Oldmedline, and Reactions (up to 5/2000), in order to identify all studies of metformin treatment from 1966 to November 2000. The Cumulated Index Medicus was used to search relevant articles from 1959 to 1965. The search was augmented by scanning references of identified articles, and by contacting principal investigators. Date of latest search: November 2000. SELECTION CRITERIA: Prospective trials in patients with type 2 diabetes that lasted longer than one month were included if they evaluated metformin, alone or in combination with other treatments, compared to placebo or any other glucose-lowering therapy. Observational cohort studies of metformin treatment lasting greater than one month were also included. DATA COLLECTION AND ANALYSIS: Two reviewers independently selected trials to be included, assessed study quality and extracted data. The incidence of fatal and nonfatal lactic acidosis was recorded as cases per patient-years, for metformin treatment and for placebo or other treatments. The upper limit for the true incidence of cases in the metformin and non-metformin groups were calculated using Poisson statistics. In a second analysis lactate levels were measured as a net change from baseline or as mean treatment values (basal and stimulated by food or exercise) for treatment and comparison groups. The pooled results were recorded as a weighted mean difference (WMD) in mmol/L, using the fixed effects model for continuous data. MAIN RESULTS: Pooled data from 176 comparative trials and cohort studies revealed no cases of fatal or nonfatal lactic acidosis in 35,619 patient-years of metformin use or in 30,002 patients-years in the non-metformin group. Using Poisson statistics with 95% confidence intervals the upper limit for the true incidence of metformin-associated lactic acidosis was 8.4 cases per 100,000 patient-years, and the upper limit for the true incidence of lactic acidosis in the non-metformin group was 9 cases per 100,000 patient-years. There was no difference in lactate levels, either as mean treatment levels or as a net change from baseline, for metformin compared to placebo or other non-biguanide therapies. The mean lactate levels were slightly lower for metformin treatment compared to phenformin (WMD -0.75 mmol/L, 95% CI -0.86 to -0.15). REVIEWER'S CONCLUSIONS: There is no evidence from prospective comparative trials or from observational cohort studies that metformin is associated with an increased risk of lactic acidosis, or with increased levels of lactate, compared to other anti-hyperglycemic treatments if prescribed under the study conditions, taking into account contra-indications.

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Positron emission tomography and magnetic resonance spectroscopy of cerebral glycolysis in children with congenital lactic acidosis.

Congenital lactic acidosis with neurological symptoms may be due to a variety of disorders of energy metabolism. We investigated whether positron emission tomography (PET) and proton magnetic resonance spectroscopy (1H MRS) are capable of demonstrating specific changes to facilitate diagnosis. A corresponding increase of cerebral lactate (with MRS) and rate of glycolysis (with PET) was observed in 2 children with biochemical evidence of defective mitochondrial respiration. No such increase was noted in a child with lactic acidosis due to stress and exercise but normal respiratory chain activity, and in a control case with an epilepsy syndrome without evidence of primary changes of energy metabolism. The results suggest that defects of oxidative phosphorylation may cause a massive increase of glycolysis to cover energy requirements, with corresponding accumulation of lactate in brain tissue. This mechanism can now be demonstrated in vivo and, with further experience, may potentially be used as a diagnostic marker of respiratory chain disorders in brain tissue.

Acidosis, Lactic↗