D-lactic acidosis: a treatable encephalopathy in pediatric patients

Factors associated with D-lactic acidosis in pediatric intestinal failure: A case-control study

BACKGROUND

D-lactic acidosis (DLA) is a serious complication of short bowel syndrome (SBS) in children with intestinal failure (IF). Malabsorbed carbohydrates are metabolized by bacteria in the intestine to D-lactate which can lead to metabolic acidosis and neurologic symptoms.

METHODS

A retrospective chart review was performed in children ≤18 years old with SBS who had one of the following criteria: unexplained metabolic acidosis, neurologic signs or symptoms, history of antibiotic therapy for small bowel bacterial overgrowth, or high clinical suspicion of DLA. Cases had serum D-lactate concentration >0.25 mmol/L; controls with concentrations ≤0.25 mmol/L.

RESULTS

Of forty-six children, median age was 3.16 (interquartile range (IQR): 1.98, 5.82) years, and median residual bowel length was 40 (IQR: 25, 59) cm. There were 23 cases and 23 controls. Univariate analysis showed that cases had significantly lower median bicarbonate (19 vs. 24 mEq/L, p = 0.001), higher anion gap (17 vs. 14 mEq/L, p < 0.001) and were less likely to be receiving parenteral nutrition, compared with children without DLA. Multivariable analysis identified midgut volvulus, history of intestinal lengthening procedure, and anion gap as significant independent risk factors. Midgut volvulus was the strongest independent factor associated with DLA (adjusted odds ratio = 17.1, 95% CI: 2.21, 133, p = 0.007).

CONCLUSION

DLA is an important complication of pediatric IF due to SBS. Patients with IF, particularly those with history of midgut volvulus, having undergone intestinal lengthening, or with anion gap acidosis, should be closely monitored for DLA.

D-lactic acidosis in humans: systematic literature review

BACKGROUND

D-lactic acidosis is an uncommon and challenging form of metabolic acidosis that may develop in short bowel syndrome. It has been documented exclusively in case reports and small case series.

METHODS

We performed a review of the literature in the National Library of Medicine and Excerpta Medica databases.

RESULTS

We identified 84 original reports published between 1977 and 2017. D-lactic acidosis was observed in 98 individuals ranging in age from 7 months to 86 years with short bowel syndrome. The clinical presentation included Kussmaul breathing, confusion, slurred speech, and gait disturbances. Furthermore, among 99 consecutive patients with short bowel syndrome, 21 reported having episodes with symptoms consistent with D-lactic acidosis. In addition, D-lactic acid might also contribute to acidosis in diabetes mellitus. Finally, abnormally high D-lactic acid was documented after administration or ingestion of large amounts of propylene glycol, as paraneoplastic phenomenon and perhaps also in a so far poorly characterized inherited inborn error of metabolism.

CONCLUSIONS

In humans with short bowel syndrome (or carbohydrate malabsorption), D-lactic acidosis is likely rather common and under-recognized. This condition should be included in the differential diagnosis of unexplained high-gap metabolic acidosis where the anion causing the acidosis is not known. Furthermore, diabetic acidosis might be caused by accumulation of both ketone bodies and D-lactic acid. Finally, there are endogenous sources of D-lactic acid in subjects with propylene glycol intoxication.

Examining clinical similarities between myalgic encephalomyelitis/chronic fatigue syndrome and D-lactic acidosis: a systematic review

BACKGROUND

The pursuit for clarity in diagnostic and treatment pathways for the complex, chronic condition of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) continues. This systematic review raises a novel question to explore possible overlapping aetiology in two distinct conditions. Similar neurocognitive symptoms and evidence of D-lactate producing bacteria in ME/CFS raise questions about shared mechanisms with the acute condition of D-lactic acidosis (D-la).

METHODS

D-la case reports published between 1965 and March 2016 were reviewed for episodes describing both neurological symptoms and high D-lactate levels. Fifty-nine D-la episodes were included in the qualitative synthesis comparing D-la symptoms with ME/CFS diagnostic criteria. A narrative review of D-la mechanisms and relevance for ME/CFS was provided.

RESULTS

The majority of neurological disturbances reported in D-la episodes overlapped with ME/CFS symptoms. Of these, the most frequently reported D-la symptoms were motor disturbances that appear more prominent during severe presentations of ME/CFS. Both patient groups shared a history of gastrointestinal abnormalities and evidence of bacterial dysbiosis, although only preliminary evidence supported the role of lactate-producing bacteria in ME/CFS.

LIMITATIONS

Interpretation of results are constrained by both the breadth of symptoms included in ME/CFS diagnostic criteria and the conservative methodology used for D-la symptom classification. Several pathophysiological mechanisms in ME/CFS were not examined.

CONCLUSIONS

Shared symptomatology and underlying microbiota-gut-brain interactions raise the possibility of a continuum of acute (D-la) versus chronic (ME/CFS) presentations related to D-lactate absorption. Measurement of D-lactate in ME/CFS is needed to effectively evaluate whether subclinical D-lactate levels affect neurological symptoms in this clinical population.

D-lactic acidosis: an underrecognized complication of short bowel syndrome

D-lactic acidosis or D-lactate encephalopathy is a rare condition that occurs primarily in individuals who have a history of short bowel syndrome. The unabsorbed carbohydrates act as a substrate for colonic bacteria to form D-lactic acid among other organic acids. The acidic pH generated as a result of D-lactate production further propagates production of D-lactic acid, hence giving rise to a vicious cycle. D-lactic acid accumulation in the blood can cause neurologic symptoms such as delirium, ataxia, and slurred speech. Diagnosis is made by a combination of clinical and laboratory data including special assays for D-lactate. Treatment includes correcting the acidosis and decreasing substrate for D-lactate such as carbohydrates in meals. In addition, antibiotics can be used to clear colonic flora. Although newer techniques for diagnosis and treatment are being developed, clinical diagnosis still holds paramount importance, as there can be many confounders in the diagnosis as will be discussed subsequently.

A case of D-lactic acid encephalopathy associated with use of probiotics

A five year old girl was admitted to the hospital for evaluation of intermittent ataxia. She had undergone serial resections of the small intestine after birth, resulting in short bowel syndrome. Lactomin was prescribed for watery diarrhea at twice the regular dose 2 weeks before the onset of neurologic symptoms. D-lactic acidosis was diagnosed on the basis of a plasma D-lactate level of 5.537 mmol/l. Lactomin was discontinued, and she was treated with sodium bicarbonate and oral antibiotics. The probiotics the patient had taken were likely the cause of D-lactic acidosis and should therefore be avoided in patients with short bowel syndrome.

Nutritional management of infants with short bowel syndrome

The prevalence of short bowel syndrome appears to be increasing because of more aggressive surgical and medical approaches to the management of neonatal intraabdominal catastrophies. Hence, a large cohort of neonates with intestinal failure occupies neonatal intensive care units, requiring chronic total parenteral nutrition (TPN) in hopes that the residual bowel will adapt, thereby permitting weaning of TPN. Alternatively, when there is no hope for adaptation, these infants are maintained on TPN in hopes that they will grow to a size and state of general health satisfactory for either isolated intestinal transplant when liver function is preserved or combined liver-intestinal transplantation when the liver is irreparably damaged. Thus, it is imperative to provide enough parenteral nutrition to facilitate growth while minimizing TPN constituents predisposing to liver damage. Liver disease associated with intestinal failure (IFALD) seems to occur due to a variety of host factors combined with deleterious components of TPN. Host factors include an immature bile secretory mechanism, bile stasis due to fasting, and repeated septic episodes resulting in endotoxemia. Many constituents of TPN are associated with liver damage. Excessive glucose may result in fatty liver and/or hepatic fibrosis, excessive protein may lead to reduced bile flow, and phytosterols present in intravenous lipid may produce direct oxidant damage to the liver or may impede cholesterol synthesis and subsequent bile acid synthesis. Parenteral strategies employed to minimize TPN damage include reducing glucose infusion rates, reducing parenteral protein load, and reducing parenteral lipid load. Furthermore, preliminary studies suggest that fish oil-based lipid solutions may have a salutary effect on IFALD. Ultimately, provision of enteral nutrition is imperative for preventing or reversing IFALD as well as facilitating bowel adaptation. While studies of trophic hormones are ongoing, the most reliable current method to facilitate adaptation is to provide enteral nutrition. Continuous enteral feeding remains the mainstay of enteral nutrition support.

Small intestinal bacterial overgrowth: roles of antibiotics, prebiotics, and probiotics

Small intestinal bacterial overgrowth is common in intestinal failure. Its occurrence relates to alterations in intestinal anatomy, motility, and gastric acid secretion. Its presence may contribute to symptoms, mucosal injury, and malnutrition. Relationships between bacterial overgrowth and systemic sepsis are of potential importance in the intestinal failure patient because the direct translocation of bacteria across the intestinal epithelium may contribute to systemic sepsis: a phenomenon that has been well established in experimental animal models. The accurate diagnosis of bacterial overgrowth continues to present a number of challenges in clinical practice and especially so among patients with intestinal failure. The management of patients with bacterial overgrowth remains, for the most part, primarily empiric and comprises antibiotic therapy and correction of any associated nutritional deficiencies. Although evidence from experimental animal studies consistently indicates that probiotics exert barrier-enhancing, antibacterial, immune-modulating, and anti-inflammatory effects, which all could be benefits in small intestinal bacterial overgrowth and intestinal failure, their role in human beings remains to be evaluated adequately.

53-years-old with mental status changes

D-lactic acidosis, a complication of short bowel syndrome, presents with a variety of neurological symptoms and metabolic acidosis. Treatment is hydration, replacement of nutritional deficiency replacement, and selective antibiotics. Prevention entails complex carbohydrate diet and vitamin and mineral supplements.

D-lactic acidosis 23 years after jejuno-ileal bypass

Accumulation of D-lactate after gastrointestinal surgery, particularly jejuno-ileal bypass, is an uncommon and often misdiagnosed clinical disturbance. The syndrome may be complicated by dizziness, ataxia, confusion, headache, memory loss, and aggressive behavior. Serum chemistries are often deceptive because the anion gap is frequently normal in spite of severe metabolic acidosis. Moreover, the urine anion gap may be positive, incorrectly suggesting a defect in renal net acid excretion. Indeed, the combination of a normal anion gap metabolic acidosis and positive urine anion gap may erroneously suggest a diagnosis of renal tubular acidosis. Importantly, all reported cases of D-lactic acidosis secondary to bypass surgery have been encountered within 5 to 10 years following the surgery. Here we present an unusual case of D-lactic acidosis (complicated by encephalopathy) presenting 23 years after a jejuno-ileal bypass procedure. The patient was initially diagnosed with a drug intoxication secondary to benzodiazepines. Ultimately, the diagnosis of D-lactate encephalopathy was established after challenging the patient with a carbohydrate load. Thus, administration of 40 kcal/kg over 16 hours reproduced the clinical syndrome and was accompanied by a marked increment in serum and urine D-lactate concentration. The patient had sustained resolution of her symptoms after treatment with oral vancomycin.

Assay of D-lactate in urine of infants and children with reference values taking into account data below detection limit

Accumulation of D-lactic acid produced by intestinal bacteria such as streptococci and lactobacilli has been extensively studied in ruminants [1-4]. In humans an increased production of D-lactate by intestinal bacteria under pathological conditions such as the short bowel syndrome can cause metabolic acidosis [5-8]. Since the lactate assays routinely used only measure L-lactate we developed a sensitive method of D-lactate quantification and established reference values in spot urines of infants and children (0 to 4 years of age). The enzymatic method with fluorimetric quantification of NADH is linear up to 2 mmol/l. It has a detection limit of 3.4 micromol/l. Among structurally related organic acids an interference was found only for L-lactate and DL-2-hydroxybutyrate at concentrations which are way beyond their physiological excretion. One hundred and sixty five spot urines of healthy Swiss (S), Austrian (A), German (G) and Chilean (CHI) infants aged from 0 to 4 years were analyzed. The distribution of the data is close to a lognormal one. Values below the detection limit were simulated and age groups were formed. In all populations D-lactate excretion was found highest during the first year of life; it declines with age during infancy and remains stable from 2.5 to 4 years of age. We show that D-lactate is excreted physiologically by healthy infants and children below 4 years of age and present reference values for D-lactate excretion which show some differences between the populations tested.

D-lactic acidosis. A review of clinical presentation, biochemical features, and pathophysiologic mechanisms

This report describes a case of d-lactic acidosis observed by the authors and then reviews all case reports of d-lactic acidosis in the literature in order to define its clinical and biochemical features and pathogenetic mechanisms. The report also reviews the literature on metabolism of d-lactic acid in humans. The clinical presentation of d-lactic acidosis is characterized by episodes of encephalopathy and metabolic acidosis. The diagnosis should be considered in a patient who presents with metabolic acidosis and high serum anion gap, normal lactate level, negative Acetest, short bowel syndrome or other forms of malabsorption, and characteristic neurologic findings. Development of the syndrome requires the following conditions 1) carbohydrate malabsorption with increased delivery of nutrients to the colon, 2) colonic bacterial flora of a type that produces d-lactic acid, 3) ingestion of large amounts of carbohydrate, 4) diminished colonic motility, allowing time for nutrients in the colon to undergo bacterial fermentation, and 5) impaired d-lactate metabolism. In contrast to the initial assumption that d-lactic acid is not metabolized by humans, analysis of published data shows a substantial rate of metabolism of d-lactate by normal humans. Estimates based on these data suggest that impaired metabolism of d-lactate is almost a prerequisite for the development of the syndrome.

Organic acidurias and related abnormalities

Organic acid analysis is a powerful technique in the diagnosis of inborn errors of metabolism. Since the development of the technique over twenty-five years ago, it has evolved into a sophisticated and powerful method and is an essential tool in the diagnosis of the organic acidurias. The chemistry and biochemistry of organic acids, as well as sample preparation, instrumentation, and many aspects of the more commonly used methods for the analysis of these compounds, are reviewed. The biochemical and clinical characteristics of each of the primary organic acidurias are described. In addition, the various noninherited causes of secondary organic acidurias that lead to the excretion of abnormal organic acids are also described, and ways of differentiating primary from secondary causes are discussed.