[Epidemiological, clinical and evolutionary particularities of primary distal tubular acidosis in Tunisian children]. / Particularités épidémiologiques, cliniques et évolutives de l'acidose tubulaire distale primitive chez l'enfant tunisien.

INTRODUCTION: The distal renal tubular acidosis of children is characterized by hyperchloremic metabolic acidosis with normal anion gap, hypokalemia, hypercalciuria and nephrocalcinosis. It is secondary to the inability of alpha intercalar cells of the distal tubule to acidify urine of genetic origin. OBJECTIVE: To analyse the epidemiological aspects of distal tubular acidosis in Tunisia and study its evolutionary profile. PATIENTS AND METHODS: We conducted a retrospective descriptive study involving 44 patients followed at the paediatrics department of the Charles Nicolle Hospital in Tunis for 28 years (1991-2018). RESULTS: The most common discovery circumstances were growth retardation (88.6%), dehydration (56.8%), ployuro-polydipsic syndrome (47.7%), vomiting (40.9%) and nephrocalcinosis (38.6%). Growth retardation was found in 52.3% of patients. Dehydration was diagnosed in 59.1% of patients on the first exam. Polyuria was constant with an average diuresis of 8 cc/kg/h. All patients had the complete form of distal renal tubular acidosis with an average alkaline reserve of 11.1 mmol/L. Nephocalcinosis was found in 77.3% associated with nepholithiasis in 22.7%. Twenty-four patients had sensorineural deafness, nine of whom had ATP6V1B1/2p13 mutation. The ATP6V0A4/7q33-34 mutation was present in two patients. We used a high alkaline treatment dose with an average maintenance dose of 8.17 mmol/kg/24 hours. In the long term, stunting persisted in 34% of patients. The mean of creatinine's clearance at the last evaluation was 89.38 mL/min/1.73 m2 SC with stage 2 of chronic kidney disease in 50% of patients. CONCLUSION: Distal renal tubular acidosis has long been considered a benign pathology but is responsible for a progressive decline in GFD. Adequate metabolic control is needed to stabilize kidney function.

[Lactic Acidosis and Other Misunderstandings]. / Die Lactatazidose und andere Missverständnisse.

Lactic Acidosis and Other Misunderstandings Abstract. Lactic acidosis is a frequently encountered clinical problem in intensive care medicine. Nevertheless, many of the underlying biochemical processes are insufficiently understood, which leads to various misconceptions. Physiologically, lactate is an important, continuously produced carrier of energy and by no means a metabolic 'waste product'. Lactate is the corresponding base to lactic acid and is produced directly from pyruvate. In this reaction H+ is consumed and therefore lactate production itself cannot be directly responsible for the simultaneously arising acidosis. An elevated lactate level allows no conclusions about the underlying pathophysiological process, and, more importantly, it is not an appropriate marker for tissue oxygenation.

[Dietary control of metabolic acidosis in chronic kidney disease]. / Contrôle diététique de l'acidose métabolique chez le patient insuffisant rénal chronique.

Metabolic acidosis is a frequent complication of chronic kidney disease. Although it is known to appear at advanced stages, many studies suggest a state of "global protonic retention" starting at early stages of the disease, responsible of tissue damage, particularly musculoskeletal, alteration of protidic metabolism and endocrine disorders, promoting malnutrition and chronic inflammation, and finally increasing mortality. The majority of international recommandations suggest of supplementation by alkali, most of the time by sodium bicarbonate, to struggle against this complication. An interesting alternative to correct acidosis would consist on the modulation of the endogenous production of acid by playing with the alimentary incomes. In fact, it has been demonstrated that some different types of food produce or consume protons during their metabolism. Low protein diet and rich fresh fruits and vegetables diet would manage to correct at least as well as the supplementation by sodium bicarbonate the metabolic acidosis, and to struggle against its complications, noteworthy by slowing the decline of glomerular filtration rate by limiting the toxic adaptative fibrotic mechanisms, demonstrated by the decrease of urinary tubulo-interstitial suffering markers. Of the condition of being well led, those diets do not seem to expose patients to an over-risk of malnutrition or hyperkaliemia. They therefore appear to be an attractive alternative, efficiency and safe, to fight against chronic kidney disease metabolic acidosis and its complications.

[Acetaminophen induced 5-oxoproline acidosis: An uncommon case of high anion gap metabolic acidosis]. / Acidose à la 5-oxoproline induite par le paracétamol : une cause rare d'acidose métabolique à trou anionique augmenté.

The most common causes of high anion gap metabolic acidosis (HAGMA) are lactic acidosis, ketoacidosis, and intoxications. Nevertheless, clinicians can be faced with unexplained HAGMA, with a need to look for less common etiologies. We describe a case of 5-oxoproline (pyroglutamate) acidosis due to chronic acetaminophen ingestion at therapeutic dose in a 79-year-old inpatient. The pathophysiology of this condition is detailed, with abnormalities in the gamma-glutamyl cycle due to acetaminophen ingestion and severe chronic morbidities, resulting in glutathione and cysteine deficiency and then accumulation of 5-oxoproline. In HAGMA, when usual causes have been excluded, 5-oxoproline acidosis should be suspected in patients with chronic morbidities and acetaminophen ingestion. This diagnosis should be kept in mind because it generally resolves quickly with cessation of acetaminophen and administration of intravenous fluids.

[Metabolic complications of chronic kidney disease]. / Complications métaboliques de l'insuffisance rénale chronique.

Patients with Chronic Kidney Disease (CKD) are at risk of various metabolic complications, which can lead to health issues and even be life-threatening if not correctly treated, whereas they can be anticipated. Through clinical cases of patients taken from the daily practice, we propose to look into three of these common complications, namely hypocalcemia, hyperkalemia and metabolic acidosis. From the diagnostic approach to the patient care, these cases provide the opportunity to recall the fundamentals of these disorders and to present the recent literature date enlightening the knowledge related to them.

Neonatal metabolic acidosis at birth: In search of a reliable marker.

OBJECTIVE: A newborn may present acidemia on the umbilical artery blood which can result from respiratory acidosis or metabolic acidosis or be of mixed origin. Currently, in the absence of a satisfactory definition, the challenge is to determine the most accurate marker for metabolic acidosis, which can be deleterious for the neonate. METHODS: We reviewed the methodological and physiological aspects of the perinatal literature to search for the best marker of NMA. RESULTS: Base deficit and pH have been criticized as the standard criteria to predict outcome. The proposed threshold of pathogenicity is not based on convincing studies. The algorithms of various blood gas analyzers differ and do not take into account the specific neonatal acid-base profile. CONCLUSION: Birth-related neonatal eucapnic pH is described as the most pertinent marker of NMA at birth. The various means of calculating this value and the level below which it seems to play a possible pathogenic role are presented.

[Neonatal eucapnic pH at birth: Application in a cohort of 5392 neonates]. / Le pH eucapnique néonatal à la naissance : application à une cohorte de 5392 nouveau-nés.

OBJECTIVE: To apply a newly concept of neonatal eucapnic pH at birth [pH euc (n)] and compare its contribution towards conventional criteria of severe metabolic acidosis. METHODS: Analysis of a cohort of 5392 neonates from 2010 to 2014 in a level 1 maternity. clinical data (birth weight, gestational age, mode of delivery, APGAR score) were collected from archived files. Biological data were collected from umbilical cord blood, consisting of pH, PCO2, Base deficit, lactate. Eucapnic pH and eucapnic base deficit were calculated from pH and PCO2 with the Henderson-Hasselbalch equation applied in the Charles-Racinet diagram and/or with an Excel spreadsheet. RESULTS: Data set the prevalence of neonatal acidemia<7.00 to 0.62 %. The current cohort shows 32 cases of severe neonatal metabolic acidosis according to ACOG-AAP (2014) criteria and 26/29 cases according to McLennan (2015) criteria, of which 80 % were born by cesarean section or instrumental delivery. In 55 % of cases, calculated eucapnic pH at birth did not confirm the severity of metabolic acidosis based on a threshold set at 7.11. Five cases were transferred in neonatalogy only on clinical considerations of poor neonatal adaptation but not on biological consideration (pH euc<7.11 was equally distributed between transferred and non-transferred neonates, P=0.76; the same distribution was observed with the pH, P=0.20) and followed normal outcome. DISCUSSION AND CONCLUSION: The pH determination provides information only on the degree of acidemia and not on respiratory and/or metabolic components. Moreover, hypercapnia always present at birth is not included in the instructions to determine a metabolic acidosis (The American College of Obstetricians and Gynecologists, 2014; MacLennan et al., 2015). The new concept of neonatal eucapnic pH at birth accounts for only the metabolic component. We feel it should fine tune indications for cerebral hypothermia and thus improve its effectiveness. From a medicolegal perspective, for cases of cerebral palsy, it often allows to refute metabolic acidosis in perpartum events, often wrongfully being linked to generate cerebral injuries.

[Chronic renal failure: what is the optimal diet?]. / L'insuffisance rénale chronique: quelle est la diète optimale?

The optimal diet for chronic kidney disease (CKD) is an issue frequently brought up by patients and/or their relatives during outpatient visits. For patients without malnutrition who are motivated and supported by an experienced multidisciplinary team, the optimal protein intake of 0,6 g/kg of ideal body weight/day is recommended to halt the progression of CKD. A calorie intake of 30 to 35 kcal/kg of ideal body weight/day is necessary to reduce the risk of malnutrition from a low protein diet and to maintain a neutral nitrogen balance. A low-salt diet, namely 5 to 6 g/d, is useful to optimize the treatment of hypertension associated with CKD and to limit fluid overload. At the advanced stage of CKD, it is also necessary to restrict the intake of phosphorus and sometimes potassium. Given the complexity of optimal renal diet, coordination between general practitioners, nephrologists and dietitians is essential to foster optimal care.

La diète optimale pour la maladie rénale chronique (MRC) est un thème fréquemment discuté par les patients en consultation ambulatoire et/ou par leurs proches. Une diète optimale en protéines, réduite à 0,6 g/kg de poids idéal par jour est proposée pour ralentir la progression de la MRC chez des patients non dénutris, motivés et supportés par une équipe multidisciplinaire et expérimentée. Un apport calorique de 30 à 35 kcal/j est nécessaire pour limiter le risque de dénutrition par une diète pauvre en protéines et pour maintenir une balance azotée neutre. Une diète pauvre en sel, soit 5 à 6 g/jour, est utile pour optimaliser le traitement de l'hypertension artérielle associée à la MRC et pour limiter la surcharge hydrosodée. Lorsque la MRC est avancée, il est nécessaire de limiter également l'apport en phosphore et parfois celui en potassium. Compte tenu de la complexité de la diète rénale optimale, une coordination entre les praticiens, les néphrologues et les diététicien(ne)s est indispensable pour favoriser la prise en charge.

False hyperlactatemia in life-threatening ethylene glycol poisoning.

Ethylene glycol poisoning is rare, but prompt diagnosis is crucial, in order to initiate specific treatments. Herein, we report the case of a patient who was admitted to ICU for coma and extreme metabolic acidosis with unexpected hyperlactatemia on initial ICU blood gas analyzer. Ethylene glycol poisoning was diagnosed, and hyperlactatemia was ruled out on a blood sample sent to the biochemistry department. Interference of blood gas analyzers lactate electrodes with metabolites of ethylene glycol were the source of this apparent hyperlactatemia. Symptoms gradually improved and false hyperlactatemia resolved after renal replacement therapy and fomepizole administration. Time course of ethylene glycol concentration showed similar evolution. After initial confirmation of ethylene glycol presence, this biological interference could thus be used as a surrogate of costly and highly specialised dosages.

[Correlation between fetal scalp samples and umbilical cord samples]. / Corrélation entre prélèvements au scalp fœtal et prélèvements artériels au cordon.

OBJECTIVE: The objective was to evaluate the correlation between fetal scalp base excess (BE) and umbilical cord BE. Respective value of fetal scalp pH, BE and lactate for the prediction of neonatal metabolic acidosis were also evaluated. METHODS: A retrospective monocentric study was conducted in a French tertiary care academic maternity. All the patients who had a fetal scalp sampling during labor in 2010, less than 90 minutes before delivery were included. Fetal heart rate abnormalities (FHRA) were classified by degree of severity, according to the French guidelines. The differences between fetal scalp samples and umbilical cord samples over time and in relation with the type of FHRA were analyzed for pH and BE. The differences between fetal scalp pH and cord pH over time and in relation with scalp BE were analyzed. The correlation between fetal scalp samples and cord samples for pH, BE and lactate was estimated. Receiver operating characteristics (ROC) curves for fetal scalp pH, lactate and BE to predict umbilical cord pH under 7.20 were calculated. RESULTS: Seventy-one cases were included. The difference between fetal scalp sample and cord sample was lower when the sample was made closest to delivery both for pH and BE. The gravity of FHRA was not predictive of a faster decrease of pH or BE over time. The correlation was significant for pH (r=0.23, p=0.03) between scalp samples and cord samples, as for BE (r=0.49, p=0.001) and lactate (r=0.52, p=0.001). The ROC curves for pH, BE and lactate displayed a similar pattern. CONCLUSION: Fetal scalp and umbilical cord samples, for pH, BE and lactate were significantly correlated but their respective predictive value for cord pH less or equal to 7.20 was poor.

[Acid-base homeostasis: metabolic acidosis and metabolic alkalosis]. / Équilibre acidobasique: acidoses et alcaloses métaboliques.

Acid-base homeostasis ensured by the kidneys, which maintain the equilibrium between proton generation by cellular metabolism and proton excretion in urine. This requirement is lifesaving because of the protons' ability to bind to anionic proteins in the extracellular space, modifying their structure and functions. The kidneys also regenerate bicarbonates. The kidney is not the sole organ in charge of maintaining blood pH in a very narrow range; lungs are also involved since they allow a large amount of volatile acid generated by cellular respiration to be eliminated.

[Diagnosis of neonatal metabolic acidosis by eucapnic pH determination]. / Diagnostic de l'acidose métabolique à la naissance par la détermination du pH eucapnique.

UNLABELLED: The identification of a metabolic acidosis is a key criterion for establishing a causal relationship between fetal perpartum asphyxia and neonatal encephalopathy and/or cerebral palsy. The diagnostic criteria currently used (pH and base deficit or lactatemia) are imprecise and non-specific. OBJECTIVE: The study aimed to determine among a low-risk cohort of infants born at term (n = 867), the best diagnostic tool of metabolic acidosis in the cordonal from the following parameters: pH, blood gases and lactate values at birth. MATERIALS AND METHODS: The data were obtained from arterial blood of the umbilical cord by a blood gas analyser. The parameter best predicting metabolic analysis was estimated from the partial correlations established between the most relevant parameters. RESULTS: The results showed a slight change in all parameters compared to adult values: acidemia (pH: 7.28 ± 0.01), hypercapnia (56.5 ± 1.59 mmHg) and hyperlactatemia (3.4 ± 0.05 mmol/L). From partial correlation analysis, pCO(2) emerged to be the main contributor of acidemia, while lactatemia was shown to be non-specific for metabolic acidosis. Seven cases (0.81 %) showed a pH less than 7.00 with marked hypercapnia. The correction of this respiratory component by EISENBERG's method led to the eucapnic pH, classifying six out of seven cases as exclusive respiratory acidosis. DISCUSSION AND CONCLUSION: It has been demonstrated that the criteria from ACOG-AAP for defining a metabolic acidosis are incomplete, imprecise and generating errors in excess. The same is true for lactatemia, whose physiological significance has been completely revised, challenging the misconception of lactic acidosis as a specific marker of hypoxia. It appeared that eucapnic pH was the best way for obtaining a reliable diagnosis of metabolic acidosis. We proposed to adopt a simple decision scheme for determining whether a metabolic acidosis has occurred in case of acidemia less than 7.00.