Glue-sniffing and distal renal tubular acidosis: sticking to the facts

The Experience of Using Urinary Liver-Type Fatty Acid-Binding Protein for Follow-Up of Toluene Poisoning: A Case Report

Toluene poisoning is diagnosed based on toluene exposure history and the level of hippuric acid in the urine. Regular blood and urine tests are performed for follow-up. A 54-year-old man collided with a utility pole while driving a car and was rushed to our hospital with a complaint of loss of consciousness. Although the trauma was minor, toluene poisoning was suspected based on the presence of impaired consciousness, occupation is a painting job that involves toluene, and the presence of metabolic acidosis of the normal anion gap. Urinary hippuric acid and urinary liver-type fatty acid-binding protein (L-FABP) were measured, and a diagnosis of renal tubular acidosis (RTA) due to toluene toxicity was made. Urinary L-FABP levels decreased as the condition improved. Urinary L-FABP is a practical and rapid diagnostic and follow-up tool for toluene-induced RTA, and it is helpful to measure it in addition to conventional methods.

Arterial Blood Gases and Acid-Base Regulation

Disorders of acid-base status are common in the critically ill and prompt recognition is central to clinical decision making. The bicarbonate/carbon dioxide buffer system plays a pivotal role in maintaining acid-base homeostasis, and measurements of pH, PCO2, and HCO3 - are routinely used in the estimation of metabolic and respiratory disturbance severity. Hypoventilation and hyperventilation cause primary respiratory acidosis and primary respiratory alkalosis, respectively. Metabolic acidosis and metabolic alkalosis have numerous origins, that include alterations in acid or base intake, body fluid losses, abnormalities of intermediary metabolism, and renal, hepatic, and gastrointestinal dysfunction. The concept of the anion gap is used to categorize metabolic acidoses, and urine chloride excretion helps define metabolic alkaloses. Both the lungs and kidneys employ compensatory mechanisms to minimize changes in pH caused by various physiologic and disease disturbances. Treatment of acid-base disorders should focus primarily on correcting the underlying cause and the hemodynamic and electrolyte derangements that ensue. Specific therapies under certain conditions include renal replacement therapy, mechanical ventilation, respiratory stimulants or depressants, and inhibition of specific enzymes in intermediary metabolism disorders.

The pathophysiology of distal renal tubular acidosis

The kidneys have a central role in the control of acid-base homeostasis owing to bicarbonate reabsorption and production of ammonia and ammonium in the proximal tubule and active acid secretion along the collecting duct. Impaired acid excretion by the collecting duct system causes distal renal tubular acidosis (dRTA), which is characterized by the failure to acidify urine below pH 5.5. This defect originates from reduced function of acid-secretory type A intercalated cells. Inherited forms of dRTA are caused by variants in SLC4A1, ATP6V1B1, ATP6V0A4, FOXI1, WDR72 and probably in other genes that are yet to be discovered. Inheritance of dRTA follows autosomal-dominant and -recessive patterns. Acquired forms of dRTA are caused by various types of autoimmune diseases or adverse effects of some drugs. Incomplete dRTA is frequently found in patients with and without kidney stone disease. These patients fail to appropriately acidify their urine when challenged, suggesting that incomplete dRTA may represent an intermediate state in the spectrum of the ability to excrete acids. Unrecognized or insufficiently treated dRTA can cause rickets and failure to thrive in children, osteomalacia in adults, nephrolithiasis and nephrocalcinosis. Electrolyte disorders are also often present and poorly controlled dRTA can increase the risk of developing chronic kidney disease.

Beyond the Urine Anion Gap: In Support of the Direct Measurement of Urinary Ammonium

Ammonium is a major urinary buffer that is necessary for the normal excretion of the daily acid load. Its urinary rate of excretion (UNH₄) may be increased several fold in the presence of extrarenal metabolic acidosis. Therefore, measurement of UNH₄ can provide important clues about causes of metabolic acidosis. Because UNH₄ is not commonly measured in clinical laboratories, the urinary anion gap (UAG) was proposed as its surrogate about 4 decades ago, and it is still frequently used for that purpose. Several published studies strongly suggest that UAG is not a good index of UNH₄ and support the concept that direct measurement of UNH₄ is an important parameter to define in clinical nephrology. Low UNH₄ levels have recently been found to be associated with a higher risk of metabolic acidosis, loss of kidney function, and death in persons with chronic kidney disease, while surrogates like the UAG do not recapitulate this risk. In order to advance the field it is necessary for the medical community to become more familiar with UNH₄ levels in a variety of clinical settings. Herein, we review the literature, searching for available data on UNH₄ under normal and various pathological conditions, in an attempt to establish reference values to interpret UNH₄ results if and when UNH₄ measurements become available as a routine clinical test. In addition, we present original data in 2 large populations that provide further evidence that the UAG is not a good predictor of UNH₄. Measurement of urine NH₄ holds promise to aid clinicians in the care of patients, and we encourage further research to determine its best diagnostic usage.

Review of Clinical Disorders Causing Metabolic Acidosis

The various mechanisms responsible for the development of metabolic acidosis are briefly reviewed, and the metabolic acidoses are categorized both by mechanism and by the presence or absence of an increased anion gap. When a diagnosis of metabolic acidosis is established, it becomes imperative to identify the primary causative etiology as quickly as possible. This is often readily apparent from the history and physical exam (ie, diabetic ketoacidosis when the glucose is very high in a patient with diabetes mellitus; lactic acidosis in a patient with sepsis and hypotension, etc.). However, when the etiology is not obvious, it is very helpful to determine if the metabolic acidosis is of the hyperchloremic or high-anion-gap type (or a combination of both). Once this categorization has been established, a stepwise consideration of each of the potential causative etiologies will usually direct the clinician to order the appropriate diagnostic studies.

Paint-thinner-induced Acute Kidney Injury: A Case Series and Review

Occupational health hazards contribute significantly to the morbidity and mortality of workers in factories. Toluene has become a widely abused inhaled volatile drug. The spectrum of toluene-induced renal injury includes rhabdomyolysis, myoglobinemia, distal renal tubular acidosis (RTA), acute tubular necrosis, glomerulonephritis, and interstitial nephritis. We describe two patients with paint-thinner-induced kidney injury who were affected through different routes of exposure and recovered well, with one requiring dialysis support; the second patient, who had developed Type 1 distal RTA and mild kidney injury, was managed with conservative measures. Toluene can cause acute neurological symptoms, accompanied by severe metabolic alterations, as well as organ injury and dysfunction. A common association of the development of hypokalemic paralysis and metabolic acidosis with toluene intoxication was observed. Liver injury and rhabdomyolysis are also common. Vomiting, dehydration, tubular injury, and rhabdomyolysis are all possible additional causes of acute renal failure in toluene intoxication. Type 1 distal RTA, which is characterized by an inability to lower urine pH despite acidemia, results in hyperchloremic metabolic acidosis with hypokalemia. The management of acute toluene toxicity is largely conservative, consisting of correcting the electrolytes and the acid-base balance, fluid alterations, and renal replacement therapy in severe acute kidney injury. A clinical suspicion of organ failure and prompt supportive care leads to encouraging results. Adequate protective steps for workplaces involved in the use of such substances in confined spaces include prior risk assessment, using low-toxicity chemical products, ensuring adequate ventilation, safety training, and using appropriate personal protective equipment.

Evaluation of urinary acidification in children: Clinical utility

The kidney plays a fundamental role in acid-base homeostasis by reabsorbing the filtered bicarbonate and by generating new bicarbonate, to replace that consumed in the buffering of non-volatile acids, a process that leads to the acidification of urine and the excretion of ammonium (NH₄ ⁺). Therefore, urine pH (UpH) and urinary NH₄ ⁺ (UNH₄ ⁺) are valuable parameters to assess urinary acidification. The adaptation of automated plasma NH₄ ⁺ quantification methods to measure UNH₄ ⁺ has proven to be an accurate and feasible technique, with diverse potential indications in clinical practice. Recently, reference values for spot urine NH₄ ⁺/creatinine ratio in children have been published. UpH and UNH₄ ⁺, aside from their classical application in the study of metabolic acidosis, have shown to be useful in the identification of incomplete distal renal tubular acidosis (dRTA), an acidification disorder, without overt metabolic acidosis, extensively described in adults, and barely known in children, in whom it has been found to be associated to hypocitraturia, congenital kidney abnormalities and growth impairment. In addition, a low UNH₄ ⁺ in chronic kidney disease (CKD) is a risk factor for glomerular filtration decay and mortality in adults, even in the absence of overt metabolic acidosis. We here emphasize on the need of measuring UpH and UNH₄ ⁺ in pediatric population, establishing reference values, as well as exploring their application in metabolic acidosis, CKD and disorders associated with incomplete dRTA, including growth retardation of unknown cause.

Adsorption of Toluene and Water over Cationic-Exchanged Y Zeolites: A DFT Exploration

In this study, density functional theory (DFT) calculations have been performed to investigate the adsorption mechanisms of toluene and water onto various cationic forms of Y zeolite (LiY, NaY, KY, CsY, CuY and AgY). Our computational investigation revealed that toluene is mainly adsorbed via π-interactions on alkalis exchanged Y zeolites, where the adsorbed toluene moiety interacts with a single cation for all cases with the exception of CsY, where two cations can simultaneously contribute to the adsorption of the toluene, hence leading to the highest interaction observed among the series. Furthermore, we find that the interaction energies of toluene increase while moving down in the alkaline series where interaction energies are 87.8, 105.5, 97.8, and 114.4 kJ/mol for LiY, NaY, KY and CsY, respectively. For zeolites based on transition metals (CuY and AgY), our calculations reveal a different adsorption mode where only one cation interacts with toluene through two carbon atoms of the aromatic ring with interaction energies of 147.0 and 131.5 kJ/mol for CuY and AgY, respectively. More importantly, we show that water presents no inhibitory effect on the adsorption of toluene, where interaction energies of this latter were 10 kJ/mol (LiY) to 47 kJ/mol (CsY) higher than those of water. Our results point out that LiY would be less efficient for the toluene/water separation while CuY, AgY and CsY would be the ideal candidates for this application.

Inhalants

Toxic inhalants include various xenobiotics. Irritants cause upper and lower respiratory tract injuries. Highly water-soluble agents injure the upper respiratory tract, while low water-soluble inhalants injure the lower track. Asphyxiants are divided into simple asphyxiants and chemical asphyxiants. Simple asphyxiants displace oxygen, causing hypoxia, while chemical asphyxiants also impair the body's ability to use oxygen. Cyanide is a classic chemical asphyxiant. Treatment includes hydroxocobalamin. Electronic cigarette or vaping use-associated lung injury (EVALI) is a relatively new illness. Patients present with respiratory symptoms and gastrointestinal distress. EVALI appears to be associated with vaping cannabinoids. Treatment is supportive and may include steroids.

Use of Urine Electrolytes and Urine Osmolality in the Clinical Diagnosis of Fluid, Electrolytes, and Acid-Base Disorders

We discuss the use of urine electrolytes and urine osmolality in the clinical diagnosis of patients with fluid, electrolytes, and acid-base disorders, emphasizing their physiological basis, their utility, and the caveats and limitations in their use. While our focus is on information obtained from measurements in the urine, clinical diagnosis in these patients must integrate information obtained from the history, the physical examination, and other laboratory data.

Toluene Toxicity: A Case Report of Transdermal Exposure Causing Hypokalemic Paralysis

Rationale:

Hypokalemia is a common finding. Typically asymptomatic presentations of neuromuscular weakness emerge at levels below 2.5 mmol/L. Causes include gastrointestinal losses, renal losses, or intracellular shift, with gastrointestinal losses and diuretics accounting for the majority. Although the cause is often apparent on clinical assessment, a systematic approach incorporating urine biochemistry can aid in narrowing the differential in obscure cases.

Presentation:

We describe a case of a previously healthy 27-year-old man who presented with acute ascending paralysis, with an associated severe hypokalemia and metabolic acidosis. There were no apparent causes on clinical assessment.

Diagnosis:

Based on analysis of urine biochemistry, we concluded that a pathologic kaluresis was present, and given his acidemia and transient pathology, we diagnosed the patient with hypokalemic paralysis secondary to toluene toxicity.

Interventions:

We provided supportive care and electrolyte repletion for our patient; no specific therapies for toluene were required. Our patient was counseled regarding appropriate protective measures when handling toluene.

Outcomes:

Complete neurologic recovery and biochemical normalization occurred within 48 hours of presentation with supportive care. He continued to use proper precautions when handling toluene, and experienced no symptom relapse, or further abnormalities on both blood and urine chemistry.

Lessons learned:

Using this case, we review an algorithmic approach incorporating urine biochemistries to aid in the workup of hypokalemia. We review toluene as a toxicologic entity and highlight its role as a cause of hypokalemia.

The Use of Selected Urine Chemistries in the Diagnosis of Kidney Disorders

Urinary chemistries vary widely in both health and disease and are affected by diet, volume status, medications, and disease states. When properly examined, these tests provide important insight into the mechanism and therapy of various clinical disorders that are first detected by abnormalities in plasma chemistries. These tests cannot be interpreted in isolation, but instead require knowledge of key clinical information, such as medications, physical examination, and plasma chemistries, to include kidney function. When used appropriately and with knowledge of limitations, urine chemistries can provide important insight into the pathophysiology and treatment of a wide variety of disorders.

Hypokalemic Distal Renal Tubular Acidosis

Distal renal tubular acidosis (DRTA) is defined as hyperchloremic, non-anion gap metabolic acidosis with impaired urinary acid excretion in the presence of a normal or moderately reduced glomerular filtration rate. Failure in urinary acid excretion results from reduced H⁺ secretion by intercalated cells in the distal nephron. This results in decreased excretion of NH₄⁺ and other acids collectively referred as titratable acids while urine pH is typically above 5.5 in the face of systemic acidosis. The clinical phenotype in patients with DRTA is characterized by stunted growth with bone abnormalities in children as well as nephrocalcinosis and nephrolithiasis that develop as the consequence of hypercalciuria, hypocitraturia, and relatively alkaline urine. Hypokalemia is a striking finding that accounts for muscle weakness and requires continued treatment together with alkali-based therapies. This review will focus on the mechanisms responsible for impaired acid excretion and urinary potassium wastage, the clinical features, and diagnostic approaches of hypokalemic DRTA, both inherited and acquired.

Pseudo-Renal Tubular Acidosis: Conditions Mimicking Renal Tubular Acidosis

Hyperchloremic metabolic acidosis, particularly renal tubular acidosis, can pose diagnostic challenges. The laboratory phenotype of a low total carbon dioxide content, normal anion gap, and hyperchloremia may be misconstrued as hypobicarbonatemia from renal tubular acidosis. Several disorders can mimic renal tubular acidosis, and these must be appropriately diagnosed to prevent inadvertent and inappropriate application of alkali therapy. Key physiologic principles and limitations in the assessment of renal acid handling that can pose diagnostic challenges are enumerated.

Cerebellar infarction following accidental inhalation of toluene-mixed paint

We report a case of atypical cerebellar infarction following accidental inhalation of toluene mixed paint. An unconscious 57-year-old housewife with hypertension arrived at our emergency department by ambulance. She had been rescued from a basement (30 m³) 12 h after exposure to paint containing toluene (34%). On arrival, she was comatose (E₁V₁M₁) with a mild fever (37.4 °C). Physical examination showed chemical burns on her buttocks and rales on the left lung. Initial arterial blood gas with 15 L/min of oxygen showed a pH of 7.142, PCO₂ of 47.3 mmHg, and PaO₂ of 204.7 mmHg. She received endotracheal intubation and mechanical ventilation. Laboratory tests showed elevated white blood cells (26.86 × 10⁹/L), C-reactive protein (0.18 mg/dL), glucose (238 mg/Dl), and CPK (1389 U/L). At 5.5 h after arrival, she became responsive to verbal commands. On day 3, after removal of the endotracheal tube, she began to complain of an occipital headache without neurologic abnormalities. Brain magnetic resonance angiography (MRA) performed on day 6 showed a tiny acute infarction on the right cerebellar hemisphere. We serially measured urinary hippuric acid concentrations (reference range, ≤2.5 g/g creatinine) from 74 h (3.88) after hospital arrival to 218 h (0.5). She was discharged on day 14. Herein we presented a near fatal toluene intoxication (>45,000 mg/m³ estimated based on the basement volume and quantity of paint used) with atypical cerebellar infarction, compared with prior findings of bilateral involvement or reversibility.

Expanding the differential: toluene-induced toxicity

A 31-year-old woman presented to the hospital with generalised weakness and lower back and abdominal pain. The only significant finding on physical examination was the weakness of the legs. Laboratory analysis in the emergency department revealed that she was hypokalaemic with metabolic acidosis. She was treated with oral and intravenous potassium, which resolved her weakness. During the search for an explanation for her renal tubular acidosis, she said she was exposed to paint exposure while working on a friend's house. She was discharged on correction of her hypokalaemia, and a subsequent test revealed elevated blood toluene level.

Successful Management of Refractory Type 1 Renal Tubular Acidosis with Amiloride

A 28-year-old female with history of hypothyroidism, Sjögren's Syndrome, and Systemic Lupus Erythematosus (SLE) presented with complaints of severe generalized weakness, muscle pain, nausea, vomiting, and anorexia. Physical examination was unremarkable. Laboratory test showed hypokalemia at 1.6 mmol/l, nonanion metabolic acidosis with HCO₃ of 11 mmol/l, random urine pH of 7.0, and urine anion gap of 8 mmol/l. CT scan of the abdomen revealed bilateral nephrocalcinosis. A diagnosis of type 1 RTA likely secondary to Sjögren's Syndrome was made. She was started on citric acid potassium citrate with escalating dosages to a maximum dose of 60 mEq daily and potassium chloride over 5 years without significant improvement in serum K⁺ and HCO₃ levels. She had multiple emergency room visits for persistent muscle pain, generalized weakness, and cardiac arrhythmias. Citric acid potassium citrate was then replaced with sodium bicarbonate at 15.5 mEq every 6 hours which was continued for 2 years without significant improvement in her symptoms and electrolytes. Amiloride 5 mg daily was added to her regimen as a potassium sparing treatment with dramatic improvement in her symptoms and electrolyte levels (as shown in the figures). Amiloride was increased to 10 mg daily and potassium supplementation was discontinued without affecting her electrolytes. Her sodium bicarbonate was weaned to 7.7 mEq daily.

A case of reversible cardiomyopathy associated with acute toluene exposure

Inhalation of toluene-based products is popular among young adults. It has been shown to have a variety of adverse effects on several organs and systems. Although the heart seems to be a sensitive target organ to toluene, cardiotoxicity has often been ignored, especially in cases of acute toluene abuse, with relatively low concentrations. Thereby, routine cardiac examination and echocardiography for cardiotoxicity should be performed in cases of acute toluene exposure, even though there is no cardiovascular sign or symptoms.

Osmotic Pressure in Clinical Medicine with an Emphasis on Dialysis

Since the beginning of life of the first multicellular organisms, the preservation of a physiologic milieu for every cell in the organism has been a critical requirement. A particular range of osmolality of the body fluids is essential for the maintenance of cell volume. In humans the stability of electrolyte concentrations and their resulting osmolality in the body fluids is the consequence of complex interactions between cell membrane functions, hormonal control, thirst, and controlled kidney excretion of fluid and solutes. Knowledge of these mechanisms, of the biochemical principles of osmolality, and of the relevant situations occurring in disease is of importance to every physician. This comprehensive review summarizes the major facts on osmolality, its relation to electrolytes and other solutes, and its relevance in physiology and in disease states with a focus on dialysis-related considerations.

Scintigraphic evaluation of renal functional damage in volatile substance abusers

OBJECTIVE

Volatile organic compounds can be maintained easily and can cause dependency. Volatile substance abuse may cause damage by affecting several systems. The aim of our study was to evaluate renal functional damage in volatile substance abusers by diuretic renogram.

METHODS

Twenty nine volatile substance abusers and 30 young healthy voluntary young men were included in our study. Technetium-99m mertiatide diuretic renogram was used to evaluate renal functions and collective system urodynamics to investigate the progress of renal functional damage. Images were evaluated visually and quantitatively. Split renal function of each kidney, time to peak activity (Tmax), and half-time for radiopharmaceutical clearance from pelvicalyceal system (T1/2), ratio of cortical and whole-kidney counts at 20-3 min, and maximum counts (T20/3 and T20/max) were compared in the two groups.

RESULTS

In the study group, time to reach peak activity was statistically prolonged compared with the healthy volunteers. In the volatile substance abuser group, the average Tmax values, average T1/2 values, cortical and whole-kidney T20/3, and T20/max values were found to be prolonged compared with the control group in the diuretic renogram. There was no significant difference in the split renal function ratios between the two groups.

CONCLUSION

In this study, possible renal functional damage was evaluated in volatile substance abusers by diuretic renogram. In conclusion, diuretic renogram can be useful in the evaluation of renal functional damage before blood renal function tests are affected and it could be used in the follow-up of the disease in volatile substance abusers. The results of this pilot study from our country, of course, should be supported by further clinical studies.

Psychiatric and anesthetic implications of substance abuse: Present scenario

Substance abuse has crossed all social, economic, and geographic borders and is spreading its fangs in each and every sphere of society irrespective of age, gender, caste, creed, and religion. These days, we encounter several patients of substance dependence who visit different hospitals for elective surgical procedures or in emergency (e.g., roadside accidents and with various complications associated with substance abuse). These patients at that time may be either addicted to them or are intoxicated by them or on de addiction treatment. Acute or chronic use of these drugs affect the respiratory, cardiovascular, central nervous, renal, hematological, and hepatic system variably in individuals thus due to diverse clinical presentations a complete understanding of the path physiology and anesthetic implications of drug abuse is essential to tailor a safe anesthetic plan for these high-risk group of patients.

Drug-Induced Metabolic Acidosis

Metabolic acidosis could emerge from diseases disrupting acid-base equilibrium or from drugs that induce similar derangements. Occurrences are usually accompanied by comorbid conditions of drug-induced metabolic acidosis, and clinical outcomes may range from mild to fatal. It is imperative that clinicians not only are fully aware of the list of drugs that may lead to metabolic acidosis but also understand the underlying pathogenic mechanisms. In this review, we categorized drug-induced metabolic acidosis in terms of pathophysiological mechanisms, as well as individual drugs’ characteristics.

Chronic intermittent toluene inhalation in adolescent rats results in metabolic dysfunction with altered glucose homeostasis

BACKGROUND AND PURPOSE

Abuse of toluene-containing inhalants is an increasing public health problem, especially among adolescents. Abuse during adolescence is associated with emaciation, while industrial exposure leads to altered glycaemic control suggesting metabolic instability. However, the relationship between adolescent inhalant abuse and metabolic dysfunction remains unknown.

EXPERIMENTAL APPROACH

To model human abuse patterns, we exposed male adolescent Wistar rats [postnatal day (PND) 27] to chronic intermittent inhaled toluene (CIT, 10,000 ppm) or air (control) for 1 h·day(-1) , three times a week for 4 weeks. Feeding and body composition were monitored. After 4 weeks, circulating metabolic hormone concentrations and responses to a glucose tolerance test (GTT) were measured. Dietary preference was measured by giving animals access to either a 'western diet' plus standard chow (WC + SC) or standard chow alone during 4 weeks of abstinence. Metabolic hormones and GTT were subsequently measured.

KEY RESULTS

Adolescent CIT exposure significantly retarded weight gain, altered body composition, circulating metabolic hormones and responses to a GTT. While reduced body weight persisted, responses to a GTT and circulating hormones appeared to normalize for animals on standard chow following abstinence. In CIT-exposed WC + SC rats, we observed impaired glucose tolerance associated with altered metabolic hormones. Analysis of hypothalamic genes revealed differential expression profiles in CIT-exposed rats following both the exposure period and abstinence, suggesting a central contribution to inhalant-induced metabolic dysfunction.

CONCLUSION AND IMPLICATIONS

CIT exposure during adolescence has long-term effects on metabolic function, which may increase the risk of disorders related to energy balance and glycaemic control.

Acute toluene intoxication--clinical presentation, management and prognosis: a prospective observational study

Background

Toluene is one of the most widely abused inhaled drugs due to its acute neurologic effects including euphoria and subsequent depression. However, dangerous metabolic abnormalities are associated to acute toluene intoxication. It has been previously reported that rhabdomyolysis and acute hepatorenal injury could be hallmarks of the condition, and could constitute risk factors for poor outcomes. The objective was to describe the clinical presentation, to characterize the renal and liver abnormalities, the management and prognosis associated to acute toluene intoxication.

Methods

We prospectively assessed 20 patients that were admitted to a single center’s emergency department from September 2012 to June 2014 with clinical and metabolic alterations due to acute toluene intoxication.

Results

The main clinical presentation consisted of weakness associated to severe hypokalemia and acidosis. Renal glomerular injury (proteinuria) is ubiquitous. Biliary tract injury (alkaline phosphatase and gamma-glutamyl transpeptidase elevations) disproportional to hepatocellular injury is common. Rhabdomyolysis occurred in 80 % of patients, probably due to hypokalemia and hypophosphatemia. There were three deaths, all female, and all associated with altered mental status, severe acidosis, hypokalemia and acute oliguric renal failure. The cause of death was in all cases due to cardiac rhythm abnormalities.

Conclusion

The hallmarks of acute toluene intoxication are hypokalemic paralysis and metabolic acidosis. Liver injury and rhabdomyolysis are common. On admission, altered mental status, renal failure, severe acidemia and female gender (not significant in our study, but present in all three deaths) could be associated with a poor outcome, and patients with these characteristics should be considered to be treated in an intensive care unit.

Renal tubular acidosis is highly prevalent in critically ill patients

Introduction

Hyperchloremic acidosis is frequent in critically ill patients. Renal tubular acidosis (RTA) may contribute to acidemia in the state of hyperchloremic acidosis, but the prevalence of RTA has never been studied in critically ill patients. Therefore, we aimed to investigate the prevalence, type, and possible risk factors of RTA in critically ill patients using a physical-chemical approach.

Methods

This prospective, observational trial was conducted in a medical ICU of a university hospital. One hundred consecutive critically ill patients at the age ≥18, expected to stay in the ICU for ≥24 h, with the clinical necessity for a urinary catheter and the absence of anuria were included.

Base excess (BE) subset calculation based on a physical-chemical approach on the first 7 days after ICU admission was used to compare the effects of free water, chloride, albumin, and unmeasured anions on the standard base excess. Calculation of the urine osmolal gap (UOG) - as an approximate measure of the unmeasured urine cation NH₄⁺ - served as determinate between renal and extrarenal bicarbonate loss in the state of hyperchloremic acidosis.

Results

During the first week of ICU stay 43 of the patients presented with hyperchloremic acidosis on one or more days represented as pronounced negative BE_Chloride. In 31 patients hyperchloremic acidosis was associated with RTA characterized by a UOG ≤150 mosmol/kg in combination with preserved renal function. However, in 26 of the 31 patients with RTA metabolic acidosis was neutralized by other acid-base disturbances leading to a normal arterial pH.

Conclusions

RTA is highly prevalent in critically ill patients with hyperchloremic acidosis, whereas it is often neutralized by the simultaneous occurrence of other acid-base disturbances.

Trial registration

Clinicaltrials.gov NCT02392091. Registered 17 March 2015

Etiologic and therapeutic analysis in patients with hypokalemic nonperiodic paralysis

BACKGROUND

Hypokalemic nonperiodic paralysis represents a group of heterogeneous disorders with a large potassium (K(+)) deficit. Rapid diagnosis of curable causes with appropriate treatment is challenging to avoid the sequelae of hypokalemia. We prospectively analyzed the etiologies and therapeutic characteristics of hypokalemic nonperiodic paralysis.

METHODS

Over an 8-year period, patients with hypokalemic nonperiodic paralysis were enrolled by excluding those with hypokalemic periodic paralysis due to acute shift of K(+) into cells. Blood and spot urine samples were collected for the measurements of electrolytes, pH, and biochemistries. Intravenous potassium chloride (KCl) at a rate of 10-20 mmol/h was administered until muscle strength recovered.

RESULTS

We had identified 58 patients with hypokalemic nonperiodic paralysis from 208 consecutive patients with hypokalemic paralysis, and their average K(+) concentration was 1.8 ± 0.2 mmol/L. Among patients with low urinary K(+) excretion (n = 17), chronic alcoholism, remote diuretic use, and anorexia/bulimia nervosa were the most common causes. Among patients with high urinary K(+) excretion (n = 41) and metabolic acidosis, renal tubular acidosis and chronic toluene abuse were the main causes, while primary aldosteronism, Gitelman syndrome, and diuretics were the leading diagnoses with metabolic alkalosis. The average KCl dose needed to restore muscle strength was 3.8 ± 0.8 mmol/kg. Initial lower plasma K(+), volume depletion, and high urinary K(+) excretion were associated with higher recovery KCl dosage. During therapy, patients with paradoxical hypokalemia (n = 32) who required more KCl supplementation than patients without (4.1 ± 0.7 vs 3.4 ± 0.7 mmol/kg, P < 0.001) often exhibited significantly higher plasma renin activity and received a higher volume of normal saline before its appearance.

CONCLUSIONS

Understanding the common etiologies of hypokalemic nonperiodic paralysis may aid in early diagnosis. Patients with initial lower plasma K(+), renal K(+) wasting, and hypovolemia required higher recovery K(+) dosage. Paradoxical hypokalemia is prone to develop in hypovolemic patients even during K(+) supplementation with volume repletion.

American Society of Nephrology quiz and questionnaire 2014: acid-base and electrolyte disorders

The Nephrology Quiz and Questionnaire remains an extremely popular session for attendees of the Annual Kidney Week Meeting of the American Society of Nephrology. Once again, in 2014 the conference hall was overflowing with audience members and eager quiz participants. Topics covered by the expert discussants included electrolyte and acid-base disorders, glomerular disease, ESRD/dialysis, and transplantation. Complex cases from each of these categories along with single-best-answer questions were prepared and submitted by the panel of experts. Before the meeting, program directors of United States nephrology training programs and nephrology fellows answered the questions using an Internet-based questionnaire. During the live session, members of the audience tested their knowledge and judgment on a series of case-oriented questions prepared and discussed by the experts. They compared their answers in real time using audience response devices with the answers of the nephrology fellows and training program directors. The correct and incorrect answers were then discussed after the audience responses and the results of the questionnaire were displayed. As always, the audience, lecturers, and moderators enjoyed this educational session. This article recapitulates the acid-base and electrolyte disorders portion of the session and reproduces its educational value for the readers of the Clinical Journal of the American Society of Nephrology. Enjoy the clinical cases and expert discussions.

Clinical and biochemical analysis of acute paint thinner intoxication in adults: a retrospective descriptive study

CONTEXT

Paint thinner contains a mixture of various aromatic hydrocarbons. A few studies have reported biochemical abnormalities and clinical symptoms of paint thinner intoxication among adult patients.

OBJECTIVE

We aimed to design a retrospective descriptive study to evaluate clinical and laboratory biochemistry abnormalities due to paint thinner intoxication among adult patients.

METHODS

Data were obtained by using questionnaires from paint thinner-intoxicated patients recruited at the Loghman-Hakim General Teaching Hospital Poison Center.

RESULTS

Clinical and paraclinical data from a total of 37 patients, 24 males (64.86%) and 13 females (35.14%) with the mean age of 34.35 ± 14.15 years and mode of 22 years, was obtained and analyzed. Patients' ages ranged between 15 and 70 years. The estimated mean consumed dose was 246.70 ± 390.72 ml with a mode of 60 ml (range of 1-1500 ml). Nausea, vomiting, asthma, sore throat, stomach ache, drowsiness, dizziness, agitation, cough and diarrhea were the most frequent clinical features, respectively. Reported tissue damage biomarkers were alkaline phosphatase (ALP, 233.84 ± 122.06) and lactate dehydrogenase enzymes (LDH, 749.33 ± 471.03 IU/l). They reflected development of liver and pulmonary toxicities. Arterial blood gas (ABG) showed acidosis without hypoxia in adult paint thinner-intoxicated patients.

DISCUSSION AND CONCLUSION

Focusing on biochemical abnormalities and clinical toxicity symptoms is essential for screening organs in paint thinner toxicity. In addition, they provide good information for physicians/clinical toxicologists to perform appropriate conservative treatments in adult paint thinner-intoxicated patients.

The importance of the ionic product for water to understand the physiology of the acid-base balance in humans

Human plasma is an aqueous solution that has to abide by chemical rules such as the principle of electrical neutrality and the constancy of the ionic product for water. These rules define the acid-base balance in the human body. According to the electroneutrality principle, plasma has to be electrically neutral and the sum of its cations equals the sum of its anions. In addition, the ionic product for water has to be constant. Therefore, the plasma concentration of hydrogen ions depends on the plasma ionic composition. Variations in the concentration of plasma ions that alter the relative proportion of anions and cations predictably lead to a change in the plasma concentration of hydrogen ions by driving adaptive adjustments in water ionization that allow plasma electroneutrality while maintaining constant the ionic product for water. The accumulation of plasma anions out of proportion of cations induces an electrical imbalance compensated by a fall of hydroxide ions that brings about a rise in hydrogen ions (acidosis). By contrast, the deficiency of chloride relative to sodium generates plasma alkalosis by increasing hydroxide ions. The adjustment of plasma bicarbonate concentration to these changes is an important compensatory mechanism that protects plasma pH from severe deviations.

American Society of Nephrology Quiz and Questionnaire 2013: electrolyte and acid-base

The Nephrology Quiz and Questionnaire (NQ&Q) remains an extremely popular session for attendees of the annual meeting of the American Society of Nephrology. As in past years, the conference hall was overflowing with interested audience members. Topics covered by expert discussants included electrolyte and acid-base disorders, glomerular disease, ESRD/dialysis, and transplantation. Complex cases representing each of these categories along with single-best-answer questions were prepared by a panel of experts. Prior to the meeting, program directors of United States nephrology training programs answered questions through an Internet-based questionnaire. A new addition to the NQ&Q was participation in the questionnaire by nephrology fellows. To review the process, members of the audience test their knowledge and judgment on a series of case-oriented questions prepared and discussed by experts. Their answers are compared in real time using audience response devices with the answers of nephrology fellows and training program directors. The correct and incorrect answers are then briefly discussed after the audience responses, and the results of the questionnaire are displayed. This article recapitulates the session and reproduces its educational value for the readers of CJASN. Enjoy the clinical cases and expert discussions.

Metabolic acidosis in toluene sniffing

Toluene sniffing, frequently described under the generic category of "glue sniffing," is a potential cause of normal anion gap metabolic acidosis due to distal renal tubular acidosis. Urine anion gap is used to diagnose metabolic acidosis of a normal anion gap variety; however, pitfalls exist when using urine anion gap in the setting of toluene sniffing. We present the case of a young woman who had a normal anion gap metabolic acidosis due to toluene sniffing and an unexpectedly low urine anion gap. In such a scenario, the urine anion gap will underestimate the rate of ammonia excretion when the conjugate bases of acids other than HCl are excreted in large quantities. Estimation of the urine osmolal gap will provide a more accurate ammonia excretion rate in these circumstances. The challenges in interpretation of the urine anion gap and ammonia excretion in the setting of distal renal tubular acidosis due to toluene toxicity are discussed.

Methanol and ethylene glycol intoxication

Accidental or intentional ingestion of substances containing methanol and ethylene glycol can result in death, and some survivors are left with blindness, renal dysfunction, and chronic brain injury. However, even in large ingestions, a favorable outcome is possible if the patient arrives at the hospital early enough and the poisoning is identified and appropriately treated in a timely manner. This review covers the common circumstances of exposure, the involved toxic mechanisms, and the clinical manifestations, laboratory findings, and treatment of methanol and ethylene glycol intoxication.

Direct urine ammonium measurement: time to discard urine anion and osmolar gaps

Background

A failure of urine ammonium to increase during acidosis indicates impaired renal acidification, and the urinary ammonium concentration is therefore a useful investigation in determining the cause of a metabolic acidosis. However, urine ammonium measurements are not widely available in routine diagnostic laboratories. This has led to the use of urine anion or osmolar gaps, which are unsatisfactory as surrogates for urine ammonium measurement.

Methods

We evaluated the adaptation of two widely available automated plasma ammonium assays for measurement of urinary ammonium.

Results

Both assays showed good recovery and linearity in urine samples spiked with ammonium chloride, and acceptable precision. Urine ammonium concentrations estimated from urinary anion and osmolar gaps showed poor agreement with measured urine ammonium concentrations.

Conclusions

Direct urine ammonium measurements are easily performed with modern autoanalysers by simple adaptation of routine plasma ammonium assays. The use of urine anion and osmolar gaps should be abandoned where direct measurement is available.

Differential diagnosis of nongap metabolic acidosis: value of a systematic approach

Nongap metabolic acidosis is a common form of both acute and chronic metabolic acidosis. Because derangements in renal acid-base regulation are a common cause of nongap metabolic acidosis, studies to evaluate renal acidification often serve as the mainstay of differential diagnosis. However, in many cases, information obtained from the history and physical examination, evaluation of the electrolyte pattern (to determine if a nongap acidosis alone or a combined nongap and high anion gap metabolic acidosis is present), and examination of the serum potassium concentration (to characterize the disorder as hyperkalemic or hypokalemic in nature) is sufficient to make a presumptive diagnosis without more sophisticated studies. If this information proves insufficient, indirect estimates or direct measurement of urinary NH(4)(+) concentration, measurement of urine pH, and assessment of urinary HCO(3)(-) excretion can help in establishing the diagnosis. This review summarizes current information concerning the pathophysiology of this electrolyte pattern and the value and limitations of all of the diagnostic studies available. It also provides a systematic and cost-effective approach to the differential diagnosis of nongap metabolic acidosis.

Toluene inducing acute respiratory failure in a spray paint sniffer

Background:

Toluene, formerly known as toluol, is an aromatic hydrocarbon that is widely used as an industrial feedstock and as a solvent. Like other solvents, toluene is sometimes also used as an inhalant drug for its intoxicating properties. It has potential to cause multiple effects in the body including death.

Case Report:

I report a case of a 27-year-old male, chronic spray paint sniffer, who presented with severe generalized muscle weakness and developed acute respiratory failure requiring ventilatory support. Toluene toxicity was confirmed with measurement of hippuric acid of 8.0 g/L (normal <5.0 g/L).

Conclusions:

Acute respiratory failure is a rare complication of chronic toluene exposure that may be lethal if it is not recognized immediately. To our knowledge, this is the second case of acute respiratory failure due to toluene exposure.

Distal renal tubular acidosis, hypokalemic paralysis, nephrocalcinosis, primary hypothyroidism, growth retardation, osteomalacia and osteoporosis leading to pathological fracture: a case report

Renal tubular acidosis (RTA) is a constellation of syndromes arising from different derangements of tubular acid transport. Recent advances in the biology of urinary acidification have allowed us to discern various molecular mechanisms responsible for these syndromes. RTA often presents as renal stone disease with nephrocalcinosis, ricket/osteomalacia and growth retardation in children with ultimate short stature in adulthood. The case reported here has features of distal renal tubular acidosis (dRTA), hypokalemic paralysis, primary hypothyroidism, growth retardation, osteomalacia and osteopenia leading to stress fracture. All these features presenting in a single case (as in our case) is a rare occurrence, so far other cases of distal renal tubular acidosis (dRTA) have been reported.

Atrioventricular conduction abnormality and hyperchloremic metabolic acidosis in toluene sniffing

Toluene is an aromatic hydrocarbon with widespread industrial use as an organic solvent. As a result of the euphoric effect and availability of these substances, inhalation of toluene-based products is popular among young adults and children. Chronic or acute exposure is known to cause acid-base and electrolyte disorders, and to be toxic to the nervous and hematopoietic systems. We report a 38-year-old man who suffered from general muscular weakness of all extremities after toluene sniffing, which was complicated with hypokalemic paralysis, atrioventricular conduction abnormality, and normal anion gap hyperchloremic metabolic acidosis. Renal function, serum potassium and acid-base status normalized within 3 days after aggressive potassium chloride and intravenous fluid replacement. Electrocardiography showed regression of first-degree atrioventricular block. Exposure to toluene can lead to cardiac arrhythmias and sudden sniffing death syndrome. Tachyarrhythmia is the classical manifestation of toluene cardiotoxicity. Atrioventricular conduction abnormalities have been rarely mentioned in the literature. Knowledge of the toxicology and medical complications associated with toluene sniffing is essential for clinical management of these patients.

Reported survival with severe mixed acidosis and hyperlactemia after toluene poisoning

Lactic acidosis is a recognized complication of the inhalant abuse such as toluene, especially in patients with renal insufficiency. We report a case of severe metabolic acidosis and hyperlactemia due to toluene sniffing. The favorable outcome, despite extremely poor clinical symptoms, signs, laboratory and radiological findings, was unexpected. Specific aspects of the clinical course are addressed. Toluene sniffing should be considered in evaluating sever metabolic acidosis. Favorable outcome could be achieved with early diagnosis and proper interventions.