Pseudo-Bartter syndrome as the initial presentation of cystic fibrosis in children: an important diagnosis not to be missed.

Pseudo-Bartter syndrome (PBS) is characterised by hyponatraemic, hypochloraemic metabolic alkalosis that mimics Bartter syndrome, without renal tubular disease. We present a case of an infant with a positive cystic fibrosis (CF) newborn screening, hospitalised during the summer with dehydration, oliguria and apathy. Blood analysis revealed hypochloraemic metabolic alkalosis, hypokalaemia and hyponatraemia. Urine analysis showed leucocyturia with reduced sodium and chloride excretion fraction, and urinary culture was positive for Citrobacter koseri After antibiotherapy and intravenous rehydration with additional supplementation of sodium and chloride, the patient recovered completely. PBS is one of CF complications that is especially prevalent in infants and young children with increased sweating and/or other causes of additional loss of sodium and chloride. Clinical awareness of this syndrome and its strong clinical suspicion are extremely important for an early diagnosis and treatment of CF, particularly in countries where the universal screening of CF is not routinely performed.

Severe Multifactorial Metabolic Alkalosis in the Emergency Department: A Case Report.

BACKGROUND: Metabolic alkalosis is an uncommon clinical entity resulting from a wide variety of underlying etiologies including gastrointestinal, renal, endocrine, and metabolic causes. It is a typically clinically silent condition; however, severe cases can be life-threatening, mandating both a systematic investigative approach and an early aggressive management strategy. CASE REPORT: We present a case of a 58-year-old man with severe, multifactorial metabolic alkalosis (pH 7.72, HCO3- 42 mmol/L, pCO2 31 mm Hg) resulting from refractory vomiting, severe hypokalemia (2.0 mmol/L), and hypoalbuminemia (albumin 20 g/L). WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Severe metabolic alkalosis is associated with significant morbidity and mortality. Clinicians need to be aware of the potential underlying causes in these cases, as well as how to delineate between chloride- and non-chloride-depleted states, which dictates initial treatment. We provide a pragmatic summary of the evaluation, pertinent investigations, and early management of these cases.

Severe Alkalemia and hypokalemia after chronic exposure to alkaline water.

Consumption of alkaline electrolyzed water (AEW) has become increasingly popular for consumer use. Although these alkaline water products are now commonly used, they are of questionable health benefit. Some individuals believe that it may help their dyspepsia. Furthermore, there is a paucity of evidence on its toxicologic profile and adverse effects. This is a single case report of a 42-year-old female with a past medical history of gestational diabetes, necrotizing pancreatitis, presented to the Emergency Department for 3 weeks of lethargy, weakness, difficulty walking, and vomiting. She endorsed consuming 5  liters (L) of alkaline water daily for the past month. Initial labs showed pH 7.69, potassium 1.6meQ/L, sodium 133 meQ/L, chloride 65 mmol/L, magnesium 0.9 meQ/L, and bicarbonate 46 mmol/L, and lactate of 13.2 mmol/L. EKG showed sinus tachycardia with QTc of 630 milliseconds. Patient was treated supportively with intravenous fluids and electrolyte replacement. The potassium rose to 6.6 meQ/L, which then the patient was treated for hyperkalemia. After four days of intravenous fluid and electrolyte replacement, the patient's electrolytes and acid-base status normalized, and she was transferred to the medical floors for further management. This case report illustrates severe metabolic alkalosis and hypokalemia in the setting of chronic alkaline water exposure. It also is an example of alkalemia with hyperlactatemia, or "lactic alkalosis". To our knowledge, there is no previous literature reporting serious adverse effects of alkaline bottled water products.

Metabolic Acid-Base Disorders.

Metabolic acid-base disturbances are frequently encountered in the emergency department, and many of these patients are critically ill. In the evaluation of patients with these maladies, it is important for the emergency clinician to determine the cause, which can usually be elicited from a thorough history and physical examination. There are several mnemonics that can be used to form an appropriate list of potential causes. Most of the time, the management of these patients requires no specific treatment of the acid-base status but, rather, requires treatment of the underlying disorder that is causing the acid-base disturbance.

Cystic fibrosis and CFTR-related disorder with electrolyte imbalance at diagnosis: clinical features and outcome in an Italian cohort.

There is limited information available on the clinical data, sweat test trends, and outcomes of individuals with cystic fibrosis (CF) who present with an isolated episode of hypoelectrolytemia with metabolic alkalosis (HMA). This study describes a cohort of Italian individuals with HMA as presenting symptom. The study is a retrospective multicenter analysis of individuals who presented with HMA as an initial symptom and was followed at 8 Italian CF Centers, from March 1988 to March 2022. Demographic, clinical, microbiological, biochemical, and genetic data were extracted from local health records. Ninety-three individuals were enrolled in the study. At first evaluation, 82 (88.2%) were diagnosed with CF, and 11 received a CFTR-Related Disorder (CFTR-RD) diagnostic label. Twenty-three (85.1%) out of the 27 subjects who underwent CF neonatal screening (NBS) resulted falsely negative. After a mean observational period of 11.5 years, most of subjects had a mild pulmonary phenotype, pancreatic sufficiency, and rarely CF-related complications. Four CFTR-RD changed to a CF diagnosis during the study period, resulting in 86 (92.4%) subjects classified as CF. CONCLUSIONS:  Most CF patients presenting with isolated HMA have a mild course of disease and rarely CF-related complications. WHAT IS KNOWN: • Isolated episode of hypoelectrolytemia with metabolic alkalosis is a well-known onset symptom of Cystic Fibrosis in infancy. • There is limited information available on the clinical data and outcomes of individuals with Cystic Fibrosis who present with electrolyte imbalance at diagnosis. WHAT IS NEW: • Most patients with Cystic Fibrosis presenting with isolated hypoelectrolytemia and metabolic alkalosis have a mild course of disease and rarely CF-related complications. • Electrolyte imbalance at diagnosis of Cystic Fibrosis is a common symptom in children not screened for CF at birth, or in those who received a false negative result from newborn screening.

Acid-base and electrolyte evaluation in dogs with upper GI obstruction: 115 dogs (2015-2021).

OBJECTIVES: Metabolic alkalosis, although uncommon in small animals, has been previously associated with gastrointestinal obstructions. Depending on the population and disease process evaluated, previous prevalence of metabolic alkalosis is reported as ranging from 2% to 45% in canine patients. The objective of this study was to determine the prevalence of metabolic alkalosis and other acid-base and electrolyte disorders in a cohort of dogs with a confirmed upper gastrointestinal obstruction. MATERIALS AND METHODS: Electronic medical records were reviewed to identify dogs who presented for vomiting with evidence of an upper gastrointestinal obstruction from January 2015 to October 2021. Patients were enrolled only if a preoperative venous blood gas was obtained and analysed in house. Traditional acid-base analysis was utilised to determine an acid-base status before relieving the obstruction. When available, post-operative venous acid-base status was determined within 24 hours after surgery, and compared to preoperative results. RESULTS: A total of 115 dogs were included in the study. Twenty-five out of 115 (22%) dogs displayed either a simple metabolic alkalosis or a mixed acid-base disturbance before surgery. Twenty-seven out of 115 dogs (37%) had a normal acid-base status at entry. Seventy-one dogs had pre- and post-operative venous blood gas results available. Metabolic alkalosis was resolved in nearly all patients post-operatively, with no patients displaying a simple metabolic alkalosis. A mixed metabolic acidosis and respiratory alkalosis was the most common condition post-operatively, found in 25 of 71 (35%) dogs. Severe derangements of electrolytes were infrequent preoperatively (3/115; 2.6%). A majority of patients in this study exhibited hypokalaemia (64.4%), hypochloraemia (72.8%) and hyponatraemia (77.4%) on preoperative venous blood gases. Venous pH, Pv CO2 , bicarbonate and base excess were significantly higher preoperatively when compared to the post-operative results. CLINICAL SIGNIFICANCE: This study found the prevalence of pre-operative metabolic alkalosis in dogs with a documented upper gastrointestinal obstruction to be lower than previously reported. Surgical or endoscopic alleviation of the upper gastrointestinal obstruction resulted in resolution of metabolic alkalosis in nearly all patients.

A Case of Milk-Alkali Syndrome Caused by Diuretic-Induced Alkalosis and Polypharmacy.

Milk-alkali syndrome, which is characterized by hypercalcemia, metabolic alkalosis, and renal dysfunction, typically results from the ingestion of large amounts of calcium and absorbable alkaline products. However, these symptoms can also manifest when alkalosis and calcium loading occur simultaneously, owing to other factors. We report a case of milk-alkali syndrome caused by loop-diuretic-induced alkaline load and polypharmacy in an 85-year-old Japanese woman with multiple comorbidities, including osteoporosis, hypertension, type 2 diabetes, dyslipidemia, and Parkinson's disease. The patient regularly took 14 drugs, including calcium L-aspartate, eldecalcitol, celecoxib, and a fixed-dose combination of losartan and hydrochlorothiazide. Immediately before admission, furosemide was administered for the treatment of edema. The patient presented with chest discomfort, general malaise, and clinical signs of dehydration, hypercalcemia, hypophosphatemia, hypokalemia, and hypomagnesemia, accompanied by electrocardiogram abnormalities, renal dysfunction, and chloride-resistant metabolic alkalosis. The hypercalcemia was specifically induced by calcium L-aspartate and eldecalcitol. The hypomagnesaemia and hypophosphatemia were caused by diuretics and hypercalcemia. Thus, all the oral medications were discontinued, and rehydration and electrolyte correction therapy were administered. The final diagnosis was milk-alkali syndrome caused by the concomitant use of loop diuretics and other medications, without absorbable alkaline preparation use. This case underscores the importance of considering drug-related factors, checking concomitant medications, and being aware of the benefits, harmful effects, and side effects of polypharmacy in older adults with multimorbidity.

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.

Respiratory Acidosis and Respiratory Alkalosis: Core Curriculum 2023.

The respiratory system plays an integral part in maintaining acid-base homeostasis. Normal ventilation participates in the maintenance of an open buffer system, allowing for excretion of CO2 produced from the interaction of nonvolatile acids and bicarbonate. Quantitatively of much greater importance is the excretion of CO2 derived from volatile acids produced from the complete oxidation of fat and carbohydrate. A primary increase in CO2 tension of body fluids is the cause of respiratory acidosis and develops most commonly from one or more of the following: (1) disorders affecting gas exchange across the pulmonary capillary, (2) disorders of the chest wall and the respiratory muscles, and/or (3) inhibition of the medullary respiratory center. Respiratory alkalosis or primary hypocapnia is most commonly caused by disorders that increase alveolar ventilation and is defined by an arterial partial pressure of CO2 <35 mm Hg with subsequent alkalization of body fluids. Both disorders can lead to life-threatening complications, making it of paramount importance for the clinician to have a thorough understanding of the cause and treatment of these acid-base disturbances.

Total colectomy for poorly controlled hypokalaemia due to Gitelman syndrome.

Gitelman syndrome (GS) is an autosomal recessive tubulopathy caused by dysfunction of the thiazide-sensitive sodium-chloride cotransporter, which leads to hypokalaemia, metabolic alkalosis, hypomagnesaemia and hypocalciuria. Patients with GS show varied clinical features due to hypokalaemia: tetany, muscle weakness, periodical paralysis and constipation, which is one of the most frequent ones. This paper presents the case of a woman in her 40s referred to our endocrinology department for severe hypokalaemia. After biochemical and genetic analyses, a diagnosis of GS was established. Concurrently, the patient suffered from refractory constipation due to hypokalaemia and underwent a total colectomy with ileorectal anastomosis, which cured both disorders without any medication for 3 years.

Acquired autoimmune Bartter syndrome in a patient with primary hypothyroidism.

We describe an unusual clinical presentation of autoimmune Bartter syndrome in a patient with primary hypothyroidism. A 65-year-old female patient was admitted with neuromuscular weakness associated with hypokalemia and metabolic alkalosis. She had a suboptimal response to potassium supplementation and potassium-sparing diuretic resulting in re-hospitalization with the same symptoms. A detailed serum and urinary biochemistry analysis in the absence of other causes of potassium wasting helped diagnose Bartter syndrome, a rare entity in adults. An autoimmune profile showed anti-Scl-70 antibody to be positive, although she did not develop other systemic features of the disease. Our patient responded to a steroid-based regimen potassium supplement, Indomethacin, and aldosterone antagonist with remarkable resolution of symptoms and correction of electrolyte derangement. We reviewed the literature to search for similar cases and included twenty-seven full-length publications on acquired and autoimmune causes of Bartter syndrome. Our case highlights the fact that hypokalemia with metabolic alkalosis in an adult patient should prompt clinicians to evaluate for common and uncommon conditions. While assessing for abnormal conditions, acquired Bartter syndrome should be considered if a patient has an underlying autoimmune, endocrine, or connective tissue disease.

Acute Kidney Injury with Severe Metabolic Alkalosis Caused by Habitual Vomiting in an Alcohol Abuser with Pyloric Stenosis.

A 47-year-old man was complaining of consciousness disorder. He had acute kidney injury, hypokalemia, and severe metabolic alkalosis. Initial treatment using intravenous infusion of 0.9% saline and potassium chloride improved his consciousness. It was clarified that he was a severe alcohol abuser who habitually self-vomited. We diagnosed him with volume depletion and pseudo-Bartter's syndrome due to loss of chloride by habitual vomiting. Gastrointestinal endoscopy demonstrated pyloric stenosis, which was ameliorated by Helicobacter pylori eradication therapy. We should consider volume depletion and pseudo-Bartter's syndrome as differential diagnoses when we encounter patients with acute kidney injury and severe metabolic alkalosis.

Milk-Alkali Syndrome: How Electronic Medical Record Open Notes Helped to Rule Out Cancer.

BACKGROUND Milk-alkali syndrome is caused by excessive consumption of calcium and absorbable alkali and typically presents as a triad of hypercalcemia, acute renal failure, and metabolic alkalosis. In the era of histamine receptor blockers and proton pump inhibitors, the incidence of milk-alkali syndrome has decreased. However, the disease has not been eliminated, due to existing calcium-containing therapies. Here, we present a case of severe milk-alkali syndrome with a challenging initial diagnosis. CASE REPORT We present the case of a 64-year-old man who came to the hospital with encephalopathy. Serologic evaluation revealed acute renal failure, severe hypercalcemia, and metabolic alkalosis. He underwent volume resuscitation, with the initiation of calcitonin. Despite our efforts, the patient developed anuria and proceeded to intermittent hemodialysis. His workup was unrevealing, including an appropriately suppressed parathyroid hormone level, low vitamin D, and normal serum protein electrophoresis and angiotensin converting enzyme levels. Considering his persistent encephalopathy, the team was unable to obtain information from the patient regarding his calcium intake. However, at home, the patient's significant other read his progress notes in the electronic medical record and reported that he consumed at least 1 bottle of calcium carbonate (Tums) every week. Once the encephalopathy resolved, the patient confirmed this information. CONCLUSIONS The search for malignancy in the setting of hypercalcemia was ceased because of the family's at-home electronic medical record use and reporting of Tums overuse. Milk-alkali syndrome, although a rarity, should not be forgotten as a cause of hypercalcemia.

Late onset Bartter syndrome: Bartter syndrome type 2 presenting with isolated nephrocalcinosis and high parathyroid hormone levels mimicking primary hyperparathyroidism.

OBJECTIVES: Nephrocalcinosis is associated with conditions that cause hypercalcemia and the increased urinary excretion of calcium, phosphate, and/or oxalate. A monogenic etiology is found in almost 30% of childhood-onset nephrocalcinosis which is also a common manifestation of primary hyperparathyroidism. We discuss a child with nephrocalcinosis and features mimicking primary hyperparathyroidism. CASE PRESENTATION: A 7-year-old girl presented with nephrocalcinosis. Hypercalciuria, hyperphosphaturia, mild hypercalcemia, hypophosphatemia and elevated parathyroid hormone levels along with normal serum creatinine and absence of hypokalemic alkalosis suggested primary hyperparathyroidism. However, she was ultimately diagnosed with Bartter syndrome type 2 based on the presence of homozygous pathogenic variation in KCNJ1gene. CONCLUSIONS: This is the second reported case of late-onset Bartter syndrome type 2 without hypokalemic alkalosis. Patients with Bartter syndrome may present with high parathyroid hormone levels and hypercalcemia in addition to hypercalciuria. Thus, the present case suggests that the KCNJ1 gene should be included in genetic analysis even in older children with isolated nephrocalcinosis.

Comparison of different modalities of continuous renal replacement therapy with regional sodium citrate anticoagulation in paediatric patients.

BACKGROUND: To evaluate the efficacy and safety of continuous renal replacement therapy (CRRT) modalities with regional sodium citrate anticoagulation (RCA) in children. METHODS: This retrospective study was conducted at the paediatric intensive care unit of Hunan Children's Hospital in China. Medical records of paediatric patients hospitalised for RCA-CRRT between April 2017 and March 2021 were reviewed. Patients received continuous venovenous haemodialysis, continuous venovenous haemofiltration (CVVH), or continuous venovenous haemodiafiltration (CVVHDF). RESULTS: Patients on continuous venovenous haemodialysis (n = 2) were excluded because of their small sample size. The remaining participants were divided into CVVH and CVVHDF groups; 80 patients received CRRT, with 40 and 62 sessions in the CVVH and CVVHDF groups, respectively. The filtre lifespan was longer in the CVVHDF group than in the CVVH group (median value [interquartile range]; 47 [15] hours vs. 35 [17.5] hours; p = 0.029). Compared with the CVVHDF group, the hazard ratio for filtre lifespan in the CVVH group was 3.023 (95% confidence interval 1.820-5.023, p < 0.001). There were no significant differences in ionised calcium levels of the circuits between the two groups at different time points (p < 0.05). Metabolic alkalosis, hyperlactataemia, hypocalcaemia, and hypercalcaemia occurred in both groups, with metabolic alkalosis being the most common complication. No patients in either group experienced sodium citrate accumulation or hypernatraemia. Inter-group differences in the incidence of these complications were not statistically significant (p > 0.05). CONCLUSIONS: Our results suggest that CVVHDF is a better option for RCA-CRRT than CVVH.

Diagnostic Challenge of Congenital Chloride Diarrhea and Ulcerative Colitis Overlap in an Adult Misdiagnosed with Bartter Syndrome: Case Report and Literature Review.

BACKGROUND Congenital chloride diarrhea (CCD) is an autosomal recessive disease that is usually diagnosed in early childhood. Mutations in the SLC26A3 gene have been attributed to the primary etiology of disease development. Patients with CCD usually present with electrolyte disturbances, metabolic alkalosis, and chronic diarrhea. Early diagnosis is essential to prevent long-term complications that often require genetic testing. Bartter syndrome is another congenital disorder that has clinical features similar to CCD, which might cause a delay in diagnosis in a few patients. CASE REPORT We describe the case of a 28-year-old man who was misdiagnosed as having Bartter syndrome when he was 5 months old based on the clinical features of hypokalemia, metabolic alkalosis, and a family history of Bartter syndrome. He had multiple admissions with diarrhea and was diagnosed with ulcerative colitis. Unfortunately, the course was complicated by renal failure, and the patient underwent a kidney transplant. Persistent metabolic alkalosis with diarrhea after transplantation was unusual in Bartter syndrome. Therefore, his primary diagnosis was challenged and suspicion of CCD was raised, which was confirmed by genetic testing. CONCLUSIONS CCD is a rare congenital disorder that requires high clinical suspicion and often a genetic test to confirm diagnosis. Here, we report a patient who was misdiagnosed as having Bartter syndrome until early adulthood owing to several misleading factors. We hope by reporting this case it will raise awareness about CCD in high-prevalence areas and the importance of early diagnosis to prevent serious complications.

The genetic spectrum of Gitelman(-like) syndromes.

PURPOSE OF REVIEW: Gitelman syndrome is a recessive salt-wasting disorder characterized by hypomagnesemia, hypokalemia, metabolic alkalosis and hypocalciuria. The majority of patients are explained by mutations and deletions in the SLC12A3 gene, encoding the Na+-Cl--co-transporter (NCC). Recently, additional genetic causes of Gitelman-like syndromes have been identified that should be considered in genetic screening. This review aims to provide a comprehensive overview of the clinical, genetic and mechanistic aspects of Gitelman(-like) syndromes. RECENT FINDINGS: Disturbed Na+ reabsorption in the distal convoluted tubule (DCT) is associated with hypomagnesemia and hypokalemic alkalosis. In Gitelman syndrome, loss-of-function mutations in SLC12A3 cause impaired NCC-mediated Na+ reabsorption. In addition, patients with mutations in CLCKNB, KCNJ10, FXYD2 or HNF1B may present with a similar phenotype, as these mutations indirectly reduce NCC activity. Furthermore, genetic investigations of patients with Na+-wasting tubulopathy have resulted in the identification of pathogenic variants in MT-TI, MT-TF, KCNJ16 and ATP1A1. These novel findings highlight the importance of cell metabolism and basolateral membrane potential for Na+ reabsorption in the DCT. SUMMARY: Altogether, these findings extend the genetic spectrum of Gitelman-like electrolyte alterations. Genetic testing of patients with hypomagnesemia and hypokalemia should cover a panel of genes involved in Gitelman-like syndromes, including the mitochondrial genome.

[Extreme electrolyte depletion associated with septic shock as a form of presentation of cystic fibrosis]. / Depleción electrolítica extrema asociada con shock séptico como forma de presentación de fibrosis quística.

In the pediatric emergency department, dehydrated children are one of the most frequent causes for consultation, however, the coexistence of hyponatremia with hypochloremia and metabolic alkalosis is rare. The presence of metabolic alkalosis due to chloride depletion has been reported as a form of presentation of Cystic Fibrosis (CF). OBJECTIVE: to describe a case of cystic fibrosis of unusual presen tation in a pediatric patient. CLINICAL CASE: we report a 3-month-old previously healthy male infant who presented with internal environment abnormalities consisting of metabolic alkalosis, hypona tremia, hypokalemia, and extreme hypochloremia associated with septic shock due to mixed viral- bacterial pneumonia (Rhino/enterovirus, Streptococcus pneumoniae, and Staphylococcus aureus). Cys tic fibrosis (CF) was suspected, thus the diagnosis was corroborated by sweat test and genetic study which showed the pathogenic variants c.2834C>T (p.Ser945Leu) and c.3484C>T (p.Arg1162X), both heterozygous. CONCLUSION: special attention should be paid to the existence of hypochloremia with metabolic alkalosis and hyponatremia associated or not with pulmonary disease, suspecting CF as the first option. This consideration becomes more relevant in those countries where the neonatal screening test is not widely available.

Acid-base abnormalities and liver dysfunction.

In addition to the kidneys and lungs, the liver also plays an important role in the regulation of the Acid-Base Equilibrium (ABE). The involvement of the liver in the regulation of ABE is crucial because of its role in lactic acid metabolism, urea production and in protein homeostasis. The main acid-base imbalance that occurs in patients with liver cirrhosis is Respiratory Alkalosis (RAlk). Due to the fact that in these patients additional pathophysiological mechanisms that affect the ABE are present, other disorders may appear which compensate or enhance the primary disorder. Conventional ABE reading models fail to identify and assess the underlying disorders in patients with liver cirrhosis. This weakness of the classical models led to the creation of new physicochemical mathematical models that take into account all the known parameters that develop and affect the ABE. In addition to the RAlk, in patients with liver cirrhosis, metabolic alkalosis (due to hypoalbuminemia), hyponatremic metabolic acidosis, hyperchloremic metabolic acidosis, lactic acidosis and metabolic alkalosis due to urea metabolism are some of the pathophysiological mechanisms that affect the ABE.

Hypocalcemia as the Initial Presentation of Type 2 Bartter Syndrome: A Family Report.

CONTEXT: Bartter syndrome (BS) is a group of rare autosomal-recessive tubulopathies characterized by hypokalemic, hypochloremic metabolic alkalosis in which the primary defect is a deficiency of transporters involved in sodium chloride reabsorption. Type 2 BS results from a defect in the renal outer medullary potassium channel encoded by the KCNJ1 gene. Type 2 BS presents with polyhydramnios, intrauterine growth retardation, prematurity, failure to thrive, polyuria, hypercalciuria, and life-threatening episodes of dehydration. Hypocalcemia is a very rare presenting symptom of BS, with only a few published cases reporting it as the initial manifestation of type 2 BS. OBJECTIVE: To describe a child who presented with hypocalcemic seizure at the age of 2.3 years that was first related to vitamin D deficiency and high-phosphate soft drink consumption. METHODS: Whole exome sequencing (WES) was used to evaluate the biochemical abnormalities of the proband. RESULTS: We identified a previously described homozygous missense mutation c.212C>T, p.T71M in the KCNJ1 gene associated with type 2 BS. Six additional family members with the same mutation and diagnosed clinically with BS are also reported, 2 presenting with hypocalcemia associated with vitamin D deficiency. CONCLUSION: This report expands the clinical spectrum associated with KCNJ1 mutations and emphasizes the role of WES in unsolved cases of hypocalcemia when genetic disease is suspected. It also highlights the hazardous effects of phosphate-containing soft drinks on calcium metabolism.