Clinical features and accompanying findings of Pseudo-Bartter Syndrome in cystic fibrosis

[Cystic fibrosis primarily presenting with pseudo-Bartter syndrome: a report of three cases and literature review]

OBJECTIVES

To summarize the clinical characteristics and genetic variations in children with cystic fibrosis (CF) primarily presenting with pseudo-Bartter syndrome (CF-PBS), with the aim to enhance understanding of this disorder.

METHODS

A retrospective analysis was performed on the clinical data of three children who were diagnosed with CF-PBS in Hunan Children's Hospital from January 2018 to August 2023, and a literature review was performed.

RESULTS

All three children had the onset of the disease in infancy. Tests after admission showed hyponatremia, hypokalemia, hypochloremia, and metabolic alkalosis, and genetic testing showed the presence of compound heterozygous mutation in the CFTR gene. All three children were diagnosed with CF. Literature review obtained 33 Chinese children with CF-PBS, with an age of onset of 1-36 months and an age of diagnosis of 3-144 months. Among these children, there were 29 children with recurrent respiratory infection or persistent pneumonia (88%), 26 with malnutrition (79%), 23 with developmental retardation (70%), and 18 with pancreatitis or extrapancreatic insufficiency (55%). Genetic testing showed that c.2909G>A was the most common mutation site of the CFTR gene, with a frequency of allelic variation of 23% (15/66).

CONCLUSIONS

CF may have no typical respiratory symptoms in the early stage. The possibility of CF-PBS should be considered for infants with recurrent hyponatremia, hypokalemia, hypochloremia, and metabolic alkalosis, especially those with malnutrition and developmental retardation. CFTR genetic testing should be performed as soon as possible to help with the diagnosis of CF.

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.

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.

Morbidity and treatment costs of cystic fibrosis in a middle-income country

Introduction

: Asian children with cystic fibrosis (CF) managed in Malaysia have significant morbidity with limited access to life-sustaining treatments. We determined the morbidity and treatment cost of CF in a resource-limited country.

Methods

This cross-sectional study included all children diagnosed with CF in our centre. Data on clinical presentation, genetic mutation, serial spirometry results and complications were collected. Out-of-pocket (OOP) and healthcare costs over 1 year were retrieved for patients who were alive. Cohen's d and odds ratio (OR) were used to determine the effect size.

Results

Twenty-four patients were diagnosed with CF. Five patients died at a median (range) age of 18 (0.3-22) years. F508deletion (c. 1521_1523delCTT) was found in 20% of the alleles, while 89% of the variants were detected in nine patients. Body mass index (BMI) Z score was >-1.96 in 70.6% of patients. Two thirds (68%) were colonised with Pseudomonas aeruginosa, and this was associated with lower weight (P = 0.009) and BMI (P = 0.02) Z scores. Only 18% had FEV1 Z scores >-1.96. Early symptom onset (d = 0.74), delayed diagnosis (d = 2.07), a low FEF25-75 Z score (d = 0.82) and a high sweat conductance (d = 1.19) were associated with death. Inpatient cost was mainly from diagnostic tests, while medications contributed to half of the outpatient cost.

Healthcare utilisation cost was catastrophic, amounting to 20% of the total income.

Conclusion

Asian children with CF suffer significant complications such as low weight, low lung function and shortened lifespan. P. aeruginosa colonisation was frequent and associated with poor growth. Healthcare cost to parents was catastrophic.

The success of the Cystic Fibrosis Registry of Turkey for improvement of patient care

BACKGROUND

Cystic fibrosis (CF) registries play an essential role in improving disease outcomes of people with CF. This study aimed to evaluate the association of newly established CF registry system in Turkey on follow-up, clinical, growth, treatment, and complications of people with this disease.

METHODS

Age at diagnosis, current age, sex, z-scores of weight, height and body mass index (BMI), neonatal screening results, pulmonary function tests, history of meconium ileus, medications, presence of microorganisms, and follow-up were evaluated and compared to data of people with CF represented in both 2017 and 2019 registry data.

RESULTS

There were 1170 people with CF in 2017 and 1637 in 2019 CF registry. Eight hundred and fourteen people were registered in both 2017 and 2019 of whom z-scores of heights and BMI were significantly higher in 2019 (p = 0.002, p =0.039, respectively). Inhaled hypertonic saline, bronchodilator, and azithromycin usages were significantly higher in 2019 (p =0.001, p = 0.001, p = 0.003, respectively). The percent predicted of forced expiratory volume in  1 sec and forced vital capacity were similar in 2017 and 2019 (88% and 89.5%, p = 0.248 and 84.5% and 87%, p =0.332, respectively). Liver diseases and osteoporosis were significantly higher, and pseudo-Bartter syndrome (PBS) was significantly lower in 2019 (p = 0.011, p = 0.001, p = 0.001, respectively).

CONCLUSIONS

The z-scores of height and BMI were higher, the use of medications that protect and improve lung functions was higher and incidence of PBS was lower in 2019. It was predicted that registry system increased the care of people with CF regarding their follow-up. The widespread use of national CF registry system across the country may be beneficial for the follow-up of people with CF.

Cystic fibrosis newborn screening: Five-year experience from a tertiary care center

BACKGROUND

Newborn screening (NBS) for cystic fibrosis (CF) was implemented in our country on January 1, 2015, based on immunoreactive trypsinogen tests (IRT/IRT). Here, we aimed to evaluate the diagnoses of patients and follow-up process within the first 5 years of NBS from a tertiary care center.

METHODS

This retrospective cohort study was conducted on patients who were admitted to our pediatric pulmonology department for sweat test (ST) via NBS. Patients with CF with negative NBS results and those with CF with positive NBS and joined our follow-up were also investigated. Clinical outcome measures were compared between patients with CF with positive and negative NBS.

RESULTS

Six hundred sixty infants who were referred for ST via NBS were included. Across the entire study population (n = 683), 11.4% of patients had CF (14.1% of had negative NBS in this CF group). The sensitivity of NBS was found as 84.9% and the positive predictive value (PPV) was 9.4%. The median age at diagnosis was older (p < 0.001), reluctance for feeding and Pseudobartter syndrome (PBS) were significantly higher at presentation in the negative NBS group. There was no statistically significant difference between the groups regarding weight-for-age (p = 0.899) and height-for-age (p = 0.491) in the first 2 years' follow-ups.

CONCLUSIONS

Our findings showed the low sensitivity and PPV of NBS; therefore, further studies based on all patients in our country are necessary for new cut-off values. PBS and reluctance for feeding should be alarm symptoms for CF even if the infants had negative NBS. Additionally, later diagnosis of patients who had negative NBS did not affect the nutritional outcomes; we need large-scale prospective studies to optimize nutritional benefits for all infants diagnosed via NBS.

Recent advances in the early treatment of cystic fibrosis: Bridging the gap to highly effective modulator therapy

Highly effective modulator therapy (HEMT) for cystic fibrosis (CF) has been touted as one of the greatest advances to date in CF care. As these therapies are now available for many older children and adults with CF, marked improvement of their nutritional status, pulmonary and gastrointestinal symptoms has been observed. However, most infants and younger children are not current candidates for HEMT due to age and/or cystic fibrosis transmembrane conductance regulator (CFTR) mutation. For these young children, it is essential to provide rigorous monitoring and care to avoid potential disease sequelae while awaiting HEMT availability. The following article highlights recent advances in the care of infants and young children with CF with regard to surveillance and treatment of nutritional, pulmonary, and gastrointestinal disorders. Recent clinical trials in this population are also reviewed.

Year in Review 2020: Multisystemic impact of cystic fibrosis

Clinical care in cystic fibrosis (CF) has continued to advance over the last several years, particularly with the widespread eligibility and use of highly effective modulator therapy. Improved outcomes and longevity of persons with CF (PwCF) have increased recognition of the multisystem impact of the disease on the daily lives of PwCF. This review will cover a broad array of topics, from diagnosis to multisystem effects related to mental health, endocrine, palliative care, reproductive health, otolaryngology, and cardiac issues. Additionally, worldwide care delivery will be reviewed, demonstrating variation in outcomes based on resources and populations served. This review is part of the CF Year in Review 2020 series, focusing on the multi-system effects of CF. This review focuses on articles from Pediatric Pulmonology but also includes articles published in 2020 from other journals that are of particular interest to clinicians.

Pseudo-Bartter syndrome in Chinese children with cystic fibrosis: Clinical features and genotypic findings

OBJECTIVES

To characterize the clinical and genotypic features of cystic fibrosis-associated pseudo-Bartter syndrome (CF-PBS) in Chinese children.

METHODS

We recruited and characterized the clinical manifestations of 12 Chinese children with CF-PBS. Sweat test, blood and urinary analysis, sputum culture, chest and sinus computed tomography, and abdominal ultrasonography were obtained. Whole-exome sequencing, bioinformatics analysis, and Sanger sequencing validation were performed to define the genotypes.

RESULTS

CF-PBS was accompanied by recurrent and/or persistent pneumonia (91.7%), pancreatitis (83.3%), vomiting and/or diarrhea (66.7%), failure to thrive and liver disease (58.3% respectively), among our patients. The predominant organisms found in the airways were Pseudomonas aeruginosa (83.3%) and Staphylococcus aureus (75.0%). The mean concentrations of blood gas and electrolytes were pH 7.58, bicarbonate 40.8 mmol/L, sodium 125.9 mmol/L, chloride 77.5 mmol/L, and potassium 2.6 mmol/L. A high recurrence rate (50.0%) of CF-PBS was observed despite continued electrolyte supplementation during follow-up. In all, 19 different variants of CFTR gene were identified, and 10 of these were found to be novel observations (c.262_266delTTATA[p.L88FfsX21], c.579+2insACAT, c.1210-3C>G, c.1733T>C[p.L578P], c.2236_2246delGAGGCGATACTinsAAAAATC[p.E746KfsX8], c.3068T>G [p.I1023R], c.3635delT[p.V1212AfsX16], c.3859delG[p.G1287EfsX2], c.3964-7A>G and ΔE23 [c.3718-?_3873+?del]). The c.2909G>A[p.G970D] was the most common variant, with an allele frequency of 16.6%. A homozygous genotype of c.1521_1523delCTT[p.F508del] was discovered for the first time in patients of Chinese origin.

CONCLUSIONS

In China, CF-PBS usually presents early and recurs frequently in infancy, accompanied by multiple comorbidities. Recurrence of CF-PBS in school-going patients does occur but is rare. The p.G970D is the most frequent variant, with a significant ethnic tendency of Chinese origin.