Electrolyte abnormalities in cystic fibrosis: systematic review of the literature

Metabolic alkalosis in cystic fibrosis: from vascular volume depletion to impaired bicarbonate excretion

Cystic fibrosis (CF) is the most common life-threatening genetic disease in the United States and among people of European descent. Despite the widespread distribution of the cystic fibrosis transmembrane conductance regulator (CFTR) along kidney tubules, specific renal phenotypes attributable to CF have not been well documented. Recent studies have demonstrated the downregulation of the apical Cl-/HCO3 - exchanger pendrin (Slc26a4) in kidney B-intercalated cells of CF mouse models. These studies have shown that kidneys of both mice and humans with CF have an impaired ability to excrete excess HCO3 -, thus developing metabolic alkalosis when subjected to excess HCO3 - intake. The purpose of this minireview is to discuss the latest advances on the role of pendrin as a molecule with dual critical roles in acid base regulation and systemic vascular volume homeostasis, specifically in CF. Given the immense prevalence of vascular volume depletion, which is primarily precipitated via enhanced chloride loss through perspiration, we suggest that the dominant presentation of metabolic alkalosis in CF is due to the impaired function of pendrin, which plays a critical role in systemic vascular volume and acid base homeostasis.

Diagnosis of cystic fibrosis: a high heterogeneity of symptoms and genotypes in a Brazil population

INTRODUCTION

In highly multiracial populations with inadequate newborn screening, knowledge of the various phenotypic presentations of Cystic Fibrosis (CF) can help reach an early diagnosis. This study aims to describe phenotypes and genotypes at the time of CF diagnosis in a state in the Northeast Region of Brazil.

METHODS

Retrospective cross-sectional study. Clinical data were extracted from the medical records of CF patients. Clinical, laboratory, and genotypic characteristics were described for patients admitted to a tertiary referral center between 2007 and 2021.

RESULTS

Fifty-eight (58) patients were included in the study, 53.5% of whom were diagnosed through clinical suspicion. The median age at diagnosis was 4.7 months (IQR: 1.5-14.8 months). Five patients had false-negative results in the newborn screening. Faltering growth was the most frequent clinical manifestation. Bronchiectasis and a history of pneumonia predominated in those older than ten, while thinness, underweight, and electrolyte imbalances were more frequent in children under two. Sequencing of the CFTR gene identified 27 genotypes, with at least one class I-III variant in all patients, and nine variants that are rare, previously undescribed, or have uncertain significance (619delA, T12991, K162Q, 3195del6, 1678del > T, 124del123bp, 3121-3113 A > T). The most frequent alleles were p.Phe508del, p.Gly542*, p.Arg334Trp, and p.Ser549Arg.

CONCLUSIONS

Malnutrition and electrolyte imbalances were the most frequent phenotypes for children < 2 years and were associated with genotypes including 2 class I-III variants. Rare and previously undescribed variants were identified. The p.Gly542*, p.Arg334Trp, and p.Ser549Arg alleles were among the most frequent variants in this population.

Occurrence of COVID-19 in cystic fibrosis patients: a review

Cystic fibrosis (CF) is a genetic ailment caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. This autosomal recessive disorder is characterized by diverse pathobiological abnormalities, such as the disorder of CFTR channels in mucosal surfaces, caused by inadequate clearance of mucus and sputum, in addition to the malfunctioning of mucous organs. However, the primary motive of mortality in CF patients is pulmonary failure, which is attributed to the colonization of opportunistic microorganisms, formation of resistant biofilms, and a subsequent decline in lung characteristics. In December 2019, the World Health Organization (WHO) declared the outbreak of the radical coronavirus disease 2019 (COVID-19) as a worldwide public health crisis, which unexpectedly spread not only within China but also globally. Given that the respiration system is the primary target of the COVID-19 virus, it is crucial to investigate the impact of COVID-19 on the pathogenesis and mortality of CF patients, mainly in the context of acute respiratory distress syndrome (ARDS). Therefore, the goal of this review is to comprehensively review the present literature on the relationship between cystic fibrosis, COVID-19 contamination, and development of ARDS. Several investigations performed during the early stages of the virus outbreak have discovered unexpected findings regarding the occurrence and effectiveness of COVID-19 in individuals with CF. Contrary to initial expectancies, the rate of infection and the effectiveness of the virus in CF patients are lower than those in the overall population. This finding may be attributed to different factors, including the presence of thick mucus, social avoidance, using remedies that include azithromycin, the fairly younger age of CF patients, decreased presence of ACE-2 receptors, and the effect of CFTR channel disorder on the replication cycle and infectivity of the virus. However, it is important to notice that certain situations, which include undergoing a transplant, can also doubtlessly boost the susceptibility of CF patients to COVID-19. Furthermore, with an increase in age in CF patients, it is vital to take into account the prevalence of the SARS-CoV-2 virus in this population. Therefore, ordinary surveillance of CF patients is vital to evaluate and save the population from the capability of transmission of the virus given the various factors that contribute to the spread of the SARS-CoV-2 outbreak in this precise organization.

Updates in hyponatremia and hypernatremia

PURPOSE OF REVIEW

Hyponatremia and hypernatremia are commonly encountered electrolyte abnormalities that require timely and careful intervention, as they can be associated with significant morbidity and mortality.

RECENT FINDINGS

This review article addresses the etiology, presentation, diagnosis, and management of both hyponatremia and hypernatremia, emphasizing the latest advancements and emerging trends in pediatric care.

SUMMARY

A methodical approach is needed to accurately assess and treat hyponatremia and hypernatremia. Both conditions continue to rely on serum and urine testing, however newer tests such as copeptin and stimulated testing may hold promise to further refine testing in the future.

ESPEN-ESPGHAN-ECFS guideline on nutrition care for cystic fibrosis

BACKGROUND

Nutritional status is paramount in Cystic Fibrosis (CF) and is directly correlated with morbidity and mortality. The first ESPEN-ESPGHAN-ECFS guidelines on nutrition care for infants, children, and adults with CF were published in 2016. An update to these guidelines is presented.

METHODS

The study was developed by an international multidisciplinary working group in accordance with officially accepted standards. Literature since 2016 was reviewed, PICO questions were discussed and the GRADE system was utilized. Statements were discussed and submitted for on-line voting by the Working Group and by all ESPEN members.

RESULTS

The Working Group updated the nutritional guidelines including assessment and management at all ages. Supplementation of vitamins and pancreatic enzymes remains largely the same. There are expanded chapters on pregnancy, CF-related liver disease, and CF-related diabetes, bone disease, nutritional and mineral supplements, and probiotics. There are new chapters on nutrition with highly effective modulator therapies and nutrition after organ transplantation.

Risk of CFTR-related disorders and cystic fibrosis in an Italian cohort of CRMS/CFSPID subjects in preschool and school age

The identification of cystic fibrosis screening-positive, inconclusive diagnosis (CFSPID) in infants is a controversial outcome of newborn screening for cystic fibrosis (CF). Today, despite improvements in the knowledge of CFSPID and the description of several cohorts, little data are available on cohorts with a follow-up period of more than 6 years. In this study, we report the outcomes of an Italian cohort of CFSPID individuals with CFSPID or formerly CFTR-related disorders (CFTR-RD) (CFSPID > CFTR-RD) or diagnosed with CF (CFSPID > CF). This was an observational and multicentre Italian study collecting clinical data on CFSPID born between the period January 1, 2011, and December 13, 2019. A total of 268 participants were included: 243 with persistent CFSPID, 7 with CFSPID > CFTR-RD, and 18 with CFSPID > CF. The trend of sweat chloride (SC) values, percentage of definitive diagnoses, lung function in school-aged children, and development of CF-related complications were evaluated. At the end of the observation period, almost 80% of the individuals with CFSPID did not have a conclusive diagnosis. A total of 29 children (10.8%) transitioned to a diagnosis of CF for pathological SC values (≥ 60 mmol/L) or multi-organ involvement, and 18 (6.7%) to CFTR-RD. Children who were followed up for > 6 years (median age, 7.5 years; range, 6.04-10.5) had normal lung function and were pancreatic sufficient, and the evolution in CF was only present in two cases.

CONCLUSION

Most Italian preschool and school-aged children with CFSPID did not have a conclusive diagnosis, and progression to CF was unlikely in children > 6 years of age. An annual follow-up could be indicated to identify early evolution in clinical features consistent with a CFTR-RD.

WHAT IS KNOWN

• Cystic Fibrosis newborn screening identifies also subjects with an inconclusive diagnosis (CFSPID). • Over time a variable percentage of CFSPIDs will be diagnosed as CF. • Little data is available on CFSPIDs with a follow-up period of more than six years.

WHAT IS NEW

• 80% of Italian preschool and school-age CFSPIDs not have a conclusive diagnosis. • Italian preschool and school-age CFSPIDs have normal lung function and are pancreatic sufficient. • Annual follow-up after 6 years is recommended in CFSPID with abnormal LCI2.5 or with a CF-causing variant in trans with a VVCC.

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.

Cystic fibrosis

Cystic fibrosis (CF) is an autosomal recessive genetic disease caused by variants in the gene encoding for the cystic fibrosis transmembrane conductance regulator (CFTR) protein. CFTR dysfunction results in abnormal chloride and bicarbonate transport in epithelial cells, leading to a multiorgan disease dominated by respiratory and digestive manifestations. The respiratory disease, which is characterized by airway mucus plugging, chronic bacterial infection and progressive development of bronchiectasis, may lead to chronic respiratory failure, which is the main cause of premature death in people with CF. Over the past 50 years, major progress has been obtained by implementing multidisciplinary care, including nutritional support, airway clearance techniques and antibiotics in specialized CF centers. The past 10 years have further seen the progressive development of oral medications, called CFTR modulators, that partially restore ion transport and lead to a major improvement in clinical manifestations and lung function, presumably resulting in longer survival. Although an increasing proportion of people with CF are being treated with CFTR modulators, challenges remain regarding access to CFTR modulators due to their high cost, and their lack of marketing approval and/or effectiveness in people with rare CFTR variants. The anticipated increase in the number of adults with CF and their aging also challenge the current organization of CF care. The purpose of this review article is to describe current status and future perspective of CF disease and care.

Changes of androgen and corticosterone metabolites excretion and conversion in cystic fibrosis

Cystic fibrosis (CF) is a life-threatening inherited disease related to a mutation in the CFTR gene, that leads to serious health complications such as chronic pulmonary infections, pancreatic insufficiency, dysfunction of the sweat glands and reproductive system. For the first time, we have described the profile of corticosterone and androgen metabolites in urine, as well as the activity of enzymes involved in steroid genesis and metabolism in people with CF, using gas chromatography/mass spectrometry. A significant reduction in the excretion of most of the measured metabolites in CF was found. These differences were observed in the group of progestagen metabolites, as well as among metabolites of corticosterone and androgens. We revealed higher activities of 17β-hydroxysteroid dehydrogenase and 17,20-lyase in the Δ4 pathway compared with controls, what can promote the androgen synthesis through the backdoor androgen pathway. We have also found the increased conversion activity of 11-oxyganated steroids by 5a-reductase in backdoor pathway. Levels of the most potent and vital androgens (testosterone and dihydrotestosterone) are comparable in both groups. However, the excretion of dehydroepiandrosterone was lower in CF. Decreased cholesterol lipoprotein levels may contribute to limited intracellular cholesterol supply and reduced adrenal steroidogenesis in CF individuals. Changes in the activity of some steroidogenesis enzymes may suggest the presence of some peripheral adaptive mechanisms in CF to maintain androgen balance in the body despite the limited sufficiency of secretion by the adrenal cortex.

Outdoor temperature and circulating sodium in children with acute gastroenteritis

BACKGROUND

Dysnatremias are frequent in acute gastroenteritis. High outdoor temperatures have been associated with hyponatremia in both adults and the elderly, but no data are available among children with gastroenteritis.

METHODS

Children <10 years of age admitted to the emergency department of the Policlinico Hospital, Milan (Italy) between 2009 and 2019 with acute moderate-severe gastroenteritis were enrolled. The association between hyponatremia (sodium < 135 mmol/L) and daily mean levels of temperature or apparent temperature from day of admission up to 14 days before was analyzed by multivariable logistic regression models.

RESULTS

In 202 included children (46% females), we observed an increased risk of hyponatremia per unit increase in outdoor temperature of the sixth, eighth and ninth day before admission [Odds Ratio = 1.24 (95% Confidence Interval: 1.04-1.47), 1.14 (1.01-1.28), and 1.14 (1.01-1.28), respectively]. Analyses considering average temperature levels of the ten days preceding admission returned similar findings as well as those on apparent temperature.

CONCLUSIONS

Our data suggest the existence of an association between outdoor temperature and circulating sodium levels in children with acute gastroenteritis. The role of meteorological conditions on electrolyte imbalance should be further explored in the context of climate change.

IMPACT

The role of meteorological variables in the development of dysnatremias has been demonstrated in children and adolescents with cystic fibrosis. This study shows for the first time that higher outdoor temperatures are associated with a higher risk of hyponatremia in children with gastroenteritis. In the context of climate change, the role of external climate conditions on the risk of electrolyte imbalance in children should be more and more considered and explored in future studies.

Update on the management of vitamins and minerals in cystic fibrosis

Advancements in respiratory and nutrition management have significantly improved the survival of patients with cystic fibrosis (CF). With the availability of several nutrition interventions such as oral/enteral nutrition supplements, enteric‐coated pancreatic enzymes, and water‐miscible CF‐specific vitamin supplements, frank vitamin deficiencies—with the exception of vitamin D—are rarely encountered in current clinical practice. Whereas they were previously considered as micronutrients, our current understanding of fat‐soluble vitamins and minerals as antioxidants, immunomodulators, and disease biomarkers has been evolving. The impact of highly effective modulators on the micronutrient status of patients with CF remains elusive. This narrative review focuses on the updates on the management of fat‐soluble vitamins and other micronutrients in CF in the current era and identifies the gaps in our knowledge.

Recent Advances in Wearable Potentiometric pH Sensors

Wearable sensors reflect the real-time physiological information and health status of individuals by continuously monitoring biochemical markers in biological fluids, including sweat, tears and saliva, and are a key technology to realize portable personalized medicine. Flexible electrochemical pH sensors can play a significant role in health since the pH level affects most biochemical reactions in the human body. pH indicators can be used for the diagnosis and treatment of diseases as well as the monitoring of biological processes. The performances and applications of wearable pH sensors depend significantly on the properties of the pH-sensitive materials used. At present, existing pH-sensitive materials are mainly based on polyaniline (PANI), hydrogen ionophores (HIs) and metal oxides (MOx). In this review, we will discuss the recent progress in wearable pH sensors based on these sensitive materials. Finally, a viewpoint for state-of-the-art wearable pH sensors and a discussion of their existing challenges are presented.

Nutrition management in adults with cystic fibrosis

Cystic fibrosis (CF) is a lethal, monogenic, autosomal recessive disease with manifestations in multiple organ systems, including the lungs and gastrointestinal tract, that impact adequate nutrition. This review discusses important aspects of nutrition in adults with CF with a focus on exocrine pancreatic insufficiency, CF-related diabetes, and gastrointestinal motility, as well as how advanced lung disease, CF transmembrane conductance regulator modulators, and aging impact nutrition in 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.

Case report: Cystic fibrosis with kwashiorkor: A rare presentation in the era of universal newborn screening

BACKGROUND

Universal newborn screening changed the way medical providers think about the presentation of cystic fibrosis (CF). Before implementation of universal screening, it was common for children with CF to present with failure to thrive, nutritional deficiencies, and recurrent infections. Now, nearly all cases of CF are diagnosed by newborn screening shortly after birth before significant symptoms develop. Therefore, providers often do not consider this illness in the setting of a normal newborn screen. Newborn screening significantly decreases the risk of complications in early childhood, yet definitive testing should be pursued if a patient with negative newborn screening presents with symptoms consistent with CF, including severe failure to thrive, metabolic alkalosis due to significant salt losses, or recurrent respiratory infections.

CASE PRESENTATION

We present a case of a 6-month-old infant male with kwashiorkor, severe edema, multiple vitamin deficiencies, hematemesis secondary to coagulopathy, and diffuse erythematous rash, all secondary to severe pancreatic insufficiency. His first newborn screen had an immunoreactive trypsinogen (IRT) value below the state cut-off value, so additional testing was not performed, and his growth trajectory appeared reassuring. He was ultimately diagnosed with CF by genetic testing and confirmatory sweat chloride testing, in the setting of his parents being known CF carriers and his severe presentation being clinically consistent with CF. Acutely, management with supplemental albumin, furosemide, potassium, and vitamin K was initiated to correct the presenting hypoalbuminemia, edema, and coagulopathy. Later, pancreatic enzyme supplementation and additional vitamins and minerals were added to manage ongoing deficiencies from pancreatic insufficiency. With appropriate treatment, his vitamin deficiencies and edema resolved, and his growth improved.

CONCLUSION

Due to universal newborn screening, symptomatic presentation of CF is rare and presentation with kwashiorkor is extremely rare in resource-rich communities. The diagnosis of CF was delayed in our patient because of a normal newborn screen and falsely reassuring growth, which after diagnosis was determined to be secondary to severe edematous malnutrition. This case highlights that newborn screening is a useful but imperfect tool. Clinicians should continue to have suspicion for CF in the right clinical context, even in the setting of normal newborn screen results.

Urinary sodium/creatinine ratio is a predictor for fractional sodium excretion and related to age in patients with cystic fibrosis

Electrolyte disturbances are common in patients with cystic fibrosis (CF). Current guidelines on monitoring sodium status are based on research in a small group of infants and require blood sampling. The aim of this study was to evaluate urinary salt parameters as a surrogate for sodium-status in different age-groups. Blood and urine samples for electrolytes were collected from 222 patients followed at the Ghent University Hospital CF-center. Fractional sodium excretion (FENa) and several urinary parameters were calculated. Clinical characteristics did not differ according to sodium status, defined as FENa <0.5%. ROC analysis demonstrated that sodium/creatinine ratio (UNa/Creat) predicted the sodium status most accurately with high sensitivity and specificity (97 and 91% respectively). The UNa/Creat cut-off predicting a FENa <0.5% differed significantly according to age. The UNa/Creat is an excellent marker for the sodium status defined as a FENa <0.5%. However, different cut-offs according to age category should be applied.

Electrochemical and Fluorescent Properties of Crown Ether Functionalized Graphene Quantum Dots for Potassium and Sodium Ions Detection

The concentration of sodium and potassium ions in biological fluids, such as blood, urine and sweat, is indicative of several basic body function conditions. Therefore, the development of simple methods able to detect these alkaline ions is of outmost importance. In this study, we explored the electrochemical and optical properties of graphene quantum dots (GQDs) combined with the selective chelating ability of the crown ethers 15-crown-5 and 18-crown-6, with the final aim to propose novel composites for the effective detection of these ions. The results obtained comparing the performances of the single GQDs and crown ethers with those of the GQDs-15-crown-5 and GQDs-18-crown-6 composites, have demonstrated the superior properties of these latter. Electrochemical investigation showed that the GQDs based composites can be exploited for the potentiometric detection of Na+ and K+ ions, but selectivity still remains a concern. The nanocomposites showed the characteristic fluorescence emissions of GQDs and crown ethers. The GQDs-18-crown-6 composite exhibited ratiometric fluorescence emission behavior with the variation of K+ concentration, demonstrating its promising properties for the development of a selective fluorescent method for potassium determination.

Characteristics of electrolyte imbalance and pseudo-bartter syndrome in hospitalized cystic fibrosis children and adolescents

INTRODUCTION

Pseudo-Bartter syndrome (PBS) is a rare manifestation of Cystic fibrosis (CF) and can often be the initial presentation in these patients, however, due to significantly overlapping symptoms it is often misdiagnosed as simple dehydration or Bartter syndrome. The objective of our study was to highlight the key features of PBS and electrolyte imbalance in CF patients helping in early and prompt diagnosis.

METHOD

We performed a retrospective study from January 2015 to December 2019 at the Aga Khan University Hospital (AKUH), Pakistan. CF patients aged from 1-18 years, admitted at AKUH were enrolled and their laboratory data and individual charts were reviewed. Patients were categorized into three groups based on their serum electrolyte profile and their clinical findings were compared.

RESULT

We enrolled 72 CF patients, out of which 42 (58%) were categorized into the Normal Electrolyte (NE) group, 19 (26%) into the Electrolyte Imbalance (EI) group and 11 (15%) in the PBS group. Out of 11 cases, 6 (54.54%) patients in PBS group presented with features consistent with PBS leading to CF diagnosis labeled as "early presenters". Mean age of patients in the PBS group was 3.81± 0.86 years and their age at diagnosis were significantly lower as compared to other groups. Gastrointestinal disturbances including diarrhea, vomiting and constipation were more common in the EI and PBS groups. Polyuria was most common in the PBS (72%) group. Length of hospital stay showed no significant difference.

CONCLUSION

Pseudo-Bartter syndrome can be a presenting feature of cystic fibrosis. Electrolyte imbalance should be anticipated in hospitalized CF children and adolescent.

Cystic fibrosis in the kidney: new lessons from impaired renal HCO3- excretion

PURPOSE OF REVIEW

A key role of cystic fibrosis transmembrane conductance regulator (CFTR) in the kidney has recently been uncovered. This needs to be integrated into the understanding of the developed phenotypes in cystic fibrosis (CF) patients.

RECENT FINDINGS

In the beta-intercalated cells of the collecting duct , CFTR functions in very similar terms as established in the exocrine pancreatic duct and both CFTR and SLC26A4 (pendrin) orchestrate regulated HCO3- secretion. Like in the pancreas, the hormone secretin is a key agonist to activate renal HCO3- secretion. In mice lacking CFTR or pendrin, acute and chronic base challenges trigger marked metabolic alkalosis because collecting duct base secretion is defective. Also in CF patients, the ability to acutely increase renal HCO3- excretion is markedly reduced.

SUMMARY

The now much enlarged understanding of CFTR in the kidney may permit the measurement of challenged urine HCO3- excretion as a new biomarker for CF. We suggest a new explanation for the electrolyte disorder in CF termed Pseudo-Bartter Syndrome. The hallmark electrolyte disturbance features of this can be well explained by a reduced function of collecting duct Cl-/HCO3- exchange. Eventually, we suggest the diagnostic term distal renal tubular alkalosis to cover those disturbances that causes metabolic alkalosis by a reduced collecting duct base secretion.

Impaired renal HCO3 - secretion in CFTR deficient mice causes metabolic alkalosis during chronic base-loading

AIM

Cystic fibrosis patients have an increased risk of developing metabolic alkalosis presumably as a result of altered renal HCO₃ ^- handling. In this study, we directly assess the kidneys' ability to compensate for a chronic base-load in the absence of functional CFTR.

METHODS

Comprehensive urine and blood acid-base analyses were done in anaesthetized WT mice or mice lacking either CFTR or pendrin, with or without 7 days of oral NaHCO₃ loading. The in vivo experiments were complemented by a combination of immunoblotting and experiments with perfused isolated mouse cortical collecting ducts (CCD).

RESULTS

Base-loaded WT mice maintained acid-base homeostasis by elevating urinary pH and HCO₃ ^- excretion and decreasing urinary net acid excretion. In contrast, pendrin KO mice and CFTR KO mice were unable to increase urinary pH and HCO₃ ^- excretion and unable to decrease urinary net acid excretion sufficiently and thus developed metabolic alkalosis in response to the same base-load. The expression of pendrin was increased in response to the base-load in WT mice with a paralleled increased pendrin function in the perfused CCD. In CFTR KO mice, 7 days of base-loading did not upregulate pendrin expression and apical Cl^- /HCO₃ ^- exchange function was strongly blunted in the CCD.

CONCLUSION

CFTR KO mice develop metabolic alkalosis during a chronic base-load because they are unable to sufficiently elevate renal HCO₃ ^- excretion. This can be explained by markedly reduced pendrin function in the absence of CFTR.

Electrolyte and Acid-Base Disorders Triggered by Aminoglycoside or Colistin Therapy: A Systematic Review

Aminoglycoside or colistin therapy may alter the renal tubular function without decreasing the glomerular filtration rate. This association has never been extensively investigated. We conducted a systematic review of the literature following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses recommendations. Databases searched included United States National Library of Medicine, Excerpta Medica, and Web of Science. For the final analysis, we evaluated 46 reports, published after 1960, describing 82 cases. A total of 286 electrolyte and acid-base disorders were reported. Hypomagnesemia, hypokalemia, and hypocalcemia were reported in more than three quarter of cases. Further disorders were, in decreasing order of frequency, metabolic alkalosis, hyponatremia, hypophosphatemia, hypouricemia, hypernatremia, and metabolic acidosis. Six electrolyte and acid-base disorders were reported in seven cases, five in 12 cases, four in 16 cases, three in 31 cases, two in 11 cases, and one in five cases. Laboratory features consistent with a loop of Henle/distal tubular dysfunction were noted in 56 (68%), with a proximal tubular dysfunction in three (3.7%), and with a mixed dysfunction in five (6.1%) cases. The laboratory abnormality was unclassified in the remaining 18 (22%) cases. Treatment with aminoglycosides or colistin may trigger a proximal tubular or, more frequently, a loop of Henle/distal tubular dysfunction.

Clinical manifestation, laboratory findings, and outcome of children with cystic fibrosis over a 10-year period in South Iran

Background

Cystic fibrosis (CF) is a monogenic hereditary disease with diverse complications, which substantially reduce the quality of life and longevity of patients. With regard to the scarcity of information on epidemiological aspects of this disease in Iran, we aimed to examine the current status of pediatric CF patients in a tertiary referral center in south Iran.

Results

Medical records of 105 patients (51% female) with the mean age of 16.3 ± 34.4 months were reviewed. Twelve patients (13.3%) had siblings with CF. Failure to thrive and respiratory symptoms were the most common presentations. Elevated liver enzymes and steatorrhea were detected in over half of tested patients, while abnormal serum albumin level, urinalysis, positive urine cultures, and positive acute phase reactants were noticed in less than half of the patients. Mild increase in pulmonary artery blood pressure was the most common finding of echocardiography. Increased liver echogenicity was the top finding of abdominopelvic sonography. Out of 42 available patients, 19 (45.2%) died with the mean age of 54.4 ± 101.8 months. The highest rate of mortality was observed in the 2–6 years old age group (42.9%).

Conclusion

Increased liver echogenicity was the most common finding in hepatobiliary evaluation. Mild increase in pulmonary artery blood pressure was the most common finding of echocardiography.

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.

Dehydrated patient without clinically evident cause: A case report

BACKGROUND

Patients affected by cystic fibrosis can present with metabolic alkalosis such as Bartter’s syndrome. In this case report we want to underline this differential diagnosis and we aimed focusing on the suspect of cystic fibrosis, also in case of a negative newborn screening.

CASE SUMMARY

In a hot August –with a mean environmental temperature of 36 °C– an 8-mo-old female patient presented with severe dehydration complicated by hypokalemic metabolic alkalosis, in absence of fever, diarrhea and vomiting. Differential diagnosis between cystic fibrosis and tubulopathies causing metabolic alkalosis (Bartter’s Syndrome) was considered. We started intravenous rehydration with subsequent improvement of clinical conditions and serum electrolytes normalization. We diagnosed a mild form of cystic fibrosis (heterozygous mutations: G126D and F508del in the cystic fibrosis transmembrane conductance regulator gene). The trigger factor of this condition had been heat exposure.

CONCLUSION

When facing a patient with hypokalemic metabolic alkalosis, cystic fibrosis presenting with Pseudo-Bartter’s syndrome should be considered in the differential diagnosis, even if the newborn screening was negative.

Cystic Fibrosis Presenting as Pseudo-Bartter Syndrome: An Important Diagnosis that is Missed!

Cystic fibrosis (CF), an autosomal recessive disorder, occurs due to mutations in CFTR gene resulting in impaired cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel function in various epithelia. In addition to the well-known pulmonary and pancreatic morbidities, CF is characterized by electrolyte and acid-base abnormalities- hypochloremia, hyponatremia, hypokalemia and metabolic alkalosis. These are collectively known as Pseudo-Bartter syndrome, as similar abnormalities are seen in Bartter syndrome- an inherited tubulopathy affecting thick ascending limb of loop of Henle. There may be a significant clinical overlap between the Classic Bartter syndrome, Gitelman syndrome and CF presenting as Pseudo-Bartter syndrome, especially in early childhood. This review focuses on Pseudo-Bartter syndrome in CF, its pathogenesis and differentiation from Bartter/Gitelman syndrome. Other causes of metabolic abnormalities resembling Bartter syndrome are also highlighted.

Sodium Status and Replacement in Children and Adults Living with Cystic Fibrosis: A Narrative Review

Patients with cystic fibrosis (CF) have a two- to four-fold higher sodium chloride sweat content compared with healthy controls. This high sweat salt loss increases the risk for electrolyte disturbances, associated with subacute or chronic complications. Sodium status therefore needs to be adequately monitored and salt intake adjusted to individual needs. The lack of current evidence to formulate specific recommendations and assess sodium status is reflected in a variability of recommendations in international guidelines. This narrative review presents an overview of the current evidence. Infants with CF in particular are at risk for severe sodium deficiency, potentially leading to metabolic alkalosis due to low intake and high sweat losses. More research on the assessment of sodium status and efficacy of sodium chloride supplements in the population of patients with CF, especially given the changing era of CF transmembrane conductance regulator modulatory treatment, is warranted.

A wearable sensor for the detection of sodium and potassium in human sweat during exercise

The SwEatch platform, a wearable sensor for sampling and measuring the concentration of electrolytes in human sweat in real time, has been improved in order to allow the sensing of two analytes. The solid contact ion-sensitive electrodes (ISEs) for the detection of Na⁺ and K⁺ have been developed in two alternative formulations, containing either poly(3,4-ethylenedioxythiophene) (PEDOT) or poly(3-octylthiophene-2,5-diyl) (POT) as a conductive polymer transducing component. The solution-processable POT formulation simplifies the fabrication process, and sensor to sensor reproducibility has been improved via partial automation using an Opentron® automated pipetting robot. The resulting electrodes showed good sensitivity (52.4 ± 6.3 mV/decade (PEDOT) and 56.4 ± 2.2 mV/decade (POT) for Na⁺ ISEs, and 45.7 ± 7.4 mV/decade (PEDOT) and 54.3 ± 1.5 mV/decade (POT) for K⁺) and excellent selectivity towards potential interferents present in human sweat (H⁺, Na⁺, K⁺, Mg²⁺, Ca²⁺). The 3D printed SwEatch platform has been redesigned to incorporate a double, mirrored fluidic unit which is capable of drawing sweat from the skin through passive capillary action and bring it in contact with two independent electrodes. The potentiometric signal generated by the electrodes is measured by an integrated electronics board, digitised and transmitted via Bluetooth to a laptop. The results obtained from on-body trials on athletes during cycling show a relatively small increase in sodium (1.89 mM-2.97 mM) and potassium (3.31 mM-7.25 mM) concentrations during the exercise period of up to 90 min.

Osmoregulation in children with cystic fibrosis

Hyponatremia is not rare in cystic fibrosis and might be due to several mechanisms. An endocrine and renal imbalance in water and salt homeostasis was suggested. To address this hypothesis, we assessed the urinary concentrating and diluting ability in 12 cystic fibrosis patients (6 females, 6 males) and in two control groups: 14 children with pneumonia (9 females, 5 males) and in 13 healthy children (9 females, 4 males). Renal concentrating ability was evaluated following overnight water deprivation. Urine osmolality was not significantly different between groups. Renal diluting ability was assessed by means of a water-load test. This provoked a decrease in urine osmolality, as well as an increase in diuresis and solute-free water excretion. These changes were comparable among groups.Conclusion: Children with cystic fibrosis show a preserved renal concentrating and diluting capacity. A generalized endocrine and renal imbalance in water and salt homeostasis therefore appears unlikely.What is Known:•Hyponatremia sometimes occurs in cystic fibrosis.What is New:•Osmoregulation is normal in cystic fibrosis.

Cystic fibrosis in Turkey: First data from the national registry

BACKGROUND

Cystic fibrosis (CF) care has been implemented in Turkey for a long time; however, there had been no patient registry. For this purpose, the Turkish National CF Registry was established. We present the first results of registry using data collected in 2017.

METHODS

The data were collected using a data-entry software system, which was accessed from the internet. Demographic and annually recorded data consisted of 15 and 79 variables, respectively.

RESULTS

There were 1170 patients registered from 23 centers; the estimated coverage rate was 30%. The median age at diagnosis was 1.7 years (median current age: 7.3 years); 51 (4.6%) patients were aged over 18 years. Among 293 patients who were under 3 years of age, 240 patients (81.9%) were diagnosed through newborn screening. Meconium ileus was detected in 65 (5.5%) patients. Genotyping was performed in 978 (87.4%) patients and 246 (25.2%) patients' mutations were unidentified. The most common mutation was deltaF508 with an allelic frequency of 28%, followed by N1303K (4.9%). The median FEV1% predicted was 86. Chronic colonization with Pseudomonas aeruginosa was seen in 245 patients. The most common complication was pseudo-Bartter syndrome in 120 patients. The median age of death was 13.5 years in a total of 15 patients.

CONCLUSIONS

Low coverage rate, lack of genotyping, unidentified mutations, and missing data of lung functions are some of our greatest challenges. Including data of all centers and reducing missing data will provide more accurate data and help to improve the CF care in Turkey in the future.

Should isolated Pseudo-Bartter syndrome be considered a CFTR-related disorder of infancy?

BACKGROUND

Infants that are negative to cystic fibrosis (CF) newborn screening (NBS) programs, or in countries without NBS, may present with metabolic alkalosis and severe salt depletion, a well-known clinical manifestation of CF termed Pseudo-Bartter syndrome (PBS). Here, we report the cases of three CF-negative children, who carry rare mutations in the CF transmembrane conductance regulator (CFTR) gene, and, for whom, PBS was the only manifestation of CFTR protein dysfunction. There is no diagnostic label for these cases.

METHODS

Medical records of patients followed at our Cystic Fibrosis Centre were revised and data were collected for all patients who presented with an isolated PBS. The syndrome was defined as an episode of dehydration with low levels of serum sodium (<134mmol/L), potassium ( <3.4mmol/L), and chloride ( <100mmol/L), with metabolic alkalosis (bicarbonatemia >27mmol/L) in the absence of renal tubulopathy.

RESULTS

Three out of 73 (4%) CF infants presented with a severe metabolic alkalosis with salt depletion; two of these required admission to the intensive care unit. Two infants had a negative NBS, and one was identified as a CF carrier. Sweat test was repeatedly in the negative/borderline ranges for all patients. Less than two CF causing mutations were identified (F508del/R1070W, F508del; L467F/P5L, R1066H/P5L). During a mean follow-up of 9 years, the children had no other CF manifestations.

CONCLUSION

We suggest that PBS as the sole manifestation of CFTR dysfunction might be considered a CFTR-related disorder of infancy.

Physiology of sweat gland function: The roles of sweating and sweat composition in human health

The purpose of this comprehensive review is to: 1) review the physiology of sweat gland function and mechanisms determining the amount and composition of sweat excreted onto the skin surface; 2) provide an overview of the well-established thermoregulatory functions and adaptive responses of the sweat gland; and 3) discuss the state of evidence for potential non-thermoregulatory roles of sweat in the maintenance and/or perturbation of human health. The role of sweating to eliminate waste products and toxicants seems to be minor compared with other avenues of excretion via the kidneys and gastrointestinal tract; as eccrine glands do not adapt to increase excretion rates either via concentrating sweat or increasing overall sweating rate. Studies suggesting a larger role of sweat glands in clearing waste products or toxicants from the body may be an artifact of methodological issues rather than evidence for selective transport. Furthermore, unlike the renal system, it seems that sweat glands do not conserve water loss or concentrate sweat fluid through vasopressin-mediated water reabsorption. Individuals with high NaCl concentrations in sweat (e.g. cystic fibrosis) have an increased risk of NaCl imbalances during prolonged periods of heavy sweating; however, sweat-induced deficiencies appear to be of minimal risk for trace minerals and vitamins. Additional research is needed to elucidate the potential role of eccrine sweating in skin hydration and microbial defense. Finally, the utility of sweat composition as a biomarker for human physiology is currently limited; as more research is needed to determine potential relations between sweat and blood solute concentrations.

Phenotypic spectrum and genetic heterogeneity of cystic fibrosis in Sri Lanka

Background

Cystic fibrosis has been largely under-diagnosed and thus, limited data is available on the incidence of cystic fibrosis in Sri Lanka. Our aim is to describe the phenotypic and genotypic spectrum of children with cystic fibrosis in Sri Lanka.

Case presentation

This report describes 10 unrelated cystic fibrosis cases with phenotypic features of cystic fibrosis and abnormal or intermediate sweat tests. The most common phenotypic features in this sample of symptomatic patients were persistent or recurrent lower respiratory tract infections, failure to thrive and Pseudo-Bartter syndrome. Altogether 7 cystic fibrosis causing mutations were identified in 10 patients. Except delta F508 which is the commonest mutation worldwide all the other mutations detected in Sri Lankan patients are rare mutations. 1161delC and V456A detected in our patients are South Asian mutations. The other mutations such as [C.1282C > G; C.2738A > G], C.53 + 1G > C, 2184insA and a deletion encompassing exons 4 to 11 have been reported previously from European patients with cystic fibrosis.

Conclusion

These cases highlight the importance of considering the diagnosis of cystic fibrosis in children and young adults presenting with persistent respiratory tract infections associated with severe malnutrition and Pseudo-Bartter syndrome, especially in low income countries where newborn screening for cystic fibrosis is not available. The spectrum of CFTR mutations in Sri Lanka is heterogeneous and possibly linked to genetic flow from Indian subcontinent and Europe. The common mutations should be identified by sequencing the entire CFTR gene in adequate number of cystic fibrosis patients in order to design a mutation panel for common regional mutations.

Wearable Potentiometric Sensors for Medical Applications

Wearable potentiometric sensors have received considerable attention owing to their great potential in a wide range of physiological and clinical applications, particularly involving ion detection in sweat. Despite the significant progress in the manner that potentiometric sensors are integrated in wearable devices, in terms of materials and fabrication approaches, there is yet plenty of room for improvement in the strategy adopted for the sample collection. Essentially, this involves a fluidic sampling cell for continuous sweat analysis during sport performance or sweat accumulation via iontophoresis induction for one-spot measurements in medical settings. Even though the majority of the reported papers from the last five years describe on-body tests of wearable potentiometric sensors while the individual is practicing a physical activity, the medical utilization of these devices has been demonstrated on very few occasions and only in the context of cystic fibrosis diagnosis. In this sense, it may be important to explore the implementation of wearable potentiometric sensors into the analysis of other biofluids, such as saliva, tears and urine, as herein discussed. While the fabrication and uses of wearable potentiometric sensors vary widely, there are many common issues related to the analytical characterization of such devices that must be consciously addressed, especially in terms of sensor calibration and the validation of on-body measurements. After the assessment of key wearable potentiometric sensors reported over the last five years, with particular attention paid to those for medical applications, the present review offers tentative guidance regarding the characterization of analytical performance as well as analytical and clinical validations, thereby aiming at generating debate in the scientific community to allow for the establishment of well-conceived protocols.

Clinical characterization and diagnosis of cystic fibrosis through exome sequencing in Chinese infants with Bartter-syndrome-like hypokalemia alkalosis

Cystic fibrosis (CF) is a fatal autosomal-recessive disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. CF is characterized by recurrent pulmonary infection with obstructive pulmonary disease. CF is common in the Caucasian population but is rare in the Chinese population. The symptoms of early-stage CF are often untypical and may sometimes manifest as Bartter syndrome (BS)-like hypokalemic alkalosis. Therefore, the ability of doctors to differentiate CF from BS-like hypokalemic alkalosis in Chinese infants is a great challenge in the timely and accurate diagnosis of CF. In China, sporadic CF has not been diagnosed in children younger than three years of age to date. Three infants, who were initially admitted to our hospital over the period of June 2013 to September 2014 with BS-like hypokalemic alkalosis, were diagnosed with CF through exome sequencing and sweat chloride measurement. The compound heterozygous mutations of the CFTR gene were detected in two infants, and a homozygous missense mutation was found in one infant. Among the six identified mutations, two are novel point mutations (c.1526G > C and c.3062C > T) that are possibly pathogenic. The three infants are the youngest Chinese patients to have been diagnosed with sporadic CF at a very early stage. Follow-up examination showed that all of the cases remained symptom-free after early intervention, indicating the potential benefit of very early diagnosis and timely intervention in children with CF. Our results demonstrate the necessity of distinguishing CF from BS in Chinese infants with hypokalemic alkalosis and the significant diagnostic value of powerful exome sequencing for rare genetic diseases. Furthermore, our findings expand the CFTR mutation spectrum associated with CF.

Hyponatremia in children with acute respiratory infections: A reappraisal

Hyponatremia (<135 mmol/L), typically associated with an elevated anti-diuretic hormone level, is common among children admitted with bronchiolitis, pneumonia, or pulmonary exacerbation of cystic fibrosis. The main consequences of acute hyponatremia include cerebral edema and Ayus-Arieff pulmonary edema. A widespread belief is that, in children with pneumonia or bronchiolitis, hyponatremia results from inappropriate anti-diuresis. By contrast, the pathogenic role of extracellular fluid volume depletion or decreased effective circulating blood volume is underscored. Considering the prevalence of hyponatremia, sodium determination is advised on admission in children diagnosed with bronchiolitis, pneumonia, or pulmonary exacerbation of cystic fibrosis. There is no necessity to do anything beyond reassessing the appropriateness of fluid therapy in cases with mild (130-134 mmol/L) hyponatremia. In children with sodium <130 mmol/L, the underlying etiology is sometimes evident from history and physical findings. Given that clinical assessment of fluid volume status is difficult in hyponatremia, further laboratory evaluation is often required in these patients. An increase in sodium level ≤6 mmol/L per day is currently considered the therapeutic goal in all cases. Emergency correction with a 2 mL/kg body weight bolus of 3.0% saline over 10-15 min intravenously is advised in cases with severe symptoms due to hyponatremia and in cases with symptoms, even if mild, due to a rapid-onset (<48 h) of hyponatremia (two additional doses are administered if the patient's condition does not improve).

A Textile-Based Stretchable Multi-Ion Potentiometric Sensor

A textile-based wearable multi-ion potentiometric sensor array is described. The printed flexible sensors operate favorably under extreme mechanical strains (that reflect daily activity) while offering attractive real-time noninvasive monitoring of electrolytes such as sodium and potassium.

Clinical Practice Guidelines From the Cystic Fibrosis Foundation for Preschoolers With Cystic Fibrosis

Cystic fibrosis (CF) clinical care guidelines exist for the care of infants up to age 2 years and for individuals ≥6 years of age. An important gap exists for preschool children between the ages of 2 and 5 years. This period marks a time of growth and development that is critical to achieve optimal nutritional status and maintain lung health. Given that disease often progresses in a clinically silent manner, objective and sensitive tools that detect and track early disease are important in this age group. Several challenges exist that may impede the delivery of care for these children, including adherence to therapies. A multidisciplinary committee was convened by the CF Foundation to develop comprehensive evidence-based and consensus recommendations for the care of preschool children, ages 2 to 5 years, with CF. This document includes recommendations in the following areas: routine surveillance for pulmonary disease, therapeutics, and nutritional and gastrointestinal care.

Infection in cystic fibrosis: impact of the environment and climate

In many countries numbers of adults with cystic fibrosis (CF) exceed that of children, with median survival predicted to surpass 50 years. Increasing longevity is, in part, due to intensive therapies including eradication of early infection and suppressive therapies and pulmonary exacerbations. Initial infections with common CF pathogens are thought to arise from the natural environment. We review the impact of climate and environment on infection in CF. Specifically, several studies indicate that higher ambient temperatures, proximity to the equator and the summer season may be linked to the increased prevalence of Pseudomonas aeruginosa in people with CF. The environment may also play an important role in the acquisition of Gram negative organisms other than P. aeruginosa. There is emerging data suggesting that climatic and environmental factors are likely to impact on the risk of infection with NTM and fungi in people which are found extensively throughout the natural environment.

Magnesium in cystic fibrosis--Systematic review of the literature

BACKGROUND

The metabolism of sodium, potassium, and chloride and the acid-base balance are sometimes altered in cystic fibrosis. Textbooks and reviews only marginally address the homeostasis of magnesium in cystic fibrosis.

METHODS

We performed a search of the Medical Subject Headings terms (cystic fibrosis OR mucoviscidosis) AND (magnesium OR hypomagnes[a]emia) in the US National Library of Medicine and Excerpta Medica databases.

RESULTS

We identified 25 reports dealing with magnesium and cystic fibrosis. The results of the review may be summarized as follows. First, hypomagnesemia affects more than half of the cystic fibrosis patients with advanced disease; second, magnesemia, which is normally age-independent, relevantly decreases with age in cystic fibrosis; third, aminoglycoside antimicrobials frequently induce both acute and chronic renal magnesium-wasting; fourth, sweat magnesium concentration was normal in cystic fibrosis patients; fifth, limited data suggest the existence of an impaired intestinal magnesium balance. Finally, stimulating observations suggest that magnesium supplements might achieve an improvement in respiratory muscle strength and mucolytic activity of both recombinant and endogenous deoxyribonuclease.

CONCLUSIONS

The first comprehensive review of the literature confirms that, despite being one of the most prevalent minerals in the body, the importance of magnesium in cystic fibrosis is largely overlooked. In these patients, hypomagnesemia should be sought once a year. Furthermore, the potential of supplementation with this cation deserves more attention.

Low sodium status in cystic fibrosis-as assessed by calculating fractional Na(+) excretion-is associated with decreased growth parameters

BACKGROUND

In CF infants, normonatremic Na(+) depletion (NNaD), identified by fractional Na(+) excretion (FENa) values <0.5%, was recently linked to impaired growth. Our paper investigates the relationship between FENa and growth in CF children >2years.

METHODS

FENa values were calculated in 35 CF and 24 control children, and tested for correlations with z-scores for weight, height and BMI.

RESULTS

All CF children and controls had normal plasma Na(+) concentrations. A total of 25 of 35 (71.4%) CF patients had decreased FENa values <0.5% (group I). FENa results of 10 CF patients (group II) and 23/24 controls (group III) were normal. In Na(+)-depleted CF children, compared to normal controls, mean z-scores for weight (-0.18±0.87 vs +1.03±0.57, p<0.001), height (-0.06±0.89 vs +0.53±0.72, p=0.009) and BMI (-0.22±0.87 vs +1.00±1.06, p<0.001) were significantly reduced. Also, we found positive correlations between FENa values and z-scores for weight (r=0.521), height (r=0.292) and BMI (r=0.468), respectively.

CONCLUSION

NNaD may contribute to poor growth in CF.

Clinical presentation of air leak in an infant with undiagnosed cystic fibrosis: a case report

Introduction

Air leak is a well-recognized complication of advanced cystic fibrosis in older children and adults but is extremely rare in infants. To the best of our knowledge, this is the youngest reported pediatric case of an air leak from a major airway.

Case presentation

A 4-month-old Yamani baby girl with a family history of cystic fibrosis initially presented with a history of a persistent paroxysmal cough for 3 weeks and vomiting for 1 week. Laboratory evaluation indicated pseudo-Bartter’s syndrome. Imaging showed a tracheal tear with pneumomediastinum and subcutaneous emphysema that was treated conservatively.

Conclusions

This case highlights the possibility of air leak in the population of young patients with cystic fibrosis and it shows a successful conservative management of tracheal tear. Physicians should consider cystic fibrosis in infants presenting with air leak.