Evaluation of salt supplementation in CF infants

Diet management in congenital diarrheas and enteropathies - general concepts and disease-specific approach, a narrative review

Congenital diarrheas and enteropathies (CODE) are a group of rare, heterogenous, monogenic disorders that lead to chronic diarrhea in infancy. Definitive treatment is rarely available, and supportive treatment is the mainstay. Nutritional management in the form of either specialized formulas, restrictive diet, or parenteral nutrition support in CODE with poor enteral tolerance is the cornerstone of CODE treatment and long-term growth. The evidence to support the use of specific diet regimens and nutritional approaches in most CODE disorders is limited due to the rarity of these diseases and the scant published clinical experience. The goal of this review was to create a comprehensive guide for nutritional management in CODE, based on the currently available literature, disease mechanism, and the PediCODE group experience. Enteral diet management in CODE can be divided into 3 distinct conceptual frameworks: nutrient elimination, nutrient supplementation, and generalized nutrient restriction. Response to nutrient elimination or supplementation can lead to resolution or significant improvement in the chronic diarrhea of CODE and resumption of normal growth. This pattern can be seen in CODE due to carbohydrate malabsorption, defects in fat absorption, and occasionally in electrolyte transport defects. In contrast, general diet restriction is mainly supportive. However, occasionally it allows parenteral nutrition weaning or reduction over time, mainly in enteroendocrine defects and rarely in epithelial trafficking and polarity defects. Further research is required to better elucidate the role of diet in the treatment of CODE and the appropriate diet management for each disease.

Somatic growth outcomes in response to an individualized neonatal sodium supplementation protocol

Objective

Evaluate the impact of a sodium (Na) supplementation protocol based upon urine Na concentration on growth parameters and morbidities.

Study Design

Retrospective cohort study of infants 260/7-336/7 weeks gestational age (GA) cared for before (2012-15, n = 225) and after (2016-20, n = 157) implementation of the protocol. Within- and between-group changes over time were assessed using repeated measures generalized linear models.

Results

For infants 260/7-296/7 weeks GA, utilization of the protocol was associated with increased mean body weight z-score at 8-weeks postnatal age, increased mean head circumference z-score at 16-weeks postnatal age, and decreased time on mechanical ventilation (all p < 0.02). No impact on growth was identified for infants 30-336/7 weeks GA. Incidences of hypertension, hypernatremia, bronchopulmonary dysplasia, and culture positive sepsis were unaffected by the protocol.

Conclusion

Protocolized Na supplementation results in improved growth and reduced time on invasive mechanical ventilation in extremely preterm infants without increasing incidence of morbidities.

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.

Nutritional management of people living with cystic fibrosis throughout life and disease continuum: Changing times, new challenges

Cystic fibrosis (CF) is a genetic disease caused by mutations in the gene encoding for the ion channel cystic fibrosis transmembrane conductance regulator (CFTR). The management of CF disease has evolved in recent decades from treating downstream disease manifestations affecting the airways, the lungs and the gastrointestinal system to addressing the CFTR gene defect. The advent of CFTR modulators, which correct the functionality of the defective CFTR, contributes to reshaping the landscape of CF demographics, prognosis and therapies, including nutritional management. A spectrum of clinical manifestations is emerging within the same patient population where undernutrition and nutritional deficiencies coexist with excessive weight gain and metabolic derangements. Such contrasting presentations challenge current practices, require adjustments to traditional approaches, and involve more individualised interventions. This narrative review examines the current state of knowledge on the nutritional management of people living with cystic fibrosis from early life to adulthood in the era of CFTR modulation.

A unique presentation of hyponatremia and seizures in a 2-month-old child with cystic fibrosis: a case report

Cystic fibrosis is an autosomal recessive disorder that causes a broad range of clinical findings and can present unusually as electrolyte disturbance, such as hyponatremia that causes seizures in children.

CASE PRESENTATION

We report a case of a 2-month-old infant who presented with an episode of grand mal seizure induced by hyponatremia and moderate episodes of milky vomiting after breastfeeding.

CLINICAL DISCUSSION

Proper investigations showed normal cardiac and renal functions. Ultrasonography showed no pathological changes. Laboratory tests performed showed hyponatremia, mild hypokalemia, and hypochloremia. Urinary electrolyte results were normal. While broadening the scope of differential diagnosis in order to reach a final diagnosis, the sweat chloride level was elevated, which confirmed the diagnosis of cystic fibroses.

CONCLUSION

We aim to share our case to keep cystic fibroses in mind as a differential diagnosis when dealing with hyponatremic seizures in children.

Nutritional Care in Children with Cystic Fibrosis

Patients with cystic fibrosis (CF) are prone to malnutrition and growth failure, mostly due to malabsorption caused by the derangement in the chloride transport across epithelial surfaces. Thus, optimal nutritional care and support should be an integral part of the management of the disease, with the aim of ameliorating clinical outcomes and life expectancy. In this report, we analyzed the nutrition support across the different ages, in patients with CF, with a focus on the relationships with growth, nutritional status, disease outcomes and the use of the CF transmembrane conductance regulator (CFTR) modulators. The nutrition support goal in CF care should begin as early as possible after diagnosis and include the achievement of an optimal nutritional status to support the growth stages and puberty development in children, that will further support the maintenance of an optimal nutritional status in adult life. The cornerstone of nutrition in patients with CF is a high calorie, high-fat diet, in conjunction with a better control of malabsorption due to pancreatic enzyme replacement therapy, and attention to the adequate supplementation of fat-soluble vitamins. When the oral caloric intake is not enough for reaching the anthropometric nutritional goals, supplemental enteral feeding should be initiated to improve growth and the nutritional status. In the last decade, the therapeutic possibilities towards CF have grown in a consistent way. The positive effects of CFTR modulators on nutritional status mainly consist in the improvement in weight gain and BMI, both in children and adults, and in an amelioration in terms of the pulmonary function and reduction of exacerbations. Several challenges need to be overcome with the development of new drugs, to transform CF from a fatal disease to a treatable chronic disease with specialized multidisciplinary care.

Urine sodium to urine creatinine ratio as a marker of total body sodium in infants with intestinal failure

PURPOSE

Urine sodium (UNa) is a measure of total body sodium in infants with intestinal failure (IF) but can be misleading as it does not reflect volume status. Urine sodium to urine creatinine ratio (UNa:UCr) may offer a more accurate measure, but is not routinely used. This study compares UNa:UCr to UNa as a maker of sodium status in infants with IF.

METHODS

A retrospective review of infants with IF, from a single center, from 2018 to 2020 was conducted (REB H20-00,816). IF etiology, intestinal anatomy, nutritional intake, urine electrolytes and anthropometrics were collected. Linear mixed effects models adjusting for repeated measures were used to associate UNa and UNa:UCr with weight gain and sodium intake.

RESULTS

Twenty-two infants with a median gestational age of 31 weeks were included. IF etiology included gastroschisis (41%), necrotizing enterocolitis (23%), and intestinal perforation (14%). Infants had an average of 3 paired UNa and UNa:UCr measures for a total of 74 paired measurements. UNa:UCr more strongly correlated with sodium intake compared to UNa (R = 0.25, p = 0.032 vs. R = 0.10, p = 0.38). Overall, neither UNa (p = 0.21) nor UNa:UCr (p = 0.16) were significantly correlated with weight gain. However, for infants receiving ≤50% nutrition enterally, weight gain correlated with UNa (p = 0.01) and UNa:UCr (p = 0.01). UNa:UCr >35 predicted adequate growth regardless of enteral intake (92% sensitivity, 59% specificity).

CONCLUSION

UNa:UCr is a measure of total body sodium that correlates with sodium intake in infants with IF. Our study indicates UNa:UCr >35 is associated with adequate growth and can be used to guide further validation studies.

Brazilian Guidelines for Nutrition in Cystic Fibrosis

OBJECTIVE

To develop a scientific consensus on nutrition in cystic fibrosis.

METHODS

Sixteen coordinators elaborated relevant questions on nutritional therapy in cystic fibrosis, which were divided into six sections: nutritional assessment, nutritional recommendations, nutritional intervention, dietary counseling, special situations and enzyme replacement, and gastrointestinal manifestations. Two to three specialists in the field were responsible for each section and obtaining answers formulated based on standardized bibliographic searches. The available literature was searched in the PubMed®/MEDLINE database, after training and standardization of search strategies, to write the best level of evidence for the questions elaborated. Issues related to disagreement were discussed until a consensus was reached among specialists, based on the current scientific literature.

RESULTS

Forty-two questions were prepared and objectively answered, resulting in a consensus of nutritional therapy in cystic fibrosis.

CONCLUSION

This work enabled establishing a scientific consensus for nutritional treatment of cystic fibrosis patients.

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.

A physiological approach to fluid and electrolyte management of the preterm infant: Review

Despite the fact that hundreds of thousands of preterm infants receive parenteral fluids each year, study of optimal fluid and electrolyte management in this population is limited. Compared to older children and adults, preterm infants have an impaired capacity to regulate water and electrolyte balance. Appropriate fluid and electrolyte management is critical for optimal care of low birth weight or sick infants, as fluid overload and electrolyte abnormalities pose significant morbidity. This review highlights basic physiological principles which need to be applied when prescribing parenteral fluids and builds upon published literature to outline a rational approach to initial fluid and electrolyte management of the preterm infant.

Gastrointestinal, Pancreatic, and Hepatic Manifestations of Cystic Fibrosis in the Newborn

Gastrointestinal, pancreatic, and hepatic signs and symptoms represent the most common presentation of early disease among patients with cystic fibrosis and may be the initial indication of disease. Regardless of whether cystic fibrosis is diagnosed early by newborn screening or later by clinical course, the impact of gastrointestinal, pancreatic, and hepatic manifestations on early life is nearly ubiquitous. Conditions strongly linked with cystic fibrosis, such as meconium ileus and pancreatic insufficiency, must be recognized and treated early to optimize both short- and long-term care. Similarly, less specific conditions such as reflux, poor weight gain, and cholestasis are frequently encountered in infants with cystic fibrosis. In this population, these conditions may present unique challenges in which early interventions may have significant influence on both short- and long-term morbidity and mortality outcomes.

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.

Nutritional Status in the First 2 Years of Life in Cystic Fibrosis Diagnosed by Newborn Screening

OBJECTIVE

To evaluate nutritional status and associated factors in a cystic fibrosis (CF) cohort diagnosed by newborn screening and followed up to month 24.

METHODS

A prospective longitudinal multicenter study assessing nutritional status according to pancreatic status, feeding modalities, prescriptions, pulmonary outcome, and biological nutritional parameters.

RESULTS

One hundred and five infants were recruited and 99 completed the study. Nutritional care management prevented undernutrition and stunting in those with exocrine pancreatic sufficiency (EPS), but affected (13/87) 15% and (21/86) 24%, respectively, of infants with exocrine pancreatic insufficiency (EPI). The logistic regression model found a positive association between both weight and length z scores "at risk" at month 24, and initial pulmonary symptoms (odds ratio [OR] 0.06, P < 0.01 and OR 0.08, P < 0.01, respectively); these symptoms were less frequent when age at first visit was earlier than 1.2 months (33% vs 67%, P = 0.02); stunting was also associated with high-calorie density intake and Staphylococcus aureus (OR 0.05, P = 0.01 and OR 0.17, P < 0.01). Pulmonary outcome did not differ according to pancreatic status; breast-feeding for at least 3 months delayed first acquisition of Pseudomonas aeruginosa. Despite sodium and fat-soluble vitamin supplementation, half of both cohorts had low urinary sodium output and half of the EPI cohort had low vitamin D levels.

CONCLUSIONS

Our data shed light on the fact that stunting was more frequent than undernutrition, while both parameters involved only patients with pancreatic insufficiency. Modalities of feeding were not associated with nutritional status; breast-feeding may provide some protection against acquisition of P aeruginosa.

Brazilian guidelines for the diagnosis and treatment of cystic fibrosis

Cystic fibrosis (CF) is an autosomal recessive genetic disorder characterized by dysfunction of the CFTR gene. It is a multisystem disease that most often affects White individuals. In recent decades, various advances in the diagnosis and treatment of CF have drastically changed the scenario, resulting in a significant increase in survival and quality of life. In Brazil, the current neonatal screening program for CF has broad coverage, and most of the Brazilian states have referral centers for the follow-up of individuals with the disease. Previously, CF was limited to the pediatric age group. However, an increase in the number of adult CF patients has been observed, because of the greater number of individuals being diagnosed with atypical forms (with milder phenotypic expression) and because of the increase in life expectancy provided by the new treatments. However, there is still great heterogeneity among the different regions of Brazil in terms of the access of CF patients to diagnostic and therapeutic methods. The objective of these guidelines was to aggregate the main scientific evidence to guide the management of these patients. A group of 18 CF specialists devised 82 relevant clinical questions, divided into five categories: characteristics of a referral center; diagnosis; treatment of respiratory disease; gastrointestinal and nutritional treatment; and other aspects. Various professionals working in the area of CF in Brazil were invited to answer the questions devised by the coordinators. We used the PubMed database to search the available literature based on keywords, in order to find the best answers to these questions.

Congenital Sodium Diarrhea: A Form of Intractable Diarrhea, With a Link to Inflammatory Bowel Disease

Congenital diarrheal disorders (CDDs) represent a group of challenging clinical conditions for pediatricians because of the severity of the presentation and the broad range of possible differential diagnoses. CDDs arise from alterations in the transport of nutrients and electrolytes across the intestinal mucosa, from enterocyte and enteroendocrine cell differentiation and/or polarization defects, and from the modulation of the intestinal immune response. Advances were made recently in deciphering the etiology and pathophysiology of one of these disorders, congenital sodium diarrhea (CSD). CSD refers to an intractable diarrhea of intrauterine onset with high fecal sodium loss. CSD is clinically and genetically heterogeneous. A syndromic form of CSD features choanal and intestinal atresias as well as recurrent corneal erosions. Small bowel histology frequently detects an epithelial "tufting" dysplasia. It is autosomal recessively inherited, and caused by SPINT2 mutations. The nonsyndromic form of CSD can be caused by dominant activating mutations in GUCY2C, encoding intestinal receptor guanylate cyclase C (GC-C), and by autosomal recessive SLC9A3 loss-of-function mutations. SLC9A3 encodes Na/H antiporter 3, the major intestinal brush border Na/H exchanger, and a downstream target of GC-C. A number of patients with GUCY2C and SLC9A3 mutations developed inflammatory bowel disease. Both the number of recognized CDD forms as well as the number of underlying disease genes are gradually increasing. Knowledge of these CDD genes enables noninvasive, next-generation gene panel-based testing to facilitate an early diagnosis in CDD. Primary Na/H antiporter 3 and GC-C malfunction is implicated as a predisposition for inflammatory bowel disease in subset of patients.

ESPEN-ESPGHAN-ECFS guidelines on nutrition care for infants, children, and adults with cystic fibrosis

BACKGROUND

Malnutrition is both a frequent feature and a comorbidity of cystic fibrosis (CF), with nutritional status strongly associated with pulmonary function and survival. Nutritional management is therefore standard of care in CF patients. ESPEN, ESPGHAN and ECFS recommended guidelines to cover nutritional management of patients with CF.

METHODS

The guidelines were developed by an international multidisciplinary working group in accordance with officially accepted standards. The GRADE system was used for determining grades of evidence and strength of recommendation. Statements were discussed, submitted to Delphi rounds, reviewed by ESPGHAN and ECFS and accepted in an online survey among ESPEN members.

RESULTS

The Working Group recommends that initiation of nutritional management should begin as early as possible after diagnosis, with subsequent regular follow up and patient/family education. Exclusive breast feeding is recommended but if not possible a regular formula is to be used. Energy intake should be adapted to achieve normal weight and height for age. When indicated, pancreatic enzyme and fat soluble vitamin treatment should be introduced early and monitored regularly. Pancreatic sufficient patients should have an annual assessment including fecal pancreatic elastase measurement. Sodium supplementation is recommended and a urinary sodium:creatinine ratio should be measured, corresponding to the fractional excretion of sodium. If iron deficiency is suspected, the underlying inflammation should be addressed. Glucose tolerance testing should be introduced at 10 years of age. Bone mineral density examination should be performed from age 8-10 years. Oral nutritional supplements followed by polymeric enteral tube feeding are recommended when growth or nutritional status is impaired. Zinc supplementation may be considered according to the clinical situation. Further studies are required before essential fatty acids, anti-osteoporotic agents, growth hormone, appetite stimulants and probiotics can be recommended.

CONCLUSION

Nutritional care and support should be an integral part of management of CF. Obtaining a normal growth pattern in children and maintaining an adequate nutritional status in adults are major goals of multidisciplinary cystic fibrosis centers.

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.

Dietary intake and nutritional status of micronutrients in adults with cystic fibrosis in relation to current recommendations

An increased prevalence of cystic fibrosis (CF) related complications such as impaired bone health and diabetes has accompanied increased survival of patients with CF. This review was conducted to determine the extent to which adults with CF are meeting current nutrition recommendations for micronutrients in association with CF-related complications management. Although dietary intake and nutritional status in CF has improved significantly in recent decades, micronutrient status seems to have diverged. While vitamin A and E intakes appear adequate, frequent vitamin D and K deficiency/insufficiency and compromised bone health in CF, occurs despite supplementation. Although deficiency of water-soluble vitamins and minerals is uncommon, ongoing surveillance will enhance overall health outcomes, particularly in cases of CF-related liver disease and deteriorated lung function and bone health. Salt and fluid status in CF may also need attention due to diminished thirst sensation and voluntary rehydration. Further investigation in micronutrient status optimisation in CF will inform the development of more effective and targeted nutrition therapies to enable integration of more refined recommendations for micronutrient intakes in CF based on individual needs and disease progression.

Effect of sodium deficiency on growth of surgical infants: a retrospective observational study

BACKGROUND/AIM

Sodium is thought to be critical to growth. Infants who have an ileostomy may suffer from growth faltering, as sodium losses from stomas may be excessive. Urinary sodium measurements may indicate which patients could benefit from sodium supplementation; however, there is no consensus on what level of urinary sodium should be the cutoff for intervention. Our aim was to determine whether there is a relationship between urinary sodium and growth in infants undergoing ileostomy, colostomy and cystostomy.

METHODS

Following audit approval, a retrospective observational study of patient notes and chemical pathology data was carried out. All infants <1 year of age that had an ileostomy, colostomy, or cystostomy procedure between February 1997 and January 2014 were included. Patients' weights, urinary and serum sodium and potassium levels and clinical variables were recorded until discharge. Weights were converted to Z-scores for analysis.

RESULTS

Forty patients were identified whose notes were available for review and who had at least three urinary sodium measurements. During their hospital stay, 11 (28%) maintained weight within normal limits (Z-scores -2 to +2, 15 (38%) were moderately malnourished (-3 to -2) and 14 (35%) severely malnourished (<-3). Thirty patients had at least one urinary sodium <10 mmol/litre, six patients had their lowest recorded urinary sodium between 10 and 30 mmol/litre and only four patients had all their urinary sodium measurements >30 mmol litre. Electrolyte data were not normally distributed so that correlations between electrolytes and growth were tested using the non-parametric Spearman rank correlation coefficient. Urinary sodium levels positively correlated with growth (r = 0.3071, p < 0.0001), as did serum sodium levels (r = 0.2620, p = 0.0059) whereas there was no relationship between urine or serum potassium and growth.

CONCLUSIONS

Poor growth is frequent in this group of patients and appears to be linked with sodium levels. Further work is necessary to draw up guidelines for appropriate sodium supplementation.

Electrolyte abnormalities in cystic fibrosis: systematic review of the literature

BACKGROUND

Cystic fibrosis per se can sometimes lead to hyponatremia, hypokalemia, hypochloremia or hyperbicarbonatemia. This tendency was first documented 60 years ago and has subsequently been confirmed in single case reports or small case series, most of which were retrospective. However, this issue has not been addressed analytically. We have therefore systematically reviewed and analyzed the available literature on this subject.

METHODS

This was a systematic review of the literature.

RESULTS

The reports included in this review cover 172 subacute and 90 chronic cases of electrolyte imbalances in patients with cystic fibrosis. The male:female ratio was 1.57. Electrolyte abnormalities were mostly associated with clinically inapparent fluid volume depletion, mainly affected patients aged ≤2.5 years, frequently tended to recur and often were found before the diagnosis of cystic fibrosis was established. Subacute presentation often included an history of heat exposure, vomiting, excessive sweating and pulmonary infection. History of chronic presentation, in contrast, was often inconspicuous. The tendency to hypochloremia, hypokalemia and metabolic alkalosis was similar between subacute and chronic patients, with hyponatremia being more pronounced (P < 0.02) in subacute compared to chronic presentations. Subacute cases were treated parenterally; chronic ones were usually managed with oral salt supplementation. Retention of urea and creatinine was documented in 38 % of subacute cases.

CONCLUSIONS

The findings of our review suggest that physicians should be aware that electrolyte abnormalities can occur both as a presenting and a recurring feature of cystic fibrosis.

Total body sodium depletion and poor weight gain in children and young adults with an ileostomy: a case series

Patients with high-output small bowel ostomies are at risk for total body sodium depletion (TBSD), defined as a urine sodium level <10 mmol/L. Failure to thrive (FTT) as a consequence of TBSD has been reported in neonates with ileostomies; however, this has not been well described in older children. The records of all children beyond the age of infancy with a small bowel ostomy cared for in our Children's Intestinal Rehabilitation Program from 2010-2012 were reviewed. Four patients between the ages of 18 months and 19 years were identified as having TBSD. All 4 patients experienced unintentional weight loss, despite adequate energy intake based on calculated needs, which was associated with a urine sodium level ≤10 mmol/L. With the supplementation of sodium, either enteral or intravenous, all patients demonstrated improved weight gain and correction of TBSD. The following cases suggest that the relationship between TBSD and FTT may extend well beyond the neonatal period and possibly into adulthood. We advise that patients of all ages with high stoma output have routine urine sodium levels checked, particularly in the setting of weight loss or poor gain. Furthermore, instances of TBSD should be treated with sodium supplementation. Further research is needed to better understand the relationship between TBSD and FTT and to establish intervention guidelines.

Urinary sodium to creatinine ratio in healthy infants

Rationale Sodium is essential for adequate growth; the daily requirement in infants is 2 to 3 mmol/kg/d. Objectives The study aimed to establish a reference range for the ratio of urinary sodium (UNa) to creatinine (UCr) in healthy infants in a suburban setting in the United States. Methods UNa and UCr were measured in healthy infants and UNa:UCr was calculated. Daily sodium intake was estimated by parental report. Results Mean estimated sodium intake in the 71 infants was 1.34 mEq/kg/d (95% confidence interval = 1.23-1.44). The mean UNa:UCr was 11.73 (95% confidence interval = 10.24-13.23) and did not differ significantly in age-groups. There was no direct correlation between sodium intake and UNa:UCr in healthy infants. Conclusions The UNa:UCr was 11.73 in this population of healthy infants. This likely reflects the appropriate physiologic response to sodium intake in the study population, which was at the lower end of the usual estimated needs for infants.

Prevalence of hyponatremia at diagnosis and factors associated with the longitudinal variation in serum sodium levels in infants with cystic fibrosis

OBJECTIVE

To determine the prevalence of hyponatremia at diagnosis in patients with cystic fibrosis and identify the factors associated with changes in serum sodium concentration over time.

STUDY DESIGN

This longitudinal study investigated whether variations in serum sodium concentration were associated with age, diet, infection status, and climate/temperature. Multivariate analysis was performed using the random-effects model for longitudinal data.

RESULTS

Hyponatremia at diagnosis was observed in 19 of the 20 patients (95%). Factors identified as associated with variations in serum sodium concentration were diet (P = .008) and climate/temperature (P = .005). Intake of solid foods appeared to greatly increase the serum sodium concentration (increase of 5 mEq/L after introduction of solid foods); however, a confounding factor between diet and age cannot be definitively ruled out. Climate/temperature contributed in an inverse way; a 1°C-increase in ambient temperature was associated with a 0.5-mEq/L decrease in serum sodium concentration.

CONCLUSION

Infants with cystic fibrosis who feed on breast milk or formula and live in a high-temperature environment are at increased risk for hyponatremia, even when receiving a higher salt intake in accordance with recommendations.

A review of pathophysiology and management of fetuses and neonates with meconium ileus for the pediatric surgeon

PURPOSE

Meconium ileus (MI) is the earliest clinical manifestation of cystic fibrosis (CF), occurring in up to 20% of patients with CF. Our aim was to review and integrate current knowledge about the diagnosis and management of fetuses and neonates with MI that may aid the pediatric surgeon in caring for these patients.

METHODS

We identified areas of interest including pathophysiology, prenatal diagnosis, nonoperative and operative management, postoperative management, and prognosis. We performed a Medline search using the search term meconium ileus for English language articles published in the last 20 years. We reviewed reference lists to identify other articles of historical significance.

RESULTS

Meconium ileus is primarily associated with CF transmembrane (conductance) regulator mutations F508del, G542X, W1282X, R553X, and G551D, and modifier genes have been found to explain approximately 17% of the phenotypic variability. Mouse, pig, and ferret models for CF demonstrate neonatal bowel obstruction mimicking MI. Sonographic findings of hyperechoic masses and dilated bowel in a high-risk fetus are suggestive of MI. Less than 7% of low-risk fetuses with hyperechoic bowel will have MI. Contemporary series of noninvasive management with Gastrografin enema report success rates of 36% to 39%, significantly lower than historical values. The optimal surgical technique remains controversial, although primary anastomosis results in surgical complication rates between 21% and 31%, higher than those noted with delayed anastomosis. Pulmonary function for patients with CF and MI at 15 and 25 years old is similar to those without MI, although height and weight percentiles may be lower.

CONCLUSIONS

This review for pediatric surgeons presents an examination of the literature and synthesizes current information about the pathophysiology, prenatal diagnosis, nonoperative and operative management, postoperative management, and prognosis of the patient with CF and MI.