Transient type 1 pseudo-hypoaldosteronism: report on an eight-patient series and literature review

Hyponatremia in babies: a 11-year single-center study

Introduction

Hyponatremia is one of the most prevalent water-electrolyte disturbances encountered in clinical practice in pediatrics and can arise from various conditions. However, there are limited reports on hyponatremia in hospitalized infants. The objective of this study was to provide an overview of the incidence, etiologies, and clinical characteristics of hyponatremia in hospitalized babies (from birth to 3 years old) at a tertiary hospital.

Method

Computer records of all hospitalized babies (from birth to 3 years old) with hyponatremia were extracted from the First Affiliated Hospital of Guangxi Medical University's clinical databases.

Results

801 patients from 39,019 hospital admissions were found to have hyponatremia and the overall prevalence of this condition was 2.05% in babies. Patients with hyponatremia due to aldosterone signaling abnormalities, neurological disorders, and liver diseases exhibited more severe outcomes than those with other etiologies.

Conclusions

Various conditions can result in hyponatremia in hospitalized babies. Aldosterone signaling abnormalities were not that uncommon and it could lead to severe hyponatremia in babies.

Autosomal Dominant Pseudohypoaldosteronism Type 1 in a Newborn With Failure to Thrive

Pseudohypoaldosteronism type 1 is a rare genetic disorder characterized by salt wasting and resistance to mineralocorticoids due to mutations in the NR3C2 gene which codes for the aldosterone receptor proteins in the kidneys. This case study involves an infant who presented with poor growth and significant hyponatremia. There was improvement in growth and correction of hyponatremia with sodium supplementation, later found to carry a new genetic variant causing autosomal dominant pseudohypoaldosteronism type 1. A 14-day-old newborn presented with failure to thrive, severe hyponatremia, mild hyperkalemia, and metabolic acidosis. The electrolyte abnormalities were corrected with intravenous fluid and sodium supplementation. Continued oral sodium supplementation led to improved weight gain. Clinical suspicion and subsequent diagnostic testing led to a diagnosis of the autosomal dominant renal form of pseudohypoaldosteronism type 1. Genetic testing revealed a novel mutation on the NR3C2 gene, c.556_557del (p.Met186Valfs*3). The baby was discharged home on supplemental sodium and high-calorie formula for catch-up growth. Outpatient follow-up is ongoing.

A case of secondary pseudohypoaldosteronism that presented as poor weight gain

Key clinical message

Pseudohypoaldosteronism (PHA) carries a good prognosis if treated early and appropriately, but some cases can have life-threatening events. We underscored the need to consider secondary PHA as one of the differential diagnoses of hyponatremia and hyperkalemia in infancy.

Abstract

Pseudohypoaldosteronism (PHA) type 1 has two classifications; the primary type, caused by genetic abnormalities that develop during neonatal and infancy periods, and the secondary type, caused by urinary tract malformation and urinary tract infection. Secondary PHA, if treated early and appropriately, has a good prognosis; however, some cases can present life-threatening events. Therefore, early diagnosis is crucial. We present a case of early infancy secondary PHA presented with marked hyponatremia and poor weight gain. The patient's growth and development improved with secondary PHA treatment. Here, were demonstrated the value of prompt action against infection and electrolyte imbalance and the importance of imaging for diagnosis, and underscore the need to consider secondary PHA as a differential diagnoses of hyponatremia and hyperkalemia in infancy. However further studies, including basic research, to elucidate the diseases pathology is warranted.

Case report: Life threatening hyponatremia in infants with urinary tract infections: two cases of type III pseudohypoaldosteronism and review of the literature

We describe two female infants at the age of five and six months with urinary tract infections presenting with vomiting and reduced drinking behavior. On laboratory analysis, severe hyponatremia (106 mmol/L and 109 mmol/L) was seen with hyperkalemia and compensated metabolic acidosis. Endocrinological analyses revealed massively increased levels of aldosterone and renin, leading to the diagnosis of type III pseudohypoaldosteronism (PHA). A review of the current literature 2013-2023 revealed 26 type III PHA cases aged up to ten months with reduced drinking behavior, weight loss and/or failure to thrive being the most common clinical presentations. Given the severe presentation of PHA electrolyte measurements in infants with urinary tract infections and/or in infants with congenital anomalies of the kidney and urinary tract (CAKUT) are strongly recommended.

Analysis of patients presenting with serum electrolyte imbalance in terms of the differential diagnosis of pseudohypoaldosteronism

OBJECTIVE

The aim of this study was to contribute to the differential diagnosis of transient pseudohypoaldosteronism (t-PHA).

METHODS

Twenty-nine infants, younger than 24 weeks, and with high aldosterone levels were included in the study. The patients were divided into two groups as t-PHA and other diagnoses group. Of 29 patients, 18 were in the t-PHA group and 11 were in other diagnoses group.

RESULTS

The means aldosterone, plasma renin activities (PRA), adrenocorticotropic hormone (ACTH), cortisol, and 17-hydroxyprogesterone (17-OHP) of those with t-PHA were 138±92.8 ng/dL, 8.39±10.57 ng/mL/h, 26.86±19.56 ng/L, 19.44±21.84 μg/dL, and 7.66±10.71 ng/mL, respectively. In other diagnoses group, the mean level of aldosterone, PRA, ACTH, cortisol, and 17-OHP levels was 100.9±70 ng/dL, 5.49±8.41 ng/mL/h, 408.28±491.9 ng/L, 19.99±14.43 μg/dL, and 11.99±12.21 ng/mL, respectively. In the t-PHA group, the number of patients with high PRA was eight (50%), while the number of patients with high levels was two (18.1%) in other diagnoses group. In the t-PHA group, although the average serum K levels were the same in both groups, serum aldosterone/K ratios were higher.

CONCLUSION

When an infant younger than 24 weeks, with urinary tract infection and/or urinary tract malformation has electrolyte abnormalities, pediatricians should primarily consider the diagnosis of t-PHA. Thus, many unnecessary investigations and inappropriate treatments can be avoided.

Hyponatremia and other potential markers of ultrasound abnormalities after a first febrile urinary tract infection in children

Urinary tract infections are the initial manifestation in 30% of urinary tract malformations. Identifying these patients, who could benefit from a specific treatment, is still challenging. Hyponatremia during urinary tract infection has been proposed as a urinary tract malformation marker. We evaluate the prevalence of hyponatremia during febrile urinary tract infections and its association with subjacent urinary tract malformations. We performed a retrospective study of healthy patients under 16 years, diagnosed with a first episode of febrile urinary tract infection, who had undergone blood testing in the acute episode and at least one renal ultrasound during follow-up (January 2014-November 2020). Hyponatremia was defined as (serum sodium ≤ 130 mEq/L). According to imaging findings, we classified patients into three groups: normal kidney ultrasound, mild pelviectasis, and significant urinary tract malformation. We performed logistic regression models to identify independent risk factors for urinary tract malformation and mild pelviectasis. We included 492 patients and 2.8% presented hyponatremia. We identified normal ultrasound in 77%, mild pelviectasis in 10.8%, and urinary tract malformation in 12% of patients. We found an association between mild pelviectasis and hyponatremia [OR 6.6 (CI95% 1.6-26.6)]. However, we found no association between hyponatremia and urinary tract malformation. The parameters that were associated with malformations were presenting a non-E. coli infection, C-reactive-protein levels over 80 mg/L, and bacteremia.

CONCLUSION

Hyponatremia during the first episode of febrile urinary tract infection is present in 2.8% of patients and is associated with mild pelviectasis in imaging. However, hyponatremia does not indicate a greater need for complementary tests to screen for urinary tract malformations.

WHAT IS KNOWN

• Urinary tract infection is the first manifestation in 30% of children with urinary tract malformation. • Hyponatremia could be a marker to identify these children and guide the imaging approach.

WHAT IS NEW

• Around 12% of children with a first episode of febrile urinary tract infection have a urinary tract malformation. • Non-E. coli infection, C-reactive protein levels over 80 mg/L, and bacteremia are markers for malformations to guide diagnostic imaging tests, but hyponatremia (Na ≤ 130 mEq/l) is not a reliable marker.

Early-in-Life Serum Aldosterone Levels Could Predict Surgery in Patients with Obstructive Congenital Anomalies of the Kidney and Urinary Tract: A Pilot Study

The aim of the study was to evaluate whether serum aldosterone levels or plasmatic renin activity (PRA) measured early in life (1-3 months) could predict a future surgical intervention for obstructive congenital anomalies of kidney and urinary tract (CAKUT). Twenty babies aged 1-3 months of life with suspected obstructive CAKUT were prospectively enrolled. The patients underwent a 2-year follow-up and were classified as patients needing or not needing surgery. In all of the enrolled patients, PRA and serum aldosterone levels were measured at 1-3 months of life and were evaluated as predictors of surgery by receiver-operating characteristic (ROC) curve analysis. Patients undergoing surgery during follow-up showed significantly higher levels of aldosterone at 1-3 months of life compared to those who did not require surgery (p = 0.006). The ROC curve analysis of the aldosterone for obstructive CAKUT needing surgery showed an area under the ROC curve of 0.88 (95%CI = 0.71-0.95; p = 0.001). The aldosterone cut-off of 100 ng/dL presented 100% sensitivity and 64.3% specificity and predicted surgery in 100% of cases. The PRA at 1-3 months of life was not a predictor of surgery. In conclusion, serum aldosterone levels at 1-3 months could predict the need for surgery during obstructive CAKUT follow-up.

A Five-Month-Old Boy With Hypotonia, Electrolyte Derangements, and Failure to Thrive

Failure to thrive in the setting of profound hypotonia and multiple electrolyte derangements is a challenging constellation of findings that offers a broad differential diagnosis for providers to consider. Initial management should focus on the stabilization of the patient and correction of potential life-threatening electrolyte derangements. Once completed, the diagnosis should be sought, and in this case, many were considered and ultimately ruled out with thorough history and physical examination. Laboratory abnormalities revealed the final diagnosis of pseudohypoaldosteronism and connected the case. With proper treatment, our patient had a resolution of laboratory anomalies along with improved growth and tone.

A predictive score for detecting vesicoureteral reflux in children with their first Escherichia coli-induced urinary tract infection

OBJECTIVES

In children with a first Escherichia coli-induced febrile urinary tract infection (fUTI), routine voiding cytourethrography (VCUG) is not recommended for detecting vesicoureteral reflux (VUR). Meanwhile, the sensitivity of renal and bladder ultrasound (RBUS) for detecting VUR is insufficient. Aiming to implement VCUG properly for children with a first E. coli-induced fUTI, we attempted to construct a predictive scoring system for the early screening of VUR.

METHODS

This study enrolled patients aged <2 years of age hospitalized for their first E. coli-induced fUTI during the period when VCUG was implemented for all patients (2007-14, non-selective group [n = 111]) and only for those with VUR-suspected RBUS findings, bacteremia or acute focal bacterial nephritis (2016-19, selective group [n = 102]). We evaluated the accuracy of the current criteria and the VUR predictive score constructed using data from the non-selective group.

RESULTS

In the non-selective group, 32 patients had VUR (29%). In the selective group, 20 of 45 VCUG-tested patients had VUR (44%). Among 57 patients not undergoing VCUG in the selective group, 8 had a recurrence of fUTI, 3 of whom were diagnosed with VUR. In the non-selective group, 9 patients with VUR did not fulfill the current criteria and the VUR predictive score consisting of young age, female sex, prolonged fever, hypoproteinemia, hyponatremia and hyperglycemia, showed higher sensitivity, specificity than the current criteria.

CONCLUSIONS

The current imaging/bacteriological criteria were ineffective in screening for VUR in patients with their first E. coli-induced fUTI. The VUR predictive score can be an accurate indicator for implementing VCUG.

Challenges of Diagnosing Pseudohypoaldosteronism (PHA) in an Infant

Background. Pseudohypoaldosteronism (PHA) is characterized by renal tubular resistance to aldosterone. As a result, the symptoms typically involve hyperkalemia and hyponatremia. The aim of this clinical case report is to highlight the severe electrolyte imbalance PHA can present within an infant, as well as difficulties in diagnosing the condition. Case Presentation. A 5-week-old male arrived at the ER with episodes of emesis, lethargy, and difficulty in feeding. He had significant electrolyte abnormalities and was being treated by his PCP for failure to thrive. He presented with urinary sodium wasting, indicated by hyponatremia, hyperkalemia, low chloride, and hypercalcemia. Patient was treated with IVF and NaCl supplementation to normalize the electrolytes. The patient showed heterozygosity for a variant in the WNK1 gene, which typically causes Gordon syndrome; however, our patient had a normal blood pressure. The electrolyte imbalance self-resolved during several months of follow-up, and currently, the patient is not on any treatment.

The invention of aldosterone, how the past resurfaces in pediatric endocrinology

Sodium and water homeostasis are drastically modified at birth, in mammals, by the transition from aquatic life to terrestrial life. Accumulating evidence during the past ten years underscores the central role for the mineralocorticoid signaling pathway, in the fine regulation of this equilibrium, at this critical period of development. Interestingly, regarding evolution, while the mineralocorticoid receptor is expressed in fish, the appearance of its related ligand, aldosterone, coincides with terrestrial life, as it is first detected in lungfish and amphibian. Thus, aldosterone is likely one of the main hormones regulating the transition from an aquatic environment to an air environment. This review will focus on the different actors of the mineralocorticoid signaling pathway from aldosterone secretion in the adrenal gland, to mineralocorticoid receptor expression in the kidney, summarizing their regulation and roles throughout fetal and neonatal development, in the light of evolution.

Sexual Dimorphism of Corticosteroid Signaling during Kidney Development

Sexual dimorphism involves differences between biological sexes that go beyond sexual characteristics. In mammals, differences between sexes have been demonstrated regarding various biological processes, including blood pressure and predisposition to develop hypertension early in adulthood, which may rely on early events during development and in the neonatal period. Recent studies suggest that corticosteroid signaling pathways (comprising glucocorticoid and mineralocorticoid signaling pathways) have distinct tissue-specific expression and regulation during this specific temporal window in a sex-dependent manner, most notably in the kidney. This review outlines the evidence for a gender differential expression and activation of renal corticosteroid signaling pathways in the mammalian fetus and neonate, from mouse to human, that may favor mineralocorticoid signaling in females and glucocorticoid signaling in males. Determining the effects of such differences may shed light on short term and long term pathophysiological consequences, markedly for males.

Transient Pseudohypoaldosteronism Secondary to Group B Streptococcus Pyelonephritis

Secondary pseudohypoaldosteronism is a condition characterized by aldosterone resistance in renal tubules. It is highly associated with urinary tract infection and urinary tract malformations. Only a few cases of pseudohypoaldosteronism secondary to group B Streptococcus pyelonephritis have been reported to date. A four-month-old boy developed poor sucking and weight loss, and his laboratory test results revealed hyponatremia, hyperkalemia, renal dysfunction, high anion gap metabolic acidosis, pyuria, and hydronephrosis. Laboratory tests including urinalysis confirmed the diagnosis of pseudohypoaldosteronism secondary to group B Streptococcus. He was treated with intravenous normal saline and antimicrobial therapy. Electrolyte disorders were addressed and he was discharged on the 10th day of hospitalization without any sequelae. Voiding cystourethrography performed after discharge showed bilateral grade 5 vesicoureteral reflux and intrarenal reflux in the right kidney. Transient pseudohypoaldosteronism is an important consideration in the differential diagnosis in infants with hyponatremia and hyperkalemia. A thorough evaluation for urinary tract malformations should be performed, including early abdominal ultrasonography and systemic management.

The incidence of transient infantile pseudohypoaldosteronism in Ireland: A prospective study

AIM

To review the clinical course, outcome and incidence of infantile salt wasting associated with urinary tract infection (UTI) and/or urinary tract malformation (UTM) over a two-year surveillance period on the island of Ireland.

METHODS

A two-year (2013-14) prospective surveillance undertaken via the Irish and Ulster Paediatric Surveillance Units. Monthly prepaid postcards were circulated to consultant paediatricians (n = 260) at all paediatric units on the island of Ireland. Infants under one year of age presenting for the first time with hyponatraemia (Na < 130 mmol/L) and/or hyperkalaemia (K > 5.0 mmol/L) associated with urosepsis/UTM were reported.

RESULTS

All 7 reported patients (6 male) had culture-proven UTI, and 5 (71%) also had an underlying UTM (one diagnosed antenatally). Four (57%) patients had a documented elevated serum aldosterone supporting secondary pseudohypoaldosteronism (PHA) as the underlying diagnosis. Data on aldosterone were not reported in the other 3 patients, but clinical features were suggestive of secondary PHA. The estimated incidence for the Irish population of transient PHA is 1 per 13,200 total live births per year.

CONCLUSIONS

Salt wasting is a rare complication of UTI, especially if associated with underlying UTM. Boys appear to be at particular risk.

Hyponatremia in childhood urinary tract infection

Acute urinary tract infection (UTI) is the most common bacterial infection in childhood. Although hyponatremia was described in ~ 2/3 of these children, its clinical significance is still unclear. Herein, we evaluated the prevalence and clinical implications of hyponatremia in children hospitalized with a UTI. Medical records of previously healthy children hospitalized between January 2011 and December 2016 with UTI were retrospectively reviewed. Patients (median age 5.5 months) were divided into two groups according to their sodium levels: normonatremia (Na ≥ 135 mEq/L) and hyponatremia (Na < 135 mEq/L). Hyponatremia diagnosed on admission was found in 114/219 children (49%). Hyponatremic patients experienced a more severe disease manifested by a longer hospital stay (3.8 vs 3.4 days, p = 0.003), a higher prevalence of abnormal findings on renal ultrasound (10 vs 2, p = 0.01), higher C-reactive protein (CRP) levels (8.6 vs 3.4 mg/dl, p = <0.001), and a negative correlation between sodium levels and CRP (r = - 0.38, p < 0.001).Conclusion:Hyponatremia occurs frequently in children hospitalized with UTI and is associated with elevated inflammatory markers and a more severe disease course. What is Known: • Hyponatremia, one of the most common electrolyte abnormalities, occurs in approximately 1/3 of hospitalized children and in 2/3 of children with pyelonephritis. • In certain cases of various medical conditions, hyponatremia has been shown to correlate with disease severity. What is New: • Hyponatremia in hospitalized children with UTI correlates with elevated inflammatory markers and a more severe disease course.

Secondary Pseudohypoaldosteronism Associated With Mild Hydronephrosis in a Newborn

Neonatal hyponatremia with hyperkalemia is a rare but potentially life-threatening occurrence. Aldosterone deficiency secondary to congenital adrenal hyperplasia (CAH) is often suspected in these cases, although it is not easy to accurately diagnose it initially. We report the case of a 12-day-old female infant presenting with poor sucking, hyperkalemia, and hyponatremia. Plasma renin activity (PRA) and aldosterone levels were markedly elevated, and mild hydronephrosis [Society for Fetal Urology (SFU) grade 1] was noted. We then suspected secondary pseudohypoaldosteronism (S-PHA); however, her serum potassium level remained elevated despite sodium infusion. Because we could not rule out a diagnosis of adrenal insufficiency caused by CAH, we cautiously initiated hydrocortisone. After reviewing the results of a mass screening test and a urine steroid profile analysis, adrenal diseases were ruled out and we diagnosed the patient with S-PHA. This report aims to illustrate that mild hydronephrosis can cause S-PHA by inducing renal tubular resistance to aldosterone. Because the symptoms of S-PHA are similar to those of CAH, we recognize that further studies are needed to clarify their differences.

A rare cause of salt-wasting in early infancy: Transient pseudohypoaldosteronism

Three infants aged between 38 days and 43 days all presented with poor weight gain, hyponatremia, hyperkalemia, and were diagnosed as having urinary tract infections, which were accompanied by urinary tract malformations in our cases. Hydration and infection treatments were given. A few days after admission, hormonal studies revealed normal cortisol and 17-hydroxy progesterone levels and markedly high aldosterone levels, thus the patients were diagnosed as having transient pseudohypoaldosteronism. After the proper treatment was given, the transient pseudohypoaldosteronism resolved. In conclusion, when an infant with urinary tract infection or malformation has electrolyte abnormalities, pediatricians should consider the diagnosis of transient pseudohypoaldosteronism.

Clinical features, genetic background, and outcome in infants with urinary tract infection and type IV renal tubular acidosis

BACKGROUND

Type IV renal tubular acidosis (RTA) is a severe complication of urinary tract infection (UTI) in infants. A detailed clinical and molecular analysis is still lacking.

METHODS

Infants with UTI who exhibited features of type IV RTA were prospectively enrolled. Clinical, laboratory, and image characteristics and sequencing of genes responsible for phenotype were determined with follow-up.

RESULTS

The study cohort included 12 infants (9 males, age 1-8 months). All exhibited typical type IV RTA such as hyperkalemia with low transtubular potassium gradient, hyperchloremic metabolic acidosis with positive urine anion gap, hypovolemic hyponatremia with renal salt wasting, and high plasma renin and aldosterone levels. Seven had hyperkalemia-related arrhythmia and two of them developed life-threatening ventricular tachycardia. With prompt therapy, all clinical and biochemical abnormalities resolved within 1 week. Five had normal urinary tract anatomy, and three of them carried genetic variants on NR3C2. Three variants, c.1645T>G (S549A), c.538G>A (V180I), and c.1-2C>G, on NR3C2 were identified in four patients. During follow-up, none of them had recurrent type IV RTA, but four developed renal scaring.

CONCLUSIONS

Genetic mutation on NR3C2 may contribute to the development of type IV RTA as a complication of UTI in infants without identifiable risk factors, such as urinary tract anomalies.

Phenotypic diversity and correlation with the genotypes of pseudohypoaldosteronism type 1

Background Type I pseudohypoaldosteronism (PHA1) is a rare condition characterised by profound salt wasting, hyperkalaemia and metabolic acidosis due to renal tubular resistance to aldosterone (PHA1a) or defective sodium epithelial channels (PHA1b or systemic PHA). Our aim was to review the clinical presentation related to the genotype in patients with PHA1. Methods A questionnaire-based cross-sectional survey was undertaken through the British Society of Paediatric Endocrinology and Diabetes (BSPED) examining the clinical presentation and management of patients with genetically confirmed PHA1. We also reviewed previously reported patients where genotypic and phenotypic information were reported. Results Genetic confirmation was made in 12 patients with PHA1; four had PHA1a, including one novel mutation in NR3C2; eight had PHA1b, including three with novel mutations in SCNN1A and one novel mutation in SCNN1B. It was impossible to differentiate between types of PHA1 from early clinical presentation or the biochemical and hormonal profile. Patients presenting with missense mutations of SCNN1A and SCNN1B had a less marked rise in serum aldosterone suggesting preservation in sodium epithelial channel function. Conclusions We advocate early genetic testing in patients with presumed PHA1, given the challenges in differentiating between patients with PHA1a and PHA1b. Clinical course differs between patients with NR3C2 and SCNN1A mutations with a poorer prognosis in those with multisystem PHA. There were no obvious genotype-phenotype correlations between mutations on the same gene in our cohort and others, although a lower serum aldosterone may suggest a missense mutation in SCNN1 in patients with PHA1b.

Transient pseudohypoaldosteronism: a potentially severe condition affecting infants with urinary tract malformation

BACKGROUND

Secondary pseudohypoaldosteronism (S-PHA) is a life-threatening condition affecting young children with urinary tract malformation (UTM).

OBJECTIVE

The aim of the study was to highlight the diagnosis of S-PHA in children with UTM and propose appropriate management.

STUDY DESIGN

The authors retrospectively reviewed cases of S-PHA related to UTM observed at the institution and searched the PubMed® database to review the literature.

RESULTS

A total of 116 cases of S-PHA associated with UTM, including the four cases from the institution, were reviewed. One hundred six cases (92.2%) were younger than 6 months, and 95 cases (81.9%) occurred in boys. Urinary tract infection was associated in 105 cases (90.5%). All types of UTM were observed. In the absence of urinary tract infection, S-PHA was related to bilateral UTM or solitary kidney. In 89 cases (76.5%), S-PHA resolved with medical treatment only. In cases of UTM requiring immediate surgery, electrolyte imbalance related to S-PHA also resolved after surgery. Children with associated urinary tract infection and bilateral UTM are at higher risk of developing S-PHA.

DISCUSSION

The pathogenesis of S-PHA has not been fully elucidated. Renal tubular immaturity may be one of the factors involved, in view of the young age of the population being affected. A high rate of bilateral UTM (or UTM on solitary kidney) was observed (50.9%), suggesting an association with S-PHA. In the absence of urinary tract infection (UTI), S-PHA appeared to occur more frequently in the presence of bilateral UTM. Although the indication for early surgery remains unclear, it may have a role in the prevention of UTI and prevention of recurrence of S-PHA. Serum electrolytes should be checked in children with UTM before urological surgery, and/or presenting urinary tract infection, before the age of 6 months. The results of this study must be interpreted cautiously because of its retrospective nature and the fact that data were derived from various articles. Few articles on S-PHA related to UTM have been published in the literature. To the best of the authors' knowledge, the study constitutes the largest series published to date.

CONCLUSIONS

S-PHA results in potentially severe electrolyte imbalance and affects children younger than 6 months with UTI and/or UTM. Electrolyte abnormalities related to S-PHA often resolve after administration of appropriate intravenous electrolyte solution and treatment of UTI and/or surgery.

An infant presenting with failure to thrive and hyperkalaemia owing to transient pseudohypoaldosteronism: case report

A 3-month-old boy presented with failure to thrive and a history of a prenatally detected unilateral hydroureteronephrosis which was confirmed after birth. His growth and developmental milestones had been normal during the first 2 months but in the third month his appetite was poor with reduced intake but no vomiting. At presentation, his temperature was normal, there was mild dehydration and there was weight loss (his weight had decreased by 270 g in the past month). Haemoglobin was 11.9 g/dL, total white cell count 20.2 × 10⁹/L (7-15) [neutrophils 30% (39-75) and lymphocytes 61% (16-47)], platelets 702 × 10⁹/L (150-450), BUN12.1 mmol/L (2.1-16.1), serum creatinine 35.4 μmol/L (15.0-37.1), sodium 126 mmol/L (135-144), potassium 6.8 mmol/L (3.6-4.8), chloride 88 mmol/L (98-106) and bicarbonate 14 mmol/L (19-24). Intravenous rehydration with sodium chloride 0.9% solution was commenced and he was transferred to the paediatric intensive care unit. A salt-wasting syndrome was suspected and a differential diagnosis included adrenal insufficiency, pseudohypoaldosteronism and congenital adrenal hyperplasia (owing to 21-hydroxylase deficiency). Urinalysis confirmed a urinary tract infection. Serum aldosterone was 3608 ng/dL (3.7-43.2), plasma renin activity > 38.9 pmol/L (<0.85), random cortisol 459 nmol/L (74-289), adrenocorticotropic hormone (ACTH) 6.01 pmol/L (1.32-6.60) and 17-hydroxyprogesterone 4.01 nmol/L (<3.2). Treatment of the urinary tract infection was followed by normalisation of serum electrolytes and other biochemical abnormalities, return of appetite and normal growth, which confirmed the diagnosis of transient pseudohypoaldosteronsim (TPHA). TPHA is discussed and insight provided to enable early recognition and adequate treatment of this rare clinical entity.

Epigenetic Regulation of Adipokines

Adipose tissue expansion in obesity leads to changes in the expression of adipokines, adipocyte-specific hormones that can regulate whole body energy metabolism. Epigenetic regulation of gene expression is a mechanism by which cells can alter gene expression through the modifications of DNA and histones. Epigenetic mechanisms, such as DNA methylation and histone modifications, are intimately tied to energy metabolism due to their dependence on metabolic intermediates such as S-adenosylmethionine and acetyl-CoA. Altered expression of adipokines in obesity may be due to epigenetic changes. The goal of this review is to highlight current knowledge of epigenetic regulation of adipokines.

Clinical features and molecular basis of pseudohypoaldosteronism type 1

Pseudohypoaldosteronism (PHA) type 1 is a disease showing mineralocorticoid resistance in the kidney and/or other mineralocorticoid target tissues. Patients with PHA1 present very high plasma aldosterone and renin levels, but they develop excessive salt wasting. There are three types of PHA1. The systemic form of PHA1 is inherited in an autosomal recessive manner and causes severe life-long salt loss in multiple target tissues, such as sweat glands, salivary glands, the colonic epithelium, and the lung. In the systemic form of PHA1, life-long salt supplementation is necessary. The second type is the renal form, where aldosterone resistance is shown only in the kidney, and its inheritance is autosomal dominant. In the renal form of PHA1, salt supplementation generally becomes unnecessary by 1-3 yr of age. The third type is the secondary PHA1, which is strongly associated with urinary tract infections and/or urinary tract malformations. This review summarizes the clinical features and molecular basis of PHA1. Understanding of its pathogenesis can be helpful for the early diagnosis and clinical care of affected children with PHA1.

Transient Fanconi syndrome in two preterm infants with hydronephrosis and urinary tract infection

Type IV renal tubular acidosis is known to occur in obstructive uropathy with urinary tract infection. Fanconi syndrome, however, has not been described in these settings. We report two preterm infants who developed Fanconi syndrome associated with hydronephrosis and urinary tract infection. Patient 1 is a boy with 21 trisomy, bilateral renal hypoplasia and bilateral vesicoureteral reflux delivered at 35 weeks' gestation. At postnatal day 42, he developed Fanconi syndrome after urinary tract infection, which persisted until the surgical correction of vesicoureteral reflux. Patient 2 was delivered at 35 weeks' gestation. At postnatal day 9, he was admitted for severe dehydration. He had phimosis and ultrasonography showed left pelviectasis. Laboratory data were compatible with Fanconi syndrome, which resolved spontaneously after fluid therapy. Subsequently urine culture grew bacteria and treatment for infection and topical corticosteroid for phimosis were performed. DMSA scintigraphy performed later showed left renal scar. Tubular cell stretch, due to vesicoureteral reflux in Patient 1 and phimosis in Patient 2, and urinary tract infection in association with immaturity of tubules are thought to have caused Fanconi syndrome.

Transient pseudohypoaldosteronism in infancy secondary to urinary tract infection

AIM

Hyponatraemia with hyperkalaemia in infancy is a typical presentation of congenital adrenal hyperplasia. In the presence of pyelonephritis, the same biochemical picture can occur with transient type 1 pseudohypoaldosteronism (PHA-1) also termed type 4 renal tubular acidosis. Recognition of PHA-1 enables appropriate management thus avoiding unnecessary investigations and treatment. To improve awareness of this condition, we present a case series to highlight the clinical and biochemical features of PHA-1.

METHODS

A retrospective chart review of patients diagnosed with transient PHA-1 at a tertiary children's hospital in Western Australia was conducted.

RESULTS

Five male infants (32 days to 6 months) with transient PHA-1 were identified. Failure to thrive was the most common symptom with hyponatraemia on presentation. Two infants had antenatally diagnosed bilateral hydronephrosis and urinary tract infection (UTI) on admission. Two infants were treated for congenital adrenal hyperplasia and received hydrocortisone. All infants had UTI and required parenteral antibiotics. The condition was transient and hyponatraemia corrected by day 4 in all infants. There was no correlation between plasma sodium and aldosterone levels. The severity of PHA-1 was independent of the underlying renal anomaly. Four infants had hydronephrosis and vesicoureteric reflux. Surgical intervention was required in two infants.

CONCLUSIONS

PHA-1 may be precipitated by UTI or urinary tract anomalies in early infancy. Urine analysis should be performed in infants with hyponatraemia. Diagnosis of PHA-1 facilitates appropriate renal investigations to reduce long-term morbidity.

Systemic Pseudohypoaldosteronism Type I: A Case Report and Review of the Literature

Systemic pseudohypoaldosteronism (PHA) type I is a rare genetic disorder resulting from mutations in the subunits of the epithelial sodium channel that manifests as severe salt wasting, hyperkalemia, and metabolic acidosis in infancy. In this article we report a patient with systemic PHA type I presenting with severe dehydration due to salt wasting at 6 days of life. She was found to have a known mutation in the SCNN1A gene and subsequently required treatment with sodium supplementation. We also review the clinical presentation, differential diagnosis, and treatment of systemic PHA type I and summarize data from 27 cases with follow-up data.

Water Balance and 'Salt Wasting' in the First Year of Life: The Role of Aldosterone-Signaling Defects

In newborns and infants, dehydration and salt wasting represent a relatively common cause of admission to hospital and may result in life-threatening complications. Kidneys are responsible for electrolyte homoeostasis, but neonatal kidneys show low glomerular filtration rate and immaturity of the distal nephron, leading to reduced ability to concentrate urine. High extrarenal fluid losses often contribute to the increased occurrence of electrolyte disorders. Aldosterone is essential for sodium retention in the kidney, salivary glands, sweat glands and colon. A partial and transient aldosterone resistance is present in newborns and infants, thus reducing the capability of maintaining sodium balance in specific pathological conditions. The present review examines the mechanisms making infants more susceptible to salt wasting. Peculiar aspects of renal physiology in the first year of life and management of electrolyte disorders (i.e. sodium and potassium) are considered. Finally, inherited disorders associated with neonatal salt wasting are examined in detail. © 2016 S. Karger AG, Basel.

Na(+), K(+), Cl(-), acid-base or H2O homeostasis in children with urinary tract infections: a narrative review

Guidelines on the diagnosis and management of urinary tract infections in childhood do not address the issue of abnormalities in Na(+), K(+), Cl(-) and acid-base balance. We have conducted a narrative review of the literature with the aim to describe the underlying mechanisms of these abnormalities and to suggest therapeutic maneuvers. Abnormalities in Na(+), K(+), Cl(-) and acid-base balance are common in newborns and infants and uncommon in children of more than 3 years of age. Such abnormalities may result from factitious laboratory results, from signs and symptoms (such as excessive sweating, poor fluid intake, vomiting and passage of loose stools) of the infection itself, from a renal dysfunction, from improper parenteral fluid management or from the prescribed antimicrobials. In addition, two transient renal tubular dysfunctions may occur in infants with infectious renal parenchymal involvement: a reduced capacity to concentrate urine and pseudohypoaldosteronism secondary to renal tubular unresponsiveness to aldosterone that presents with hyponatremia, hyperkalemia and acidosis. In addition to antimicrobials, volume resuscitation with an isotonic solution is required in these children. In secondary pseudohypoaldosteronism, isotonic solutions (such as 0.9 % saline or lactated Ringer) correct not only the volume depletion but also the hyperkalemia and acidosis. In conclusion, our review suggests that in infants with infectious renal parenchymal involvement, non-renal and renal causes concur to cause fluid volume depletion and abnormalities in electrolyte and acid-base balance, most frequently hyponatremia.

Hyponatremia in the intensive care unit: How to avoid a Zugzwang situation?

Hyponatremia is a common electrolyte derangement in the setting of the intensive care unit. Life-threatening neurological complications may arise not only in case of a severe (<120 mmol/L) and acute fall of plasma sodium levels, but may also stem from overly rapid correction of hyponatremia. Additionally, even mild hyponatremia carries a poor short-term and long-term prognosis across a wide range of conditions. Its multifaceted and intricate physiopathology may seem deterring at first glance, yet a careful multi-step diagnostic approach may easily unravel the underlying mechanisms and enable physicians to adopt the adequate measures at the patient’s bedside. Unless hyponatremia is associated with obvious extracellular fluid volume increase such as in heart failure or cirrhosis, hypertonic saline therapy is the cornerstone of the therapeutic of profound or severely symptomatic hyponatremia. When overcorrection of hyponatremia occurs, recent data indicate that re-lowering of plasma sodium levels through the infusion of hypotonic fluids and the cautious use of desmopressin acetate represent a reasonable strategy. New therapeutic options have recently emerged, foremost among these being vaptans, but their use in the setting of the intensive care unit remains to be clarified.

Secondary pseudohypoaldosteronism causing cardiopulmonary arrest and cholelithiasis

A 4-month-old boy presented with cardiopulmonary arrest on arrival after a brief period of lethargy. Laboratory examination indicated severe hyperkalemia, hyponatremia, metabolic acidosis, and slightly elevated C-reactive protein. Whole body computed tomography identified left-dominant hydronephrosis, hydroureter and cholelithiasis. Despite cardiac arrest >30 min, he was successfully resuscitated and treated with therapeutic hypothermia. Escherichia coli was detected on urine culture. Renal ultrasound showed bilateral hydronephrosis, grade II in the right and grade IV in the left. Retrospective analysis of the blood sample at admission indicated a high level of aldosterone. The patient recovered almost fully with no electrolyte imbalance and normal plasma renin and aldosterone, leading to the diagnosis of secondary pseudohypoaldosteronism associated with bilateral infected hydronephrosis. In this case, cholelithiasis, which may account for chronic dehydration, was a diagnostic clue in the absence of information of pre-existing situations.

Autosomal dominant pseudohypoaldosteronism type 1 in an infant with salt wasting crisis associated with urinary tract infection and obstructive uropathy

Type 1 pseudohypoaldosteronism (PHA1) is a salt wasting syndrome caused by renal resistance to aldosterone. Primary renal PHA1 or autosomal dominant PHA1 is caused by mutations in mineralocorticoids receptor gene (NR3C2), while secondary PHA1 is frequently associated with urinary tract infection (UTI) and/or urinary tract malformations (UTM). We report a 14-day-old male infant presenting with severe hyperkalemia, hyponatremic dehydration, metabolic acidosis, and markedly elevated serum aldosterone level, initially thought to have secondary PHA1 due to the associated UTI and posterior urethral valves. His serum aldosterone remained elevated at 5 months of age, despite resolution of salt wasting symptoms. Chromosomal microarray analysis revealed a deletion of exons 3-5 in NR3C2 in the patient and his asymptomatic mother who also had elevated serum aldosterone level, confirming that he had primary or autosomal dominant PHA1. Our case raises the possibility that some patients with secondary PHA1 attributed to UTI and/or UTM may instead have primary autosomal dominant PHA1, for which genetic testing should be considered to identify the cause, determine future recurrence risk, and possibly prevent the life-threatening salt wasting in a subsequent family member. Future clinical research is needed to investigate the potential overlapping between secondary PHA1 and primary autosomal dominant PHA1.

Electrolyte disturbances in acute pyelonephritis

The aim of this study was to determine whether renal unresponsiveness to aldosterone associated with hyperkalemia is present in infants with acute pyelonephritis in the absence of significant urinary tract anomalies and to describe the clinical characteristics of patients presenting an inadequate renal response to hyperkalemia. The patient cohort comprised 113 infants with acute pyelonephritis (APN), based on the criteria of a temperature >38°C and significant bacteriuria. Serum and urine electrolytes, creatinine, osmolality, and renal tubular function tests were performed at diagnosis. The findings were compared to those present in 75 children who had fever without significant bacteriuria. Hyperkalemia (>5.5 mmol/L) was observed in infants with an APN diagnosis, who exhibited a lower transtubular potassium concentration gradient (TTKG) and a higher fractional sodium excretion. We defined inadequate renal response to hyperkalemia as the combination of hyperkalemia and TTKG below the normal range established for the age of the subject. Infants presenting an inadequate response to hyperkalemia were younger and associated more frequently with an APN diagnosis. This alteration could be explained by the renal interstitial inflammation present in acute pyelonephritis and the immaturity of the renal tubular responsiveness to aldosterone due to infancy in the absence of urinary tract infection or obstruction.

Salt-losing crisis in infants-not always of adrenal origin

Three infants (age 1.5, 4 and 7 months) presented with vomiting, hyponatremia and hyperkalaemia suggestive of a salt-losing congenital adrenal condition. Diagnostic endocrine bloods were taken and adrenal steroid therapy was started. The infants were subsequently found to have raised plasma aldosterone and renin levels due to pyelonephritis and structural anomalies of the kidneys, demonstrating secondary aldosterone resistance.

CONCLUSION

Establishing the diagnosis of congenital adrenal disorders is essential in a baby who develops a salt-losing crisis in the first few weeks of life. However, pyelonephritis should be considered and can be rapidly excluded in any infant presenting with a salt-losing crisis with hyponatremia and hyperkalaemia, in particular, outside the neonatal period. Only then should an endocrine cause for this presentation be considered and treatment commenced.

Syndromes of impaired ion handling in the distal nephron: pseudohypoaldosteronism and familial hyperkalemic hypertension

The distal nephron, which is the site of the micro-regulation of water absorption and ion handling in the kidneys, is under the control of aldosterone. Impairment of the mineralocorticoid signal transduction pathway results in resistance to the action of aldosterone and of mineralocorticoids in general. Herein, we review two syndromes in which ion handling in the distal nephron is impaired: pseudohypoaldosteronism (PHA) and familial hyperkalemic hypertension (FHH). PHA is a rare inherited syndrome characterized by mineralocorticoid resistance, which leads to salt loss, hypotension, hyperkalemia and metabolic acidosis. There are two types of this syndrome: a renal (autosomal dominant) type due to mutations of the mineralocorticoid receptor (MR), and a systemic (autosomal recessive) type due to mutations of the epithelial sodium channel (ENaC). There is also a transient form of PHA, which may be due to urinary tract infections, obstructive uropathy or several medications. FHH is a rare autosomal dominant syndrome, characterized by salt retention, hypertension, hyperkalemia and metabolic acidosis. In FHH, mutations of WNK (with-no-lysine kinase) 4 and 1 alter the activity of several ion transportation systems in the distal nephron. The study of the pathophysiology of PHA and FHH greatly elucidated our understanding of the renin-angiotensin-aldosterone system function and ion handling in the distal nephron. The physiological role of the distal nephron and the pathophysiology of diseases in which the renal tubule is implicated may hence be better understood and, based on this understanding, new drugs can be developed.

Pseudohypoaldosteronism masquerading as congenital adrenal hyperplasia

A 15-day- old male infant presented with features suggestive of congenital adrenal hyperplasia (CAH). But on detailed investigation, he had normal 17-OH Progesterone and high aldosterone levels. Infant also had right sided hydronephrosis and associated urinary tract infection. Hence, a diagnosis of secondary pseudohypoaldosteronism was made. There was good response to sodium chloride supplementation and he was thriving well on follow up. While evaluating any infant with suspected CAH, one should consider secondary pseudohypoaldosteronism, especially when risk factors like urinary tract obstruction or UTI coexists.

Endocrine disorders: causes of hyponatremia not to neglect

Hyponatremia is a common electrolyte abnormality with the potential for significant morbidity and mortality. Endocrine disorders, including adrenal deficiency and hypothyroidism, are uncommon causes of hyponatremia. Primary adrenal insufficiency (i.e. Addison's disease) may well be recognized by clear hall-marks of the disease, such as pigmentation, salt craving, hypotension, and concomitant hyperkalemia. Addison's disease is an important diagnosis not to be missed since the consequences can be grave. On the other hand, hypothyroidism and secondary adrenocortical insufficiency originating from diseases of the hypothalamus and/or pituitary (hypopituitarism) require a high index of suspicion, because the clinical signs can be quite subtle. This review focuses on clinical and pathophysiological aspects of hyponatremia due to endocrine disorders.

Pathogenesis, diagnosis and management of hyperkalemia

Hyperkalemia is a potentially life-threatening condition in which serum potassium exceeds 5.5 mmol/l. It can be caused by reduced renal excretion, excessive intake or leakage of potassium from the intracellular space. In addition to acute and chronic renal failure, hypoaldosteronism, and massive tissue breakdown as in rhabdomyolysis, are typical conditions leading to hyperkalemia. Symptoms are non-specific and predominantly related to muscular or cardiac dysfunction. Treatment has to be initiated immediately using different therapeutic strategies to increase potassium shift into the intracellular space or to increase elimination, together with reduction of intake. Knowledge of the physiological mechanisms of potassium handling is essential in understanding the causes of hyperkalemia as well as its treatment. This article reviews the pathomechanisms leading to hyperkalemic states, its symptoms, and different treatment options.