Salt losing nephropathy simulating congenital adrenal hyperplasia in infants with obstructive uropathy and/or vesicoureteral reflux--value of ultrasonography in diagnosis

Severe hospital-acquired hyponatremia in acutely ill children receiving moderately hypotonic fluids

BACKGROUND

Hypotonic fluids have been associated with hospital-acquired hyponatremia. The incidence of life-threatening severe hyponatremia associated with hypotonic fluids has not been evaluated.

METHODS

This was a population-based cohort study of 46,518 acutely ill children 15 years of age or under who visited the pediatric emergency department (ED) at Oulu University Hospital, Finland, between 2007 and 2017. We retrieved all electrolyte measurements from the comprehensive electronic laboratory system and reviewed medical records for all patients with severe hyponatremia.

RESULTS

The overall occurrence of severe hyponatremia (serum sodium < 125 mmol/L) was found in 27 out of 46,518 acutely ill children (0.06%, 95% confidence interval 0.04-0.08%). After admission, severe hyponatremia developed in seven of 6,984 children receiving moderately hypotonic fluid therapy (0.1%, 95% confidence interval 0.04-0.2%), usually within 8 h of admission. All children who developed severe hyponatremia during hospitalization were severely ill.

CONCLUSION

In this register-based cohort study of children presenting to the ED, severe hyponatremia developed in one of 998 acutely ill children receiving moderately hypotonic fluid therapy. A higher resolution version of the Graphical abstract is available as Supplementary information.

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.

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.

Renal and Adrenal Ultrasonography: a valuable diagnostic tool in the salt-wasting infant

The major differential diagnosis in 'salt-wasting' infants (characterised by hyponatraemia and hyperkalaemia) is that of an adrenal or renal disorder. Appropriate management relies on rapid diagnosis, but existing guidelines do not highlight the role of ultrasonography. We describe how ultrasound may lead to a more rapid diagnosis in disorders of sex development (DSD) and other potential 'salt-wasting' infants.

CONCLUSION

Ultrasonography as a diagnostic tool in infants with salt-wasting or DSD needs to be more widely recognised.

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.

Does pseudohypoaldosteronism mask the diagnosis of congenital adrenal hyperplasia?

Hyponatremia and hyperpotassemia occurring in the first few weeks of life primarily indicate aldosterone deficiency due to salt-losing congenital adrenal hyperplasia (SL-CAH), while mineralocorticoid deficiency and insensitivity are the main causes of hyponatremia and hyperpotassemia in older infants. Some patients who present with vomiting and poor sucking, who have hyponatremia and hyperpotassemia and are initially diagnosed as CAH, during follow-up, are found to suffer from pseudohypoaldosteronism (PHA). This situation has been reported several times before. The cases described here represent the opposite situation: they presented with hyponatremia and hyperpotassemia, thus PHA was considered as aldosterone levels were very high, but subsequent investigation and genetic analysis led to the diagnosis of SL-CAH.

Salt losing obstructive uropathy with paradoxically low urinary sodium concentration: salt entrapment in an obstructed ectopic ureterocele

A 6-month-old hyponatremic female with failure to thrive had low urinary sodium concentration. Renal sonography revealed a duplex left collecting system with obstruction of the upper moiety as a blind-ended ectopic ureterocele extending to the bladder base. The echogenicity of the urine within the upper pole system was greater than the bladder contents. We believed that low urinary sodium concentration represented a false negative test and the salt loss by the obstructed left kidney was entrapped in the upper pole collecting system. Prior to ureterocele repair, intraoperative bladder and ureterocele aspirates revealed discordant sodium concentration supporting the sonographic conclusion.

Transient pseudohypoaldosteronism

Introduction. Infants with urinary tract malformations (UTM) presenting with urinary tract infection (UTI) are prone to develop transient type 1 pseudohypoaldosteronism (THPA1). Objective. Report on patient series with characteristics of THPA1, UTM and/or UTI and suggestions for the diagnosis and therapy. Methods. Patients underwent blood and urine electrolyte and acid-base analysis, serum aldosterosterone levels and plasma rennin activity measuring; urinalysis, urinoculture and renal ultrasound were done and medical and/or surgical therapy was instituted. Results. Hyponatraemia (120.9?5.8 mmol/L), hyperkalaemia (6.9?0.9 mmol/L), metabolic acidosis (plasma bicarbonate, 11?1.4 mmol/L), and a rise in serum creatinine levels (145?101 ?mol/L) were associated with inappropriately high urinary sodium (51.3?17.5 mmol/L) and low potassium (14.1?5.9 mmol/L) excretion. Elevated plasma aldosterone concentrations (170.4?100.5 ng/dL) and the very high levels of the plasma aldosterone to potassium ratio (25.2?15.6) together with diminished urinary K/Na values (0.31?0.19) indicated tubular resistance to aldosterone. After institution of appropriate medical and/or surgical therapy, serum electrolytes, creatinine, and acid-base balance were normalized. Imaging studies showed ureteropyelic or ureterovesical junction obstruction in 3 and 2 patients, respectively, posterior urethral valves in 3, and normal UT in 1 patient. According to our knowledge, this is the first report on THPA1 in the Serbian literature. Conclusion. Male infants with hyponatraemia, hyperkalaemia and metabolic acidosis have to have their urine examined and the renal ultrasound has to be done in order to avoid both, the underdiagnosis of THPA1 and the inappropriate medication.

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

Eight boys aged 2-12 weeks with urinary tract malformations (UTMs) exhibited features of transient type 1 pseudo-hypoaldosteronism (TPHA1) in the course of urinary tract infection (UTI). Hyponatremia (120.9+/-5.8 mmol/l), hyperkalemia (6.9+/-0.9 mmol/l), metabolic acidosis (plasma bicarbonate 11+/-1.4 mmol/l), and a rise in serum creatinine levels (145+/-101 micromol/l) were associated with high urinary sodium (Na) and low potassium (K) excretion. Tubular resistance to aldosterone was indicated by high plasma aldosterone concentrations (170.4+/-100.5 ng/dl), high levels of the plasma aldosterone to potassium ratio (25.2+/-15.6), and diminished urinary K/Na values (0.31+/-0.19). With appropriate therapy, serum electrolytes, creatinine, and acid-base balance normalized within 2 weeks. A Medline search revealed another 85 cases of TPHA1 reported to date. All of the 93 patients were less than 7 months of age and 90% were less than 3 months of age, 90.3% suffered from UTM, with associated UTI in 89% of them, 11% had UTMin the absence of UTI, and 9.7% showed isolated UTI. These findings indicate that early infancy is the main contributing factor for TPHA1 to occur and that UTI and UTMare additional factors, with at least one being required for its development.

Transient Pseudohypoaldosteronism due to Urinary Tract Infection in Infancy: A Report of 4 Cases

Hyponatremia with hyperkalemia in infancy is an uncommon but life-threatening occurrence. In the first weeks of life, this scenario is often associated with aldosterone deficiency due to salt-wasting congenital adrenal hyperplasia. However, alternative diagnoses involving inadequate mineralocorticoid secretion or action must be considered, particularly for infants one month of age or older. We report four infants who presented with profound hyponatremia accompanied by urinary tract infection, ultimately leading to the diagnosis of transient pseudohypoaldosteronism. Our cases provide support for the idea that the renal tubular resistance to aldosterone is due to urinary tract infection itself rather than to underlying urinary tract anomalies typically found in these infants. Awareness of this condition is important so that serum aldosterone, urine sodium, and urine cultures may be obtained immediately in any infant presenting with hyponatremia and hyperkalemia in whom a diagnosis of congenital adrenal hyperplasia was not found. Adequate replacement with intravenous saline and antibiotic therapy is sufficient to correct sodium levels over 24–48 hours.

Congenital anomalies of the male urethra

The spectrum of congenital anomalies of the male urethra is presented. The embryologic basis of each anomaly, when known, is discussed. Clinical and imaging features of each entity are presented.

Pseudohypoaldosteronism associated with ureterocele and upper pole moiety obstruction

A 2-month-old girl was diagnosed with a febrile urinary tract infection. Subsequent studies revealed a right renal duplication anomaly with a poorly functioning upper pole moiety subtended by an intravesical ureterocele. The patient was also found to have hyperkalemia, hyponatremia, and elevated serum aldosterone. After antibiotic therapy, the urinary tract infection resolved, although the electrolyte and hormonal abnormalities persisted. At 4 months of age, a right upper pole heminephrectomy was performed. The patient's electrolyte and hormonal levels normalized. This case represents an unusual case of pseudohypoaldosteronism presenting with urinary tract infection and obstructed upper pole moiety that resolved after surgical intervention.

Ventricular flutter in a neonate--severe electrolyte imbalance caused by urinary tract infection in the presence of urinary tract malformation

Male infants under the age of 3 months presenting with pyelonephritis in the presence of urinary tract malformation (UTM) are prone to transient pseudohypoaldosteronism. This may resemble congenital adrenal hyperplasia (CAH). Hyponatremia, hyperkalemia, dehydration, and metabolic acidosis are the primary findings that permit the diagnosis of CAH. We report a case of transient pseudohypoaldosteronism resulting from pyelonephritis and vesicouretric reflux. The 17-day-old boy presented with a salt-losing episode simulating adrenal insufficiency. An initial diagnosis of CAH was made. The severe metabolic imbalance resulted in ventricular flutter that resolved after correction of the metabolic acidosis and the electrolyte and volume depletion. Early diagnosis is essential because both conditions are potentially fatal and treatment differs significantly. Differential diagnosis may be achieved by urinalysis and abdominal ultrasound scan.

Sonography of the neonatal genitourinary tract

Ultrasound has become the modality of choice for the evaluation of the neonatal genitourinary tract. High frequency linear, vector, and curved array transducers (7 MHz, 5 MHz, 12 MHz) and portability of the equipment make a rapid bedside evaluation with exquisite anatomic detail possible. A major advantage of sonography over other modalities is real time observation and circumvention of sedation.

Hyponatraemia and hyperkalaemia in acute pyelonephritis without urinary tract anomalies

Three children with severe hyponatraemia and hyperkalaemia associated with acute pyelonephritis are reported. All were very young male infants in a poor general condition and seriously dehydrated. Diagnostic procedures did not detect obstructive uropathy or vesico-ureteric reflux.

CONCLUSION

Hyponatraemia and hyperkalaemia occurs in young infants with severe acute pyelonephritis in the absence of obstructive uropathy or vesico-ureteric reflux. The severe inflammation of the kidney itself may explain the electrolyte disturbance by a transient resistance of the distal tubule to aldosterone.

Hormone-nuclear receptor interactions in health and disease. Mineralocorticoid resistance

Mineralocorticoid resistance, or pseudohypoaldosteronism (PHA), is a rare cause of salt wasting in young children. It may be inherited as an autosomal dominant or recessive trait, it may occur sporadically or, rarely, it may develop secondary to other conditions. It is characterized by episodes of dehydration and hyponatraemia in the face of high aldosterone levels. In most cases, after a short period of salt supplementation no further ill effects are experienced. The condition is of great interest because it provides insights into both the mechanisms by which salt and water balance are controlled and the actions of aldosterone. This article reviews the normal physiology of aldosterone, with particular reference to its biosynthesis and its actions in specific target tissues. Current knowledge regarding the molecular mechanisms involved in aldosterone action is discussed in some detail. The clinical features of PHA are reviewed and diagnostic issues and clinical management considered. Finally, current views regarding the pathophysiology of the condition are presented. Here, considerable uncertainty remains. Whilst in many cases of PHA there is greatly reduced binding of aldosterone to its receptor, the underlying abnormality is yet to be identified; in particular, in spite of strong reasons for suspecting a defect or defects in the mineralocorticoid receptor, there is so far no direct evidence to support this hypothesis. The article concludes with a discussion of other possible explanations for the underlying abnormality in PHA.