Urinary Tract Malformation and Infection with Hyperkalemia and Decreased Fractional Excretion of Potassium in an Infant

Transient secondary pseudo-hypoaldosteronism in infants with urinary tract infections: systematic literature review

Infants with a congenital anomaly of the kidney and urinary tract sometimes present with hyponatremia, hyperkalemia, and metabolic acidosis due to under-responsiveness to aldosterone, hereafter referred to as secondary pseudo-hypoaldosteronism. The purpose of this report is to investigate pseudo-hypoaldosteronism in infant urinary tract infection. A systematic review was conducted following PRISMA guidelines after PROSPERO (CRD42022364210) registration. The National Library of Medicine, Excerpta Medica, Web of Science, and Google Scholar without limitations were used. Inclusion criteria involved pediatric cases with documented overt pseudo-hypoaldosteronism linked to urinary tract infection. Data extraction included demographics, clinical features, laboratory parameters, management, and course. Fifty-seven reports were selected, detailing 124 cases: 95 boys and 29 girls, 10 months or less of age (80% of cases were 4 months or less of age). The cases exhibited hyponatremia, hyperkalemia, acidosis, and activated renin-angiotensin II-aldosterone system. An impaired kidney function was found in approximately every third case. Management included antibiotics, fluids, and, occasionally, emergency treatment of hyperkalemia, hyponatremia, or acidosis. The recovery time averaged 1 week for electrolyte, acid-base imbalance, and kidney function. Notably, anomalies of the kidney and urinary tract were identified in 105 (85%) cases.

CONCLUSIONS

This review expands the understanding of overt transient pseudo-hypoaldosteronism complicating urinary tract infection. Management involves antimicrobials, fluid replacement, and consideration of electrolyte imbalances. Raising awareness of this condition within pediatric hospitalists is desirable.

WHAT IS KNOWN

• Infants affected by a congenital anomaly of the kidney and urinary tract may present with clinical and laboratory features resembling primary pseudo-hypoaldosteronism. • Identical features occasionally occur in infant urinary tract infection.

WHAT IS NEW

• Most cases of secondary pseudo-hypoaldosteronism associated with a urinary tract infection are concurrently affected by a congenital anomaly of the kidney and urinary tract. • Treatment with antibiotics and parenteral fluids typically results in the normalization of sodium, potassium, bicarbonate, and creatinine within approximately 1 week.

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.

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.

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.