Difficulties in the diagnosis and management of eight infants with secondary pseudohypoaldosteronism.

BACKGROUND: Type 1 pseudohypoaldosteronism (PHA1) is a rare condition characterized by the resistance of the kidney to the effect of aldosterone. Secondary PHA1 is a syndrome that is most often related to urinary tract anomalies (UTAs) and/or urinary tract infections (UTIs). A similar pattern of electrolyte impairment is seen in congenital adrenal hyperplasia (CAH) and secondary PHA1, and CAH is a condition that requires urgent treatment. In our study, eight patients aged between 15 days and 8 months (seven males and one female) were included in the evaluation. It was aimed to evaluate cases of secondary PHA1 in our clinic and to identify the problems encountered in diagnosis and follow-up. METHODS: The records of the patients who presented to our hospital between February 2010 and 2021 were retrieved and retrospectively scanned. RESULTS: In all cases, hyponatremia, hyperkalemia, hyperaldosteronism, and hyperreninemia were detected. Other biochemical and hormonal tests were normal. Leukocytosis was detected in urine analysis, and urine cultures were productive. UTA was detected in five cases. Nine episodes of PHA1 occurred in eight patients and fungal infections were responsible for causing two episodes. Four episodes of PHA1 needed mineralocorticoid treatment. On the third day, serum electrolytes normalized. Fludrocortisone treatment was continued for 1 week. In one case, UTIs were repeated with PHA1, but in the follow-up, there were no additional problems. CONCLUSIONS: Secondary PHA1 should be kept in mind when hyponatremia and hyperkalemia are seen, especially in infants aged under 3 months or older, up to 8 months, who present with non-specific symptoms. Fungal infections should not be forgotten in UTI etiology because PHA1 episodes can be initiated. If CAH is suspected, mineralocorticoid treatment should be rapidly initiated.

A late diagnosis of Pseudohypoaldosteronism type I in an infant with hypoplastic left heart syndrome presenting with failure to thrive.

Pseudohypoaldosteronism type I is caused by a peripheral resistance to aldosterone and can present with electrolyte abnormalities, poor growth, or dehydration. Although a rare disease, several case reports have been published regarding Pseudohypoaldosteronism type I in neonates and infants. We report a case of failure to thrive and hyponatremia in an infant with hypoplastic left heart syndrome who was subsequently found to have Pseudohypoaldosteronism type I.

Rare case of pseudohypoaldosteronism in a neonate secondary to congenital hydrometrocolpos.

Pseudohypoaldosteronism (PHA) due to obstructive uropathy, urinary tract infections and congenital urogenital malformations has been reported in the literature; however, there are no reports of PHA associated with hydrometrocolpos due to a common urogenital tract. Hydrometrocolpos is a condition resulting in distension of the vagina and uterus due to accumulation of secretions (other than blood), caused by increased oestrogenic stimulation and vaginal outflow obstruction. We report on a neonatal case of PHA caused by recurrent hydrometrocolpos presenting with vomiting and poor weight gain. There was significant hyponatraemia, hyperkalaemia, and anaemia requiring medical stabilisation prior to surgery. The mechanism by which PHA occurs in obstruction involves renal tubular dysfunction due to pressure from hydronephrosis and the release of intrarenal cytokines. In addition, there is an immature or resistant renal tubular responsiveness to aldosterone during infancy. Clinicians should be aware of this uncommon but serious presentation.

Cullin-Ring ubiquitin ligases in kidney health and disease.

PURPOSE OF REVIEW: Members of the Cullin family act as scaffolds in E3 ubiquitin ligases and play a central role in mediating protein degradation. Interactions with many different substrate-binding adaptors permit Cullin-containing E3 ligases to participate in diverse cellular functions. In the kidney, one well established target of Cullin-mediated degradation is the transcription factor Nrf2, a key player in responses to oxidative stress. The goal of this review is to discuss more recent findings revealing broader roles for Cullins in the kidney. RECENT FINDINGS: Cullin 3 acts as the scaffold in the E3 ligase regulating Nrf2 abundance, but was more recently shown to be mutated in the disease familial hyperkalemic hypertension. Studies seeking to elucidate the molecular mechanisms by which Cullin 3 mutations lead to dysregulation of renal sodium transport will be discussed. Disruption of Cullin 3 in mice unexpectedly causes polyuria and fibrotic injury suggesting it has additional roles in the kidney. We will also review recent transcriptomic data suggesting that other Cullins are also likely to play important roles in renal function. SUMMARY: Cullins form a large and diverse family of E3 ubiquitin ligases that are likely to have many important functions in the kidney.

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.

A potential serious complication in infants with congenital obstructive uropathy: Secondary pseudohypoaldosteronism.

Patients who have secondary pseudohypoaldosteronism (PHA) in addition to hyponatraemia, hyperpotassaemia and high serum aldosterone levels for the age were included in this retrospective study.Among eight patients, seven patients were diagnosed with PHA secondary to obstructive uropathy (OUP), whereas one patient had PHA secondary to ileostomy. Six patients with OUP had simultaneous urinary tract infection (UTI) and in all except one patient, secondary PHA recovered with only UTI treatment before applying surgical correction. All the patients were younger than 3 months age. In three patients with PUV diagnosis, salt wasting recurred in an UTI episode under 3 months of age.

Decreased KLHL3 expression is involved in the pathogenesis of pseudohypoaldosteronism type II caused by cullin 3 mutation in vivo.

BACKGROUND: Pseudohypoaldosteronism type II (PHAII) is a hereditary hypertensive disease caused by mutations in four genes: WNK1, WNK4, Kelch-like3 (KLHL3), and cullin3 (CUL3). Recently, it was revealed that CUL3-KLHL3 E3 ligase complex ubiquitinates WNK1 and WNK4, leading to their degradation, and that a common pathogenesis of PHAII is defective WNK degradation due to CUL3-KLHL3 E3 ligase complex impairment. PHAII-causing CUL3 mutations mediate exon9 skipping, producing a CUL3 protein with a 57-amino acid deletion (Δ403-459). However, the pathogenic effects of KLHL3, an adaptor protein that links WNKs with CUL3, in PHAII caused by CUL3 mutation remain unclear. METHODS: To clarify detailed pathophysiological mechanisms underlying PHAII caused by CUL3 mutation in vivo, we generated and analyzed knock-in mice carrying the same CUL3 exon9 deletion (CUL3WT/Δex9) as that reported in PHAII patients. RESULTS: CUL3WT/Δex9 mice exhibited a PHAII-like phenotype. Interestingly, we confirmed markedly decreased KLHL3 expression in CUL3WT/Δex9 mice by confirming the true KLHL3 band in vivo. However, the expression of other KLHL family proteins, such as KLHL2, was comparable between WT and mutant mice. CONCLUSION: KLHL3 expression was decreased in CUL3WT/Δex9 mice. However, expression levels of other KLHL family proteins were comparable between the wild-type and mutant mice. These findings indicate that the decreased abundance of KLHL3 is a specific phenomenon caused by mutant CUL3 (Δexon9). Our findings would improve our understanding of the pathogenesis of PHAII caused by CUL3 mutation in vivo.

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.

A molecular update on pseudohypoaldosteronism type II.

The DCT (distal convoluted tubule) is the site of microregulation of water reabsorption and ion handling in the kidneys, which is mainly under the control of aldosterone. Aldosterone binds to and activates mineralocorticoid receptors, which ultimately lead to increased sodium reabsorption in the distal part of the nephron. Impairment of mineralocorticoid signal transduction results in resistance to aldosterone and mineralocorticoids, and, therefore, causes disturbances in electrolyte balance. Pseudohypoaldosteronism type II (PHAII) or familial hyperkalemic hypertension (FHHt) is a rare, autosomal dominant syndrome characterized by hypertension, hyperkalemia, metabolic acidosis, elevated or low aldosterone levels, and decreased plasma renin activity. PHAII is caused by mutations in the WNK isoforms (with no lysine kinase), which regulate the Na-Cl and Na-K-Cl cotransporters (NCC and NKCC2, respectively) and the renal outer medullary potassium (ROMK) channel in the DCT. This review focuses on new candidate genes such as KLHL3 and Cullin3, which are instrumental to unraveling novel signal transductions pathways involving NCC, to better understand the cause of PHAII along with the molecular mechanisms governing the pathophysiology of PHAII and its clinical manifestations.

Impaired KLHL3-mediated ubiquitination of WNK4 causes human hypertension.

Mutations in WNK kinases cause the human hypertensive disease pseudohypoaldosteronism type II (PHAII), but the regulatory mechanisms of the WNK kinases are not well understood. Mutations in kelch-like 3 (KLHL3) and Cullin3 were also recently identified as causing PHAII. Therefore, new insights into the mechanisms of human hypertension can be gained by determining how these components interact and how they are involved in the pathogenesis of PHAII. Here, we found that KLHL3 interacted with Cullin3 and WNK4, induced WNK4 ubiquitination, and reduced the WNK4 protein level. The reduced interaction of KLHL3 and WNK4 by PHAII-causing mutations in either protein reduced the ubiquitination of WNK4, resulting in an increased level of WNK4 protein. Transgenic mice overexpressing WNK4 showed PHAII phenotypes, and WNK4 protein was indeed increased in Wnk4(D561A/+) PHAII model mice. Thus, WNK4 is a target for KLHL3-mediated ubiquitination, and the impaired ubiquitination of WNK4 is a common mechanism of human hereditary hypertension.

Secondary pseudohypoaldosteronism caused by urinary tract infection associated with urinary tract anomalies: case reports.

Secondary pseudohypoaldosteronism type 1 develops due to transient aldosterone resistance in renal tubules and is characterized by renal sodium loss, hyponatremia, hyperkalemia and high plasma aldosterone levels. Although many reasons are described, urinary tract infections and/or urinary tract anomalies are the most common causes. Although the cause of the tubular resistance is not known exactly, renal scar development due to obstruction and reduced sensitivity of mineralocorticoid receptors due to cytokines such as transforming growth factor (TGF)-beta are the possible mechanisms. It is seen especially within the first three months of life and the frequency decreases with age. The treatment is usually elimination of the underlying cause. In this article, we present four patients with several urinary tract anomalies and concomitant urinary tract infection who developed transient secondary pseudohypoaldosteronism.

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.

UNLABELLED: 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.

[Pseudohypoaldosteronism type 1 in an infant with bilateral primary obstructive megaureter : a case report].

A 35-day-old male infant was referred to our hospital for bilateral hydroureteronephrosis on postnatal ultrasonography. He was born at 37 weeks and 2 days of gestation, weighing 2,765 g. He was diagnosed with bilateral primary obstructive megaureter. During observation, at 3 months and 2 weeks of age, he presented with dehydration and showed hyponatremia and hyperkalemia. An endocrinological examination led to a diagnosis of pseudohypoaldosteronism type 1 (PHA1). After bilateral percutaneous nephrostomy, PHA1 resolved. He underwent bilateral ureteral tapering and ureteroneocystostomy at 5 months and 3 weeks of age. Since PHA1 recurred after removal of urethral catheter, urethral catheter and bilateral double-J-stent was kept until 8 months old. He was followed-up until 3 years old with no signs of PHA1 recurrence. For an infant with obstructive uropathy or vesicoureteral reflux showing hyponatremia and hyperkalemia, PHA1 should be considered.