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Disorders of isolated mineralocorticoid deficiency, which cause potentially life-threatening salt-wasting crisis early in life, have been associated with gene variants of aldosterone biosynthesis or resistance; however, in some patients no such variants are found. WNT/β-catenin signaling is crucial for differentiation and maintenance of the aldosterone-producing adrenal zona glomerulosa (zG). Herein, we describe a highly consanguineous family with multiple perinatal deaths and infants presenting at birth with failure to thrive, severe salt-wasting crises associated with isolated hypoaldosteronism, nail anomalies, short stature, and deafness. Whole exome sequencing revealed a homozygous splice variant in the R-SPONDIN receptor LGR4 gene (c.618-1G>C) regulating WNT signaling. The resulting transcripts affected protein function and stability and resulted in loss of Wnt/β-catenin signaling in vitro. The impact of LGR4 inactivation was analyzed by adrenal cortex-specific ablation of Lgr4, using Lgr4fl/fl mice mated with Sf1:Cre mice. Inactivation of Lgr4 within the adrenal cortex in the mouse model caused decreased WNT signaling, aberrant zonation with deficient zG, and reduced aldosterone production. Thus, human LGR4 mutations establish a direct link between LGR4 inactivation and decreased canonical WNT signaling, which results in abnormal zG differentiation and endocrine function. Therefore, variants in WNT signaling and its regulators should systematically be considered in familial hyperreninemic hypoaldosteronism.

Background RMND1 is a nuclear gene needed for proper function of mitochondria. A pathogenic gene will cause multiple oxidative phosphorylation defects. A renal phenotype consisting of hyponatremia, hyperkalemia, and acidosis is frequently reported, previously considered to be due to aldosterone insensitivity. Methods Clinical features and pathophysiology of three patients will be reported. DNA of these patients was subjected to exome screening. Results In the first family, one pathogenic heterozygous and one highly probable heterozygous mutation were detected. In the second family, a homozygous pathogenic mutation was present. The electrolyte disbalance was not due to aldosterone insensitivity but to low plasma aldosterone concentration, a consequence of low plasma renin activity. This disbalance can be treated. In all three patients, the kidney function declined. In the first family, both children suffered from an unexplained arterial thrombosis with dire consequences. Conclusions Hyporeninemic hypoaldosteronism is the mechanism causing the electrolyte disbalance reported in patients with RMND1 mutations, and can be treated.

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.

Selective hypoaldosteronism (SH) is a condition manifested by hyperkalemia due to low aldosterone secretion with normal cortisol. One of the obstacles in diagnosis is the awareness of the condition itself. The objective of this review is to highlight what is known about the epidemiology, pathophysiology, etiology, presentation, diagnosis, and treatment of SH. Literature search was performed on PubMed and Ovid Medline for articles which contained hypoaldosteronism as a major topic. The recent literature on this topic is surprisingly limited. Few recent review articles were found, none of which were in English and less than 5 years old. Case reports and genetic literature were also included in this review, as they contain the most recent reports of SH in the literature. Awareness about SH will hopefully help physicians to identify patients at risk as well as decide on treatment if any therapy is required.

Background Genome-wide association studies (GWASs) have linked RRBP1 (ribosomal-binding protein 1) genetic variants to atherosclerotic cardiovascular diseases and serum lipoprotein levels. However, how RRBP1 regulates blood pressure is unknown. Methods To identify genetic variants associated with blood pressure, we performed a genome-wide linkage analysis with regional fine mapping in the Stanford Asia–Pacific Program for Hypertension and Insulin Resistance (SAPPHIRe) cohort. We further investigated the role of the RRBP1 gene using a transgenic mouse model and a human cell model. Results In the SAPPHIRe cohort, we discovered that genetic variants of the RRBP1 gene were associated with blood pressure variation, which was confirmed by other GWASs for blood pressure. Rrbp1 - knockout (KO) mice had lower blood pressure and were more likely to die suddenly from severe hyperkalemia caused by phenotypically hyporeninemic hypoaldosteronism than wild-type controls. The survival of Rrbp1 -KO mice significantly decreased under high potassium intake due to lethal hyperkalemia-induced arrhythmia and persistent hypoaldosteronism, which could be rescued by fludrocortisone. An immunohistochemical study revealed renin accumulation in the juxtaglomerular cells of Rrbp1 -KO mice. In the RRBP1 -knockdown Calu-6 cells, a human renin-producing cell line, transmission electron and confocal microscopy revealed that renin was primarily retained in the endoplasmic reticulum and was unable to efficiently target the Golgi apparatus for secretion. Conclusions RRBP1 deficiency in mice caused hyporeninemic hypoaldosteronism, resulting in lower blood pressure, severe hyperkalemia, and sudden cardiac death. In juxtaglomerular cells, deficiency of RRBP1 reduced renin intracellular trafficking from ER to Golgi apparatus. RRBP1 is a brand-new regulator of blood pressure and potassium homeostasis discovered in this study. Graphical Abstract

Conn's Syndrome is an uncommon condition. Patients who have undergone adrenalectomy in the early postoperative period can demonstrate biochemical hypoaldosteronism. Given the rare nature of this phenomenon we investigated its incidence and whether it translated to clinical findings. A single-institution retrospective review of all patients with biochemically proven hyperaldosteronism from 2005 to 2014 that underwent unilateral adrenalectomy. A total of 29 patients fit the inclusion criteria. Functional hypoaldosteronism had appreciated in 18/29 (62%) patients, whereas 11 patients (38%) had normal postoperative aldosterone. No significant differences between diagnostic groups were found in terms of clinical outcomes (length of stay, postoperative symptomatology, and readmissions P = 0.669, 0.154, and 0.268, respectively). Two (7%) patients required medical therapy. Biochemical evidence of functional hypoaldosteronism was identified in two-thirds of patients undergoing unilateral adrenalectomy. Although contralateral aldosterone suppression can be anticipated, the phenotypic response varied and the outcomes were similar to patients with normal aldosterone levels. Current guidelines make no formal recommendations for assessment of hypoaldosteronism after adrenalectomy, resulting in varying practice paradigms. Surgeons should consider the risk of postoperative hypoaldosteronism in these patients and counsel patients accordingly. Prospective investigations should be performed to assist in development of an outcomes-based care delivery model for these patients.

A 3-year-old boy presented with polyuria and polydipsia for 18 months, along with growth failure. He was born prematurely, at 34 weeks of gestation, with a low birth weight. On examination, the child was severely underweight and hypertensive. Clinical history and evaluation could not identify any secondary causes of hypertension. There was no significant family history. An endocrine workup was planned, considering hypokalemia and metabolic alkalosis. This demonstrated hyporeninemic hypoaldosteronism and raised the possibility of apparent mineralocorticoid excess (AME) and Liddle syndrome. Clinical exome sequence analysis of HSD11B2 revealed a homozygous mutation in exon 5 (911A>G; p.His304Arg), which resulted in a missense mutation that confirmed the diagnosis of AME. A novel homozygous variant was found in the HSD11B2 gene in a subject with early onset hypertension associated with hypokalemic metabolic alkalosis, establishing the diagnosis of AME.

We aimed to assess the prevalence of and factors associated with Na + /K + imbalances in children hospitalized for febrile urinary tract infection (fUTI). This retrospective Italian multicenter study included children aged 18 years or younger (median age = 0.5 years) who were discharged with a primary diagnosis of fUTI. Na + /K + imbalances were classified as hyponatremia (sodium < 135 mEq/L), hypernatremia (sodium > 145 mEq/L), hypokalemia (potassium < 3.5 mEq/L), hyperkalemia (potassium > 5.5 mEq/L), and concurrent hyponatremia and hyperkalemia, in the absence of evidence of hemolyzed blood samples. Among the 849 enrolled children, 23% had hyponatremia, 6.4% had hyperkalemia, 2.9% had concurrent hyponatremia and hyperkalemia, 0.7% had hypokalemia, and 0.4% had hypernatremia. In the multiple logistic regression analysis, after applying the Bonferroni correction, only C-reactive protein (C-RP) levels were significantly associated with hyponatremia (OR = 1.04; 95% CI: 1.02–1.06; p  < 0.001), only age was significantly associated with hyperkalemia (OR = 1.7; 95% CI: 1.1–2.7; p  = 0.01), and only CAKUT was significantly associated with concurrent hyponatremia and hyperkalemia (OR = 4.3; 95% CI: 1.7–10.8; p  = 0.002). Even after adjusting for the presence of kidney hypoplasia, abnormal renal echogenicity, pelvi-caliceal dilation, ureteral dilation, uroepithelial thickening of the renal pelvis, bladder abnormalities, pathogen other than E. coli , concurrent hyponatremia and hyperkalemia persisted significantly associated with CAKUT (OR = 3.6; 95% CI: 1.2–10.9; p  = 0.02). Conclusion : Hyponatremia was the most common Na + /K + imbalance in children hospitalized for fUTI, followed by hyperkalemia and concurrent hyponatremia and hyperkalemia. C-RP levels were most strongly associated with hyponatremia, age with hyperkalemia, and CAKUT with concurrent hyponatremia and hyperkalemia (suggestive of transient secondary pseudo-hypoaldosteronism). Therefore, in children who develop concurrent hyponatremia and hyperkalemia during the course of a fUTI, an underlying CAKUT could be suspected. What is known: • Na+ and K+ abnormalities can occur in patients hospitalized for febrile urinary tract infection (fUTI). • Concurrent hyponatremia and hyperkalemia during fUTI may suggest transient secondary pseudo-hypoaldosteronism (TPHA), for which limited data on prevalence are available. What is new: • The most common Na+/K+ imbalance in children hospitalized with fUTI was hyponatremia (23%), followed by hyperkalemia (6.4%), concurrent hyponatremia and hyperkalemia (2.9%), hypokalemia (0.7%), and hypernatremia (0.4%). • Concurrent hyponatremia and hyperkalemia were mainly associated with CAKUT, while hyponatremia alone correlated with high C-reactive protein and hyperkalemia alone with younger age. In cases of concurrent hyponatremia and hyperkalemia during fUTI, an underlying CAKUT should be suspected.

Corticosterone methyloxidase deficiency type 2 is an autosomal recessive disorder presenting with salt loss and failure to thrive in early childhood and is caused by inactivating mutations of the gene. Herein, we describe four Turkish patients from two families who had clinical and hormonal features compatible with corticosterone methyloxidase deficiency and all had inherited novel variants. All of the patients presented with vomiting, failure to thrive and severe dehydration, except one patient with only failure to thrive. Biochemical studies showed hyponatremia, hyperkalemia and acidosis. All patients had normal cortisol response to adrenocorticotropic hormone stimulation test and had elevated plasma renin activity with low aldosterone levels. Three patients from the same family were found to harbor a novel homozygous variant c.1175T>C (p.Leu392Pro) and a known homozygous variant c.788T>A (p.Ile263Asn) in the gene. The fourth patient had a novel homozygous variant c.666_667delCT (p.Phe223ProfsTer35) in the gene which caused a frame shift, forming a stop codon. Corticosterone methyloxidase deficiency should be considered as a differential diagnosis in patients presenting with hyponatremia, hyperkalemia and growth retardation, and it should not be forgotten that this condition is life-threatening if untreated. Genetic analyses are helpful in diagnosis of the patients and their relatives. Family screening is important for an early diagnosis and treatment. In our cases, previously unreported novel variants were identified which are likely to be associated with the disease.