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

Renal pseudohypoaldosteronism type 1-an adult case series including a novel gene variant

PURPOSE

Renal pseudohypoaldosteronism type 1 (PHA1) is a rare disease affecting infants. Symptoms are failure to thrive, vomiting, and weight loss. It is caused by gene variants in NR3C2 by which the mineralocorticoid receptor is dysfunctional, and patients develop hyponatremia, elevated plasma aldosterone, and renin but have normal blood pressure. Little is known about PHA1 in adults. We present four adults with PHA1, their clinical, biochemistry, and genetic data.

METHODS

Clinical and biochemical data were collected from the medical files and clinical examination of the participants. Genetic testing was performed.

RESULTS

Two adult dizygotic twins and their mother, as well as an adult man were included. One of the sisters and the man had had severe hyponatremia and been admitted several times as young infants, treated with sodium chloride and fludrocortisone. All had as adults elevated plasma aldosterone and normal sodium. The females now had normal plasma renin, but it was increased in the male. A novel genetic variant in NR3C2 was found in the twins and their mother (c.1816T>C, p.(Cys606Arg)). All had normal blood pressure and were asymptomatic.

CONCLUSION

In adulthood, PHA1 seems to be asymptomatic and long-term consequences favorable.

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.

Neonatal salt wasting syndrome: Aldosterone synthase deficiency caused by a new splicing variant in CYP11B2

Aldosterone synthase deficiency (ASD) is a rare autosomal recessive disorder involving isolated aldosterone deficiency without any compromise of other adrenal hormones. This condition manifests mainly in the neonatal period and in infants as a salt wasting syndrome with vomiting and failure to thrive. Due to its potentially life-threatening effects, ASD requires a careful and early diagnosis based on appropriate hormonal investigations in order to initiate adequate management: rehydration as well as salt and fludrocortisone supplementation. Genetic analysis of the CYP11B2 gene will confirm ASD in most cases. We report the case of a newborn with a typical clinical presentation associated with some uncommon phenotypic features (hyperhidrosis, liver injury). Furthermore, our patient carries a new CYP11B2 splicing variant to be added to the approximately 60 pathogenic or likely pathogenic variants already reported.

Pediatric reference intervals for endocrine markers in healthy children and adolescents on the Liaison XL (DiaSorin) immunoassay system

OBJECTIVES

Prominent physiological changes occurring throughout childhood and adolescence necessitate the consideration of age and sex in biomarker interpretation. Critical gaps exist in pediatric reference intervals (RIs) for specialized endocrine markers, despite expected influence of growth and development. The current study aimed to establish and/or verify RIs for six specialized endocrine markers on a specialized immunoassay system.

METHODS

Samples were collected from healthy children and adolescents (5 to <19 years) and apparently healthy outpatients (0 to <5 years) as part of the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER). Serum samples were analysed for aldosterone, renin (plasma), thyroglobulin, anti-thyroglobulin, growth hormone, and insulin-like growth factor-1 (IGF-1) on the Liaison XL (DiaSorin) immunoassay platform. RIs (2.5th and 97.5th percentiles) were established for aldosterone, renin, thyroglobulin, anti-thyroglobulin, and growth hormone. Manufacturer-recommended pediatric RIs for IGF-1 were verified.

RESULTS

Age-specific RIs were established for aldosterone, renin, and thyroglobulin, while no age-specific differences were observed for anti-thyroglobulin or growth hormone. IGF-1 was the only endocrine marker studied that demonstrated significant sex-specific differences. Manufacturer-recommended IGF-1 RIs were verified for children aged 6 to <19 years, while those for children aged 0 to <6 years did not verify.

CONCLUSIONS

This study marks the first time that pediatric RIs for aldosterone and renin were established in the CALIPER cohort and highlights the dynamic changes that occur in water and sodium homeostasis during the first years of life. Overall, these data will assist pediatric clinical laboratories in test result interpretation and improve clinical decision-making for patients tested using Liaison immunoassays.

Genetic Diagnosis and Treatment of Inherited Renal Tubular Acidosis

Background

Renal tubular acidosis (RTA) is caused by various disruptions to the secretion of H+ by distal renal tubules and/or dysfunctional reabsorption of HCO3- by proximal renal tubules, which causes renal acidification dysfunction, ultimately leading to a clinical syndrome characterized by hyperchloremic metabolic acidosis with a normal anion gap. With the development of molecular genetics and gene sequencing technology, inherited RTA has also attracted attention, and an increasing number of RTA-related pathogenic genes have been discovered and reported.

Summary

This paper focuses on the latest progress in the research of inherited RTA and systematically reviews the pathogenic genes, protein functions, clinical manifestations, internal relationship between genotypes and clinical phenotypes, diagnostic clues, differential diagnosis, and treatment strategies associated with inherited RTA. This paper aims to deepen the understanding of inherited RTA and reduce the missed diagnosis and misdiagnosis of RTA.

Key Messages

This review systematically summarizes the pathogenic genes, pathophysiological mechanisms, differential diagnosis, and treatment of different types of inherited RTA, which has good clinical value for guiding the diagnosis and treatment of inherited RTA.

Serum electrolyte abnormalities in pediatric patients presenting to an emergency department with various diseases: Age-related differences

BACKGROUND

This study evaluated the prevalence and frequency of serum electrolyte abnormalities (SEAs) in children presenting to a pediatric emergency department (PED) with various diseases.

METHODS

Pediatric patients (≤18 years) with blood electrolyte panels obtained in the PED of Lin-Kou Chang Gung Memorial Hospital, Taiwan, in the 5 years from January 1, 2016, to August 31, 2021, were enrolled in this retrospective observational study. Patients were divided into three age groups: Group A, < 4 years; Group B, 4-11 years; and Group C, 12-18 years. The associations between SEAs and clinical diseases in children and age-related differences were assessed.

RESULTS

This study included 182,058 pediatric patients visiting our PED over a 5-year period. A total of 250 (0.14%) patients with SEAs were included in the analysis. The study population consisted of 127 boys and 123 girls with a median (IQR) age of 9.0 (3.2-14.1) years. Hospital admission was required in 86.4% (n = 216) of the patients, and 32.4% (n = 81) of them were admitted to the pediatric intensive care unit (PICU). The median (IQR) hospital stay and PICU stay was 6.5 (4.0-11.0) and 4.0 (3.0-8.0) days, respectively. The PICU stay was longer in Group A (p < 0.05) and shorter in group C (p < 0.05). Hyponatremia was the most common SEA in group A (46.3%, n = 31), while hypokalemia was common in groups B (54.2%, n = 52) and C (32.2%, n = 28). Gastrointestinal, renal, and endocrine diseases were common clinical conditions associated with SEAs in pediatric patients in our PED.

CONCLUSION

The detection rate of SEAs in patients in the PED was 0.14%. Hyponatremia was a common SEA in pediatric patients aged <4 years, while the most common electrolyte disorder in those >4 years old was hypokalemia. In infants and young children, SEAs were associated with a longer PICU stay.

Vancomycin dosing required to achieve a therapeutic level in children post-surgical correction of congenital heart disease

The vancomycin dosing range for safe and effective treatment remains uncertain for children who had corrective surgery for a congenital heart disease (CHD). We aimed to determine the vancomycin dosing requirements for this subgroup of patients. This prospective cohort study included children younger than 14 years old with CHD who received intravenous vancomycin for at least 3 days at the Pediatric Cardiology section of King Abdulaziz Medical City, Riyadh. In total, 140 pediatric patients with CHD were included with a median age of 0.57 years (interquartile range 0.21-2.2). The mean vancomycin total daily dose (TDD), 37.71 ± 6.8 mg/kg/day, was required to achieve a therapeutic trough concentration of 7-20 mg/L. The patient's age group and the care setting were significant predictors of the vancomycin dosing needs. Neonates required significantly lower doses of 34 ± 6.03 mg/kg/day (P = .002), and young children higher doses of 43.97 ± 9.4 mg/kg/day (P = .003). The dosage requirements were independent of the type of cardiac lesion, cardiopulmonary surgery exposure, sex, and BMI percentile. However, the patients in the pediatric cardiac ward required higher doses of vancomycin 41.08 ± 7.06 mg/kg/day (P = .039). After the treatment, 11 (8.5%) patients had an elevated Scr, and 3 (2.3%) patients developed AKI; however, none of the patients' sociodemographic factors or clinical variables, or vancomycin therapy characteristics was significantly associated with the renal dysfunction. Overall, the vancomycin TDD requirements are lower in pediatric post-cardiac surgery compared to non-cardiac patients and are modulated by several factors.

Vasopressin associated hyponatremia in critically ill children: A cross-sectional study

Background

The association of hyponatremia with vasopressin therapy in children is controversial. We aimed to evaluate the incidence and severity of hyponatremia associated with the administration of vasopressin in critically ill pediatric patients.

Methods

This retrospective cross-sectional study included children younger than 14 years who were admitted to the pediatric or pediatric cardiac intensive care units and received vasopressin for at least 24 h.

Results

In total, 176 critically ill pediatric patients were enrolled, with a median age of 22 days (7.3–146). The mean sodium level was notably decreased from 143.5 mEq/L ± 7.15 at the baseline to 134.3 mEq/L ± 7.7 at the 72-hour measurement after the initiation of vasopressin and varied significantly at all intervals from the baseline measurement (P < 0.001). Twenty-four hours after the discontinuation of vasopressin, more than half of the patients had hyponatremia. The highest proportion had mild hyponatremia (32.8%), followed by moderate hyponatremia (13.1%), and profound hyponatremia (7.5%). The incidence of hyponatremia was independent of gender (P = 0.94) or age group (P = 0.087). However, more than two-thirds of the moderate-profound cases and more than one-third of mild cases were observed in the neonate group (P = 0.043). The vasopressin dose did not affect the incidence (P = 0.25) or the severity of the hyponatremia (P = 0.56). Notably, all laboratory and hemodynamic parameters varied significantly at the end of therapy, compared to the baseline.

Conclusions

Continuous monitoring for hyponatremia when children are placed on vasopressin is essential to protect against more severe complications.

Catch-up Growth and Discontinuation of Fludrocortisone Treatment in Aldosterone Synthase Deficiency

BACKGROUND

Aldosterone synthase deficiency (ASD) caused by mutations in the CYP11B2 gene is characterized by isolated mineralocorticoid deficiency. Data are scarce regarding clinical and biochemical outcomes of the disease in the follow-up.

OBJECTIVE

Assessment of the growth and steroid profiles of patients with ASD at the time of diagnosis and after discontinuation of treatment.

DESIGN AND METHOD

Children with clinical diagnosis of ASD were included in a multicenter study. Growth and treatment characteristics were recorded. Plasma adrenal steroids were measured using liquid chromatography-mass spectrometry. Genetic diagnosis was confirmed by CYP11B2 gene sequencing and in silico analyses.

RESULTS

Sixteen patients from 12 families were included (8 females; median age at presentation: 3.1 months, range: 0.4 to 8.1). The most common symptom was poor weight gain (56.3%). Median age of onset of fludrocortisone treatment was 3.6 months (range: 0.9 to 8.3). Catch-up growth was achieved at median 2 months (range: 0.5 to 14.5) after treatment. Fludrocortisone could be stopped in 5 patients at a median age of 6.0 years (range: 2.2 to 7.6). Plasma steroid profiles revealed reduced aldosterone synthase activity both at diagnosis and after discontinuation of treatment compared to age-matched controls. We identified 6 novel (p.Y195H, c.1200 + 1G > A, p.F130L, p.E198del, c.1122-18G > A, p.I339_E343del) and 4 previously described CYP11B2 variants. The most common variant (40%) was p.T185I.

CONCLUSIONS

Fludrocortisone treatment is associated with a rapid catch-up growth and control of electrolyte imbalances in ASD. Decreased mineralocorticoid requirement over time can be explained by the development of physiological adaptation mechanisms rather than improved aldosterone synthase activity. As complete biochemical remission cannot be achieved, a long-term surveillance of these patients is required.

[Congenital adrenal hyperplasia due to 11β-hydroxylase deficiency: late diagnosis and gender reassignment in a two-year-old child]

11β-hydroxylase deficiency is a rare autosomal recessive disorder due to impaired steroidogenesis in the adrenal cortex caused by pathogenic mutations in the CYP11B1 gene. The main clinical manifestations are determined by a deficiency of cortisol, ACTH hyperproduction, excessive androgens secretion and the accumulation of 11-deoxycorticosterone, which leads to the development of arterial hypertension. In the diagnostic search, it is important to take into account the ethnicity of the patient, since the frequency of the disease and the prevalence of mutations differ between ethnic groups. The article presents a clinical case of 11β-hydroxylase deficiency as the result of compound heterozygous mutations in the CYP11B1 gene in a patient of Turkic origin. This case shows the clinical manifestations and the development of complications of 11β-hydroxylase deficiency, the stages of differential diagnosis of patients with 21-hydroxylase deficiency.

Aldosterone signaling defect in young infants: single-center report and review

BACKGROUND

Aldosterone (Ald) is a crucial factor in maintaining electrolyte and water homeostasis. Defect in either its synthesis or function causes salt wasting (SW) manifestation. This disease group is rare, while most reported cases are sporadic. This study aimed to obtain an overview of the etiology and clinical picture of patients with the above condition and report our rare cases.

METHODS

A combination of retrospective review and case studies was conducted at the Pediatric Endocrine unit of The First Affiliated Hospital Sun Yat Sen University from September 1989 to June 2020.

RESULTS

A total of 187 patients with SW were enrolled, of which 90.4% (n = 169) were diagnosed with congenital adrenal hyperplasia (CAH). SW type 21-hydroxylase deficiency accounted for 98.8% (n = 167) of CAH diagnosis, while 1.2% (n = 2) was of lipoid CAH. Non-CAH comprised 9.6% (n = 18) of the total patients whose etiologies included SF-1 gene mutation (n = 1), X-linked adrenal hypoplasia congenita (n = 9), aldosterone synthase deficiency (ASD, n = 4), and pseudo-hypoaldosteronism type 1 (PHA1, n = 1). Etiologies were not identified in three patients. All of patients with ASD and PHA1 exhibited SW syndrome in their early neonatal period. DNA sequencing showed mutations of CYP11B2 for P1-P4 and NR3C2 for P5. P1 and P2 were sibling brothers affected by compound heterozygous mutations of c.1121G > A (p.R374Q) and c.1486delC p.(L496fs); likewise, P4 was identified with compound heterozygous mutations of c.1200 + 1G > A and c.240-1 G > T; meanwhile P3 demonstrated c.1303G > A p.(G435S) homozygous mutation in CYP11B2 gene. Lastly, P5 showed c.1768 C > T p.(R590*) heterozygous mutation in the NR3C2 gene.

CONCLUSION

Etiology of infant with aldosterone defect was mostly congenital. Renal and adrenal imaging are recommended to exclude renal causes. If clinical picture is suggestive, normal plasma Ald in early infancy cannot rule out aldosterone insufficiency.

Clinical and Genetic Characteristics of Patients with Corticosterone Methyloxidase Deficiency Type 2: Novel Mutations in CYP11B2

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 CYP11B2 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 CYP11B2 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 CYP11B2 gene. The fourth patient had a novel homozygous variant c.666_667delCT (p.Phe223ProfsTer35) in the CYP11B2 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.

Systemic pseudohypoaldosteronism-1 with episodic dyslipidemia in a Sudanese child

SUMMARY

Systemic pseudohypoaldosteronism type 1 (PHA1) is a rare genetic syndrome of tissue unresponsiveness to aldosterone caused by mutations affecting the epithelial Na channel (ENaC). The classical presentation is life-threatening neonatal/infantile salt-losing crises that mimic congenital adrenal hyperplasia (CAH). Consistently, extra-renal manifestations, including respiratory symptoms that resemble cystic fibrosis, are well reported. Clinical diagnosis is made by the presence of hyponatremia, hyperkalemia, metabolic acidosis, respiratory symptoms, evidence of high renal and extra-renal salt loss in addition to high plasma renin and aldosterone levels. We herein report a novel manifestation of PHA1: episodic dyslipidemia in a 7-month-old Sudanese boy that occurred during the salt-losing crises. Whole exome sequencing of the patient revealed one homozygous missense variant c.1636G>A p.(Asp546Asn) in the SCNN1B gene, confirming our clinical and laboratory findings that were compatible with PHA1. This report aims to highlight the possible explanation of dyslipidemia in PHA1 and its expected consequences in the long term.

LEARNING POINTS

A child presenting with features that mimic salt-losing congenital adrenal hyperplasia (CAH) crises that do not respond to glucocorticoid and mineralocorticoid therapy should alert the pediatricians to the possibility of end-organ resistance to aldosterone. Pseudohypoaldosteronism type 1 (PHA1) can be diagnosed even in the absence of advanced laboratory investigations. To our knowledge, this is the first case of systemic PHA1 to have a documented episodic dyslipidemia (primarily as marked hypertriglyceridemia).

Case Report: Newborns With Pseudohypoaldosteronism Secondary to Excessive Gastrointestinal Losses Through High Output Stoma

Life-threatening electrolyte imbalance is not uncommon in preemies. Differential diagnosis is important for immediate treatment. The syndrome of pseudohypoaldosteronism (PHA) is characterized by increased aldosterone secretion associated with clinical signs of hypoaldosteronism reflecting mineralocorticoid resistance. There are type I, type II, and secondary type of PHA. Most secondary PHA reported in the pediatric population result from urinary infection and obstructive uropathy and extremely rarely from gastrointestinal fluid loss. Seven preemies accepted jejunostomy or ileostomy, and they suffered from high output stoma. Electrolyte imbalance with bodyweight loss or cardiac event was noted. We found a high level of aldosterone and renin and diagnosed them with secondary PHA due to excessive gastrointestinal losses. After stomal reversal, aldosterone and renin level became normalized, and electrolyte was corrected. This study reports the finding of secondary pseudohyperaldosteronism (hyponatremia, hyperkalemia, and metabolic acidosis) in a series of cases with intestinal resection and ostomy of different causes. Early stomal reversal was recommended.

Obstetric and Neonatal Outcome of Pregnancy in Carney Complex: A Case Report

Background: Carney complex (CNC) is a rare multiple endocrine neoplasia syndrome with autosomal dominant inheritance. Affected individuals present with mucocutaneous lentigines/blue nevi, cardiac and noncardiac myxomatous tumors, and multiple endocrine tumors. Mutations in PRKAR1A have been identified as genetic cause of the disease. Here, we report on pregnancy, delivery and puerperium in a woman with genetically confirmed CNC and her newborn. Case: The 31 year-old gravida 5 para 1 with CNC was referred at 26 weeks of gestation. Adrenocorticotropin-independent hypercortisolism, hyperglycemia, hypertension, low serum potassium, and osteoporotic fractures were present. Treatment with metyrapone, a reversible 11-beta-hydroxylase inhibitor, was initiated. The maternal condition improved, and a 5 weeks' pregnancy prolongation could be achieved. Elective repeat cesarean section was performed at 31 weeks of gestation for recurrent vaginal bleeding. The neonate developed transient hyponatremia necessitating hydrocortisone substitution for 2 weeks. Conclusion: In our case, treatment of CNC-associated hypercortisolism in pregnancy with metyrapone was effective. Maternal side effects did not occur. The newborn presented with transient hypocortisolism most likely due to transplacental drug effect. Our case illustrates that the treatment of rare diseases in pregnancy represents a challenge requiring interdisciplinary team work.

Spiral steroids as potential markers for pre-eclampsia: A pilot study

Pre-eclampsia is a condition that complicates 3-6% of pregnancies. At present, there is no FDA approved diagnostic method to evaluate risk or progression. We would like to report our observation of elevated levels of the spiral steroid phosphoester precursor in patients with pre-eclampsia. Samples from 20 normotensive pregnant women and from 20 women with pre-eclampsia were purchased from Global Alliance for the Prevention of Prematurity and Stillbirth (GAPPS). After addition of miltefosine (hexadecyl phosphocholine) as an internal control, each sample was extracted and evaluated by tandem MS. The method detected 2 spiral steroid phosphoesters and their common precursor. For each mass ion, the ion counts obtained were compared to the ion counts of miltefosine. The samples from the normotensive women were used to establish the mean and standard deviation. Then, Z-scores were determined for each of the serum components. Of the samples from the women with pre-eclampsia, 12 of 19 (63%) samples had Z-scores over 2.0 for at least one of the steroid phosphoesters. In contrast, current markers under development for risk of pre-eclampsia have prediction scores ranging from 8 to 33%. As the spiral steroids are lactones, similar to spironolactone and related compounds, they could function as endogenous potassium sparing hormones. However, as only about half of the affected patients had elevated levels of the spiral steroids, it may not be the only underlying pathology. Parturition would end transfer of placental spiral steroids and account for the termination of the symptoms of pre-eclampsia/eclampsia. Previous investigators have proposed inadequate placental function as the critical pathology of pre-eclampsia, but it is hard to imagine how inadequate placental function leads to the maternal pathology without invoking an endogenous potassium sparing hormone originating in the placenta.

Analysis of novel heterozygous mutations in the CYP11B2 gene causing congenital aldosterone synthase deficiency and literature review

Aldosterone synthase deficiency (ASD) is a rare autosomal recessive disorder characterized by severe hyperkalemia, salt loss, vomiting, severe dehydration and failure to thrive. ASD is a life-threatening electrolyte imbalance in infants resulting from mutations in CYP11B2. We described ASD in a Chinese male infant with vomiting, poor feeding and failure to thrive. He was mildly dehydrated, with a weight of 6 kg (-3.45 SDS) and length of 67 cm (-3.10 SDS). Laboratory tests showed hyponatremia (119 mmol/L), serum potassium 5.4 mmol/L, low plasma aldosterone and plasma renin activity (PRA) levels. Next-generation sequencing of his DNA revealed compound heterozygous mutations in CYP11B2, a known variant c.1391_1393delTGC (p.Leu464del, rs776404064) and a novel variant c.1294delA (p.Arg432Glyfs*37). The HEK-293T expression system was used to investigate the variants, demonstrating negligible aldosterone synthesis compared with WT CYP11B2. The patient started fludrocortisone and subsequently gained 3.2 kg of weight and normalized serum sodium (137 mmol/L). We further reviewed reported cases of ASD, summarizing clinical features and CYP11B2 mutations; missense and nonsense mutations are most frequent. Fludrocortisone treatment is essential for ASD, and the need for mineralocorticoid replacement wanes with age; eventually, therapy can be discontinued for many affected children. Our study broadens the ASD phenotypic spectrum and shows the efficiency of next-generation sequencing for patients with atypical clinical manifestations.

Poisoning with Soman, an Organophosphorus Nerve Agent, Alters Fecal Bacterial Biota and Urine Metabolites: a Case for Novel Signatures for Asymptomatic Nerve Agent Exposure

The experimental pathophysiology of organophosphorus (OP) chemical exposure has been extensively reported. Here, we describe an altered fecal bacterial biota and urine metabolome following intoxication with soman, a lipophilic G class chemical warfare nerve agent. Nonanesthetized Sprague-Dawley male rats were subcutaneously administered soman at 0.8 (subseizurogenic) or 1.0 (seizurogenic) of the 50% lethal dose (LD₅₀) and evaluated for signs of toxicity. Animals were stratified based on seizing activity to evaluate effects of soman exposure on fecal bacterial biota and urine metabolites. Soman exposure reshaped fecal bacterial biota by altering Facklamia, Rhizobium, Bilophila, Enterobacter, and Morganella genera of the Firmicutes and Proteobacteria phyla, some of which are known to hydrolyze OP chemicals. However, analogous changes were not observed in the bacterial biota of the ileum, which remained the same irrespective of dose or seizing status of animals after soman intoxication. However, at 75 days after soman exposure, the bacterial biota stabilized and no differences were observed between groups. Interestingly, in considering just the seizing status of animals, we found that the urine metabolomes were markedly different. Leukotriene C₄, kynurenic acid, 5-hydroxyindoleacetic acid, norepinephrine, and aldosterone were excreted at much higher rates at 72 h in seizing animals, consistent with early multiorgan involvement during soman poisoning. These findings demonstrate the feasibility of using the dysbiosis of fecal bacterial biota in combination with urine metabolome alterations as forensic evidence for presymptomatic OP exposure temporally to enable administration of neuroprotective therapies of the future.IMPORTANCE The paucity of assays to determine physiologically relevant OP exposure presents an opportunity to explore the use of fecal bacteria as sentinels in combination with urine to assess changes in the exposed host. Recent advances in sequencing technologies and computational approaches have enabled researchers to survey large community-level changes of gut bacterial biota and metabolomic changes in various biospecimens. Here, we profiled changes in fecal bacterial biota and urine metabolome following a chemical warfare nerve agent exposure. The significance of this work is a proof of concept that the fecal bacterial biota and urine metabolites are two separate biospecimens rich in surrogate indicators suitable for monitoring OP exposure. The larger value of such an approach is that assays developed on the basis of these observations can be deployed in any setting with moderate clinical chemistry and microbiology capability. This can enable estimation of the affected radius as well as screening, triage, or ruling out of suspected cases of exposures in mass casualty scenarios, transportation accidents involving hazardous materials, refugee movements, humanitarian missions, and training settings when coupled to an established and validated decision tree with clinical features.

Sodium Chloride Supplementation Is Not Routinely Performed in the Majority of German and Austrian Infants with Classic Salt-Wasting Congenital Adrenal Hyperplasia and Has No Effect on Linear Growth and Hydrocortisone or Fludrocortisone Dose

INTRODUCTION

Sodium chloride supplementation in salt-wasting congenital adrenal hyperplasia (CAH) is generally recommended in infants, but its implementation in routine care is very heterogeneous.

OBJECTIVE

To evaluate oral sodium chloride supplementation, growth, and hydrocortisone and fludrocortisone dose in infants with salt-wasting CAH due to 21-hydroxylase in 311 infants from the AQUAPE CAH database.

RESULTS

Of 358 patients with classic CAH born between 1999 and 2015, 311 patients had salt-wasting CAH (133 females, 178 males). Of these, 86 patients (27.7%) received oral sodium chloride supplementation in a mean dose of 0.9 ± 1.4 mmol/kg/day (excluding nutritional sodium content) during the first year of life. 225 patients (72.3%) were not treated with sodium chloride. The percentage of sodium chloride-supplemented patients rose from 15.2% in children born 1999-2004 to 37.5% in children born 2011-2015. Sodium chloride-supplemented and -unsupplemented infants did not significantly differ in hydrocortisone and fludrocortisone dose, target height-corrected height-SDS, and BMI-SDS during the first 2 years of life.

CONCLUSION

In the AQUAPE CAH database, approximately one-third of infants with salt-wasting CAH receive sodium chloride supplementation. Sodium chloride supplementation is performed more frequently in recent years. However, salt supplementation had no influence on growth, daily fludrocortisone and hydrocortisone dose, and frequency of adrenal crisis.

Ionotropin is the mammalian digoxin-like material (DLM). It is a phosphocholine ester of a steroid with 23 carbon atoms

We describe a novel steroid, which we have named "Ionotropin". Its unique features are: [1] it has 23 carbon atoms and [2] it is a phosphocholine ester. There are no other known mammalian steroids with either structural feature. Ionotropin cross reacts with digoxin-specific antibodies and may be the long-sought, endogenous, mammalian digoxin-like material (DLM). Using LC-MS, we identified three other phosphocholine steroids in serum. Two of these steroids also cross-react with digoxin specific antibodies. In adrenal extracts, we found both phosphocholine esters and corresponding phospho-ethanolamine steroid esters. There are no other known phosphoethanolamine steroid esters. Together, these 8 compounds define a biosynthetic pathway from 7-dehydropregnenolone to Ionotropin. Ionotropin may be the only steroid hormone not synthesized with cholesterol as a precursor. Finally, we propose that Ionotropin serves as the endogenous potassium sparing hormone. Ionotropin provides a new understanding of renal, cardiac, gonadal and placental function.

Molecular genetic studies in a case series of isolated hypoaldosteronism due to biosynthesis defects or aldosterone resistance

BACKGROUND AND AIM

Hypoaldosteronism is associated with either insufficient aldosterone production or aldosterone resistance (pseudohypoaldosteronism). Patients with aldosterone defects typically present with similar symptoms and findings, which include failure to thrive, vomiting, hyponatremia, hyperkalemia and metabolic acidosis. Accurate diagnosis of these clinical conditions therefore can be challenging. Molecular genetic analyses can help to greatly clarify this complexity. The aim of this study was to obtain an overview of the clinical and genetic characteristics of patients with aldosterone defects due to biosynthesis defects or aldosterone resistance.

DESIGN AND PATIENTS

We investigated the clinical and molecular genetic features of 8 consecutive patients with a clinical picture of aldosterone defects seen in our clinics during the period of May 2015 through October 2017. We screened CYP11B2 for aldosterone synthesis defects and NR3C2 and the three EnaC subunits (SCNN1A, SCNN1B and SCNN1G) for aldosterone resistance.

RESULTS

We found 4 novel and 2 previously reported mutations in the genes CYP11B2, NR3C2, SCNN1A and SCNN1G in 9 affected individuals from 7 unrelated families.

CONCLUSION

Molecular genetic investigations can help confidently diagnose these conditions and clarify the pathogenicity of aldosterone defects. This study may expand the clinical and genetic correlations of defects in aldosterone synthesis or resistance.

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.