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.

Calcineurin inhibitor-related hyperkalemia is caused by hyporeninemic hypoaldosteronism and fludrocortisone is an effective treatment: Report of a case series and review of the literature.

INTRODUCTION: Calcineurin inhibitors (CNIs) are widely used in transplantation. Although CNI-related hyperkalemia is common (10%-60.6%), the underlying pathogenetic mechanism is not well-elucidated and may lead to dose adjustment or treatment withdrawal. OBJECTIVE: The aim of this study is to describe CNI-related hyperkalemia due to hyporeninemic hypoaldosteronism in pediatric transplant recipients who were successfully treated with fludrocortisone. METHOD: In a total of 55 hematopoietic stem cell (HSCT) and 35 kidney transplant recipients followed according to institutional immunosuppression protocols, recipients diagnosed with CNI-related hyperkalemia were reviewed. Recipients who were receiving intravenous fluid, potassium, or were diagnosed with hemolysis, acute graft rejection, or had an eGFR < 30 mL/min/1.73m2, were excluded. A detailed analysis of clinical history as well as biochemical studies was carried out to reveal possible pathophysiology. RESULTS: Three pediatric transplant recipients (one HSCT, two kidney transplantation) with findings of hyperkalemia, hyponatremia, and a mild elevation in blood urea nitrogen while on CNIs were recruited. Urinary potassium excretion was diminished while sodium excretion was increased. Plasma aldosterone levels were low, and renin was not increased in response. Primary adrenal insufficiency was ruled out, and hyporeninemic hypoaldosteronism was diagnosed. CNI-related hyperkalemia was detected earlier in case 1, who had HSCT (22 days), than in the second and third cases, who had kidney transplantation (24 and 30 months post-transplantation, respectively). The discrepancy was hypothesized to be explained by higher overall CNI dose due to higher serum target CNI used in HSCT than kidney transplantation. Electrolyte imbalance was reversed upon administration of physiologic dose fludrocortisone (0.05 mg, daily), while fludrocortisone was ceased after CNI withdrawal in case 1, which is additional evidence for the etiological association of CNIs and hyporeninemic hypoaldosteronism. CONCLUSION: Our three cases strengthen the premise that CNI-related hyperkalemia may be due to hyporeninemic hypoaldosteronism, and the timing and severity may be related to CNI dose. Fludrocortisone is a safe and effective treatment in CNI-related hyperkalemia, providing maintenance of CNIs, which are one of the essential therapeutic agents for pediatric transplantation.

Variables Associated With Hyperkalemic Renal Tubular Acidosis in Solid Organ Transplant Recipients.

INTRODUCTION: The occurrence of hyperkalemic renal tubular acidosis (RTA) in the post-transplantation period is likely underestimated, and its identification remains important to offer adequate medical management. Transplant recipients frequently present with clinical and biological characteristics that may be associated with the occurrence of this complication. METHODS: This was a single-center retrospective study that compared transplanted patients with hyperkalemic RTA and a control group to identify variables associated with the occurrence of this complication. Fisher's exact test and the Mann-Whitney test, followed by multivariate logistic regression, were applied to test whether there was a significant association between hyperkalemic RTA and different variables. RESULTS: Kidney and heart transplant recipients were at greater risk of developing RTA than lung transplant recipients (p = 0.016). There was also a significant association between the development of RTA and kalemia (p < 0.01), chloremia (p < 0.01), and bicarbonatemia (p < 0.01). The significant impact of these last three variables was confirmed by the results of the multivariate logistic regression. Residual serum tacrolimus levels (p = 0.13) and creatinine levels (p = 0.17) of renal transplant patients were not significantly associated with hyperkalemic RTA. CONCLUSION: The type of transplanted organ, kalemia, chloremia, and bicarbonatemia were significantly associated with the occurrence of hyperkalemic RTA. This study calls into question certain approaches to managing this complication proposed in a number of case reports, such as reducing the target serum residual of tacrolimus or discontinuing trimethoprim-sulfamethoxazole (TMP-SMX) in favor of another antibiotic prophylactic agent, potentially exposing patients to graft rejection and opportunistic infections.

Isolated hypoaldosteronism is a cause of hypovolemic but not euvolemic hyponatremia.

Introduction: Hypoaldosteronism is characterized by hyperkalemia, and/or hypovolemic hyponatremia (HH), often accompanied by metabolic acidosis. HH is typical of hypoaldosteronism, whereas euvolemic hyponatremia (EH) is not. The purpose of the current study is to describe the characteristics of hyponatremia in hypoaldosteronism and elucidate whether EH can be considered part of the disease's spectrum. Methods: In a hypoaldosteronism cohort, we analyzed the factors associated with hyponatremia, comparing the characteristics of EH and HH and their associated factors. Correlation analyses of mineralocorticoid biomarkers, such as the transtubular potassium gradient (TTKG), the urinary Na+/K+ ratio (UNa+/UK+) with serum, and urinary electrolytes were performed in both types of hyponatremia. Results: Of 112 hypoaldosteronism episodes, 77.7% were ≥65 years old, 44.6% were women, and 80 (71.4%) had hyponatremia. Hyponatremia was negatively associated with the presence of chronic kidney disease, and positively with a hypovolemic state, malnutrition, a prior history of hyponatremia, and glucocorticoid therapy. HH: 61/80 and EH: 19/80 episodes. HH was associated with an age ≥65 years and the use of diuretics, as well as factors related to an aldosterone deficit and/or mineralocorticoid resistance. In HH but not in EH, urinary potassium was correlated with the TTKG, and urinary sodium with both the TTKG and the UNa+/UK+. Conclusion: Both HH and EH can be observed in hypoaldosteronism. However, only the former would be related to insufficient mineralocorticoid activity. Significance statement: Isolated hypoaldosteronism is a poorly understood and underdiagnosed endocrinological disorder, classically recognized only when hyperkalemia is present. The development of hypovolemic hyponatremia, however, is also easily explained by the physiopathology of the disorder. The current study addresses the features of hyponatremia when found in the context of mineralocorticoid insufficiency, and confirms an association between hypovolemic hyponatremia and isolated hypoaldosteronism. Thus, the clinical spectrum of hypoaldosteronism is extended to include hypovolemic hyponatremia as a frequent manifestation of the disorder.

When the Going Gets Tough: A Case Report and Review of Calcinosis Cutis in an Infant with Pseudo-Hypoaldosteronism.

Calcium gluconate solutions are an essential part of the intensive care medication armamentarium. Calcium-related extravasations are not an infrequent occurrence. However, occult extravasation presenting solely as an isolated mass lesion with no preceding cutaneous manifestation is rare. Calcinosis cutis is an extraosseous collection of calcium deposits in the skin and subcutaneous tissues. Multiple etiopathogenetic factors play a role in its manifestations. We illustrate a case of a seven-week-old infant diagnosed with pseudo-hypoaldosteronism with a mysterious swelling on the left leg during the third week of hospitalization, which was attributed to occult iatrogenic calcinosis cutis.

Heparin-induced hyperkalemia, can LMWH cause hyperkalemia? A systematic review.

Hyperkalemia, an elevated blood potassium concentration exceeding 5.0 mEq/L, is associated with adverse outcomes and is frequently observed in hospitalized patients. Drug-induced hyperkalemia accounts for a significant proportion of cases, with heparin, commonly used for venous thrombosis prevention, suspected to contribute, though less recognized than other heparin-related side effects. Both unfractionated heparin (UFH) and low molecular weight heparin (LMWH) have been implicated in inducing hyperkalemia, primarily through the suppression of aldosterone levels and modulation of angiotensin II receptors. This systematic review examines the relationship between heparin, particularly LMWH, and hyperkalemia. Thirteen studies involving 1407 patients were analyzed. Findings indicated a lack of highquality evidence, with no significant increase in potassium levels associated with LMWH use. LMWH did not exhibit a dose-response relationship with hyperkalemia incidence. Additionally, mechanisms underlying the hypothetical LMWHinduced hyperkalemia remained inconclusive. While this suggests that LMWH is unlikely to be a primary cause of hyperkalemia, caution is warranted, especially in patients with elevated baseline potassium levels.

Congenital hyperreninemic hypoaldosteronism: A case report.

Congenital hypoaldosteronism is a rare autosomal recessive or dominant endocrinopathy with variable penetrance, secondary to primary defects in aldosterone synthesis that could lead to hypovolemia, hyponatremia, hyperkalemia, failure to thrive, microcephaly, seizures, neurodevelopmental delay, or hearing loss. We present the case of a Colombian patient with congenital hypoaldosteronism, who owns two variants in the CPY11B2 gene, and a heterozygous pathogenic variant for nonclassical congenital adrenal hyperplasia. However, the patient missed follow-up and treatment for 6 years. At the age of 7 years, he resumed medical follow-up with laboratory findings of hyperreninemia and hypoaldosteronism, as well as clinical findings of strabismus, left mixed hyperacusis, and pathological short stature (-4.3 SD). Therefore, a trial of fludrocortisone therapy was started with subsequent improvement in renin levels, weight gain, and growth velocity. After 10 months of the start of the medication, he presented hypertension. There is no literature about the late treatment of this condition for pathological short stature.

Prolonged postoperative hypoaldosteronism related to hyperkalemia in patients with aldosterone-producing adenoma.

Hyperkalemia is developed in a part of patients with aldosterone-producing adenoma (APA) after adrenalectomy, suspected to be due to the insufficiency of aldosterone secretion. The purpose of this study is to determine the frequency and characteristics of prolonged postoperative hypoaldosteronism (PPHA) using chemiluminescent enzyme immunoassay (CLEIA). We studied 58 patients with APA with long time after adrenalectomy and whose PAC was measured using a CLEIA kit. The PAC value measured using CLEIA was significantly lower than that of using RIA between two consecutive visits before and after the shift of measuring method of PAC (median [interquantile range], 123.0 [99.8-164.0] vs. 39.5 [15.8-64.2] pg/mL, p < 0.01). PAC was below the minimum limit of quantification (4.0 pg/mL) of the CLEIA kit at least once in nine patients (15.5%) who had PPHA. The PPHA group were older (mean ± standard deviation, 61.3 ± 8.5 vs. 50.5 ± 10.1 years, p < 0.01) and had lower eGFR (60.3 ± 14.0 vs. 82.3 ± 22.8 mL/min/1.73 m2, p < 0.01) than the non-PPHA group. The frequency of postoperative hyperkalemia (maximum serum potassium >5.5 mEq/L) was higher in the PPHA group than in the non-PPHA group (55.6% vs. 8.2%, p < 0.01). In conclusion, a few patients with APA long time after adrenalectomy had unmeasurable PAC using CLEIA. PPHA is likely to develop in patients with APA after adrenalectomy who are older and have impaired renal function. Additionally, PPHA is related to the occurrence of postoperative hyperkalemia.

Neonatal presentation of a patient with Liddle syndrome, South Africa.

Introduction: Liddle syndrome is an autosomal dominantly inherited disorder usually arising from single mutations of the genes that encode for the alpha, beta and gamma epithelial sodium channel (ENaC) subunits. This leads to refractory hypertension, hypokalaemia, metabolic alkalosis, hyporeninaemia and hypoaldosteronism, through over-activation of the ENaC. Case presentation: We describe a 5-day old neonate who presented with severe hypernatraemic dehydration requiring admission to Steve Biko Academic Hospital in South Africa in 2012. Further evaluation revealed features in keeping with Liddle syndrome. Two compound heterozygous mutations located at different subunits encoding the ENaC were detected following genetic sequencing done in 2020. The severe clinical phenotype observed here could be attributed to the synergistic effect of these known pathological mutations, but may also indicate that one of the other variants detected has hitherto undocumented pathological effects. Management and outcome: This child's treatment course was complicated by poor adherence to therapy, requiring numerous admissions over the years. Adequate blood pressure control was achieved only after the addition of amiloride at the end of 2018, which raised the suspicion of an ENaC abnormality. Conclusion: To our knowledge, this is the first Liddle syndrome case where a combined effect from mutations resulted in severe disease. This highlights the importance of early recognition and management of this highly treatable genetic disease to prevent the grave sequelae associated with long-standing hypertension. Whole exome sequencing may assist in the detection of known mutations, but may also unveil new potentially pathological variants. What this study adds: This study highlights the importance of developing a high index of suspicion of tubulopathy such as Liddle syndrome for any child presenting with persistent hypertension associated with hypokalaemic metabolic alkalosis.

Endocrine Disorders in a Newborn with Heterozygous Galactosemia, Down Syndrome and Complex Cardiac Malformation: Case Report.

Down syndrome is the most common chromosomal abnormality diagnosed in newborn babies. Infants with Down syndrome have characteristic dysmorphic features and can have neuropsychiatric disorders, cardiovascular diseases, gastrointestinal abnormalities, eye problems, hearing loss, endocrine and hematologic disorders, and many other health issues. We present the case of a newborn with Down syndrome. The infant was a female, born at term through c-section. She was diagnosed before birth with a complex congenital malformation. In the first few days of life, the newborn was stable. In her 10th day of life, she started to show respiratory distress, persistent respiratory acidosis, and persistent severe hyponatremia, and required intubation and mechanical ventilation. Due to her rapid deterioration our team decided to do a screening for metabolic disorders. The screening was positive for heterozygous Duarte variant galactosemia. Further testing on possible metabolic and endocrinologic issues that can be associated with Down syndrome was performed, leading to hypoaldosteronism and hypothyroidism diagnoses. The case was challenging for our team because the infant also had multiple metabolic and hormonal deficiencies. Newborns with Down syndrome often require a multidisciplinary team, as besides congenital cardiac malformations they can have metabolic and hormonal deficiencies that can negatively impact their short- and long-term prognosis.

ER ribosomal-binding protein 1 regulates blood pressure and potassium homeostasis by modulating intracellular renin trafficking.

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.

[Weigth Loss in a Neonate- A Case of Hypoaldosteronism].

The Neonatal weight loss is a common problem which most physicians who take care of newborns should recognise. The most common reason is insufficient dietary intake. However the reason can also be an underlying disease. Aldosterone insufficiency in neonates is a rare disease and if not treated correctly can be life threatening. It presents with serious electrolytes abnormalities and metabolic acidosis. It is therefore important to distinguish between serious and benign causes of weight loss in neonates.

Acid-Base Imbalance in Pseudohypoaldosteronism Type 1 in Comparison With Type IV Renal Tubular Acidosis.

Context: Pseudohypoaldosteronism type 1 (PHA1) has been treated as a genetic variant of type IV renal tubular acidosis (RTA), leading to the conception that PHA1 develops hyperchloremic acidosis with a normal anion gap (AG). Objective: To delineate the acid-base imbalance in PHA1A (dominant type) and PHA1B (recessive type). Methods: We conducted the following: (1) a retrospective chart review of our patient with PHA1B, and (2) a literature search of PHA1 cases focusing on acid-base balance. The main outcome measures were the incidence and nature of acidosis, including chloride levels and AG. Results: In our patient with PHA1B, 7 salt-wasting episodes were analyzed. Acidosis was ascertained each time, and it was accompanied by hypochloremia except in 1 episode. AG was elevated in 5 episodes, while hyperlacticaemia was present in 3. In the literature, 41 cases of PHA1A and 65 cases of PHA1B have been identified. During salt-wasting crises, acidosis developed in 85% of PHA1A cases and 87% of PHA1B cases. Hypochloremia was present in 69% of PHA1A cases with available data (n = 13) and 54% of eligible PHA1B cases (n = 13), with mean chloride levels of 96 mEq/L and 95 mEq/L, respectively. Increased AG was less frequently reported (14% in PHA1A and 44% in PHA1B). Conclusions: Patients with PHA1 frequently presented with metabolic acidosis. However, hyperchloremia may not be a universal finding, whereas hypochloremia and increased AG may occur in a substantial proportion of the patients.

Clinical manifestations and associated factors in acquired hypoaldosteronism in endocrinological practice.

Introduction: Hypoaldosteronism can be congenital or acquired, isolated or part of primary adrenal insufficiency, and caused by an aldosterone deficit, resistance, or a combination of both. Reduced mineralocorticoid action can induce a decrease in urine K+ and H+ excretion and an increase in urine Na+ excretion, leading to hyperkalemia, and/or hyponatremia, often combined with metabolic acidosis. We aimed to characterize the clinical manifestations of hypoaldosteronism, and their associated factors. Methods: Retrospective analysis of 112 episodes of hypoaldosteronism diagnosed in 86 adult patients from 2012-2019 by the Endocrinology and Nutrition Department of a tertiary hospital. The frequency of hyperkalemia, hypovolemic hyponatremia (HH) and metabolic acidosis (MA), and their associated factors were evaluated. Results: Patients had a median age of 77 [65 - 84], 55.4% were male. 94.6% cases showed hyperkalemia, 54.5% HH, and 60.3% MA. The mean serum K+ of all cases was 5.4 ± 0.5 mmol/L, Na+: 132.1 ± 6.3 mmol/L, HCO3: 22.6 ± 3.3 mmol/L. Hypoaldosteronism was isolated in the majority of cases: only 6/112 (5%) had primary adrenal insufficiency. Hypovolemia was associated with hyponatremia and a more florid clinical presentation. HH was associated with a combined presence of aldosterone-lowering and mineralocorticoid resistance factors. MA was associated with the presence of mineralocorticoid resistance factors. Conclusions: Hypoaldosteronism in adult endocrinological clinical practice is primarily isolated, and acquired. It predisposes not only to the development of hyperkalemia and MA, but also to that of HH. Hypoaldosteronism must be considered in the differential diagnosis of HH with urinary sodium wasting.

Isolated hypoaldosteronism managed by DOCP in a dog with chronic kidney disease and hypercortisolism.

A 13-year-old spayed female Schnauzer dog with chronic kidney disease (CKD; International Renal Interest Society stage 2, non-proteinuric, normotensive), diabetes mellitus, hypercortisolism and myxomatous mitral valve degeneration (American College of Veterinary Internal Medicine stage B2) presented with electrolyte imbalance that had progressed to hyperkalaemia and hyponatremia, with a sodium to potassium (Na:K) ratio of 19.6. Cortisol levels after the adrenocorticotropic hormone stimulation test were within the therapeutic range, but aldosterone levels were below the reference range; hence, isolated hypoaldosteronism was diagnosed. After administration of deoxycorticosterone pivalate (DOCP), the electrolyte imbalance improved with a Na:K ratio of 27.7. This is the first report of the management of isolated hypoaldosteronism and hypercortisolism using trilostane and DOCP in a dog. This case highlights the importance of recognizing isolated hypoaldosteronism after long-term treatment with trilostane in a canine patient with CKD.

Identification of a Novel CYP11B2 Variant in a Family with Varying Degrees of Aldosterone Synthase Deficiency.

Isolated aldosterone synthase deficiency is a rare autosomal recessive disorder caused by pathogenic variants in CYP11B2, resulting in impaired aldosterone synthesis. We report on a neonate with isolated aldosterone synthase deficiency caused by a novel homozygous CYP11B2 variant Chr8:NM_000498.3:c.400G>A p.(Gly134Arg). The patient presented shortly after birth with severe signs of aldosterone deficiency. Interestingly, segregation analysis revealed that the patient's asymptomatic father was also homozygous for the CYP11B2 variant. Biochemical evaluation of the father indicated subclinical enzyme impairment, characterized by elevated aldosterone precursors. Apparently, this homozygous variant led to different clinical phenotypes in two affected relatives. In this manuscript we elaborate on the performed biochemical and genetic work-up and describe potential pitfalls of CYP11B2 sequencing due to its homology to CYP11B2.

A 3-Year-Old Boy with an Xp21 Deletion Syndrome: A Case Report.

BACKGROUND: Chromosome Xp21 deletion syndrome is a rare X-linked recessive defect that occurs as a result of multiple gene deletions, including Glycerol kinase (GK) and its neighboring genes, dystrophin, which causes Duchenne muscular dystrophy (DMD), and NR0B1, which causes congenital adrenal hypoplasia (CAHhttps://www.omim.org/entry/300200). Patients usually present with glycerol kinase deficiency, congenital adrenal hypoplasia, Duchenne muscular dystrophy, hyperglycerolemia, and glyceroluria, associated with DMD and/or CAH, growth failure, myopathy, osteoporosis, mental retardation, and psychomotor retardation. CASE PRESENTATION: Herein, we report a 3-year- old boy from Iraq who had bloody diarrhea, food intolerance and abdominal cramp, adrenal insufficiency, recurrent fevers, tuberculosis (TB) infection, cervical abscess, oral thrush, cervical and mediastinal lymphadenopathies, developmental delay, and undescended testis. His parents are non-consanguine and had no family history of diseases. Next generation sequencing demonstrated a hemizygote deletion in chromosome X. CONCLUSION: Loss of a large part of the X-chromosome most likely can explain the clinical findings of this patient. Contiguous gene deletion syndrome in Xp21 should be considered after diagnosing adrenal insufficiency to treat metabolic complications efficiently.

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.