The β3-AR agonist BRL37344 ameliorates the main symptoms of X-linked nephrogenic diabetes insipidus in the mouse model of the disease

X-linked nephrogenic diabetes insipidus (X-NDI) is a rare congenital disease caused by inactivating mutations of the vasopressin type-2 receptor (AVPR2), characterized by impaired renal concentrating ability, dramatic polyuria, polydipsia and risk of dehydration. The disease, which still lacks a cure, could benefit from the pharmacologic stimulation of other GPCRs, activating the cAMP-intracellular pathway in the kidney cells expressing the AVPR2. On the basis of our previous studies, we here hypothesized that the β3-adrenergic receptor could be such an ideal candidate. We evaluated the effect of continuous 24 h stimulation of the β3-AR with the agonist BRL37344 and assessed the effects on urine output, urine osmolarity, water intake and the abundance and activation of the key renal water and electrolyte transporters, in the mouse model of X-NDI. Here we demonstrate that the β3-AR agonism exhibits a potent antidiuretic effect. The strong improvement in symptoms of X-NDI produced by a single i.p. injection of BRL37344 (1 mg/kg) was limited to 3 h but repeated administrations in the 24 h, mimicking the effect of a slow-release preparation, promoted a sustained antidiuretic effect, reducing the 24 h urine output by 27%, increasing urine osmolarity by 25% and reducing the water intake by 20%. At the molecular level, we show that BRL37344 acted by increasing the phosphorylation of NKCC2, NCC and AQP2 in the renal cell membrane, thereby increasing electrolytes and water reabsorption in the kidney tubule of X-NDI mice. Taken together, these data suggest that human β3-AR agonists might represent an effective possible treatment strategy for X-NDI.

Antidiuretic hormone deficiency secondary to inactive hydrocephalus: a case report

BACKGROUND

Diabetes insipidus is a syndrome characterized by polyuria, which is almost always associated with polydipsia. The most frequent cause is central diabetes insipidus, which is the result of an inadequate secretion of the antidiuretic hormone, and diagnosis involves differentiating it from other causes of polyuria and polydipsia.

CASE PRESENTATION

Here, we present a clinical case of a previously healthy 13-year-old Nepali boy, who, in December 2022, was found to have intense polydipsia accompanied by polyuria. He had bilateral lower limb weakness at the time of presentation. Biochemical evaluation demonstrated raised serum sodium (181 mEq/L), serum creatinine (78 μmol/L), and serum uric acid (560 μmol/L) with suppressed serum potassium (2.7 mEq/L), which was the major concern to the clinicians. Further laboratory workup revealed an increased serum osmolarity (393.6 mOsm/kg) with reduced urine osmolarity (222.7 mOsm/kg). On contrast magnetic resonance imaging of the brain, a thick-walled third ventricular cyst with bilateral foramen obstruction, thin membrane-like structure at top of aqueduct of Sylvius with gross obstructive hydrocephalus (inactive), and compressed and thinned pituitary gland with no bright spot was observed. The laboratory findings, radiological findings, and case presentation provided the provisional diagnosis of diabetes insipidus due to hydrocephalus and third ventricular cyst.

CONCLUSIONS

Central diabetes insipidus due to hydrocephalus, though rare, can have serious complications including the predilection to develop a deficit of other pituitary hormones. Thus, even if hydrocephalus is dormant with normal intracranial pressure, it must be addressed during investigations of central diabetes insipidus.

An exceptional cause of polyuria-polydipsia syndrome in a 10-year-old boy

Polyuria-polydipsia syndrome is a frequent symptom in pediatrics, primarily attributed to diabetes mellitus. In the context of diabetes insipidus, this syndrome can stem from central or nephrogenic factors. Sjögren's syndrome, an uncommon autoimmune disease in children, can affect multiple organs. Kidney involvement as described in adults is usually related to glomerular or tubular impairment, often linked to distal tubular acidosis. As a kidney involvement during childhood, Sjögren's syndrome has rarely been reported. Hereby, we present the case of Sjögren's syndrome revealed by polyuria-polydipsia syndrome in a 10-year-old boy.

Hypodipsic hypernatremia after long-standing polydipsia in a cat with suspect neonatal head trauma

A 16-month-old neutered male domestic shorthair cat weighing 2.7 kg was referred for further evaluation of acute generalized muscle weakness and paraparesis after a long-standing history of polyuria-polydipsia. The diagnosis of hypodipsic/adipsic hypernatremia relied on the key findings of absent spontaneous drinking despite hypernatremia and a hyperosmolar state (444.8 mOsm/kg, reference interval 280 to 310 mOsm/kg). Brain MRI revealed severe multifocal anatomic anomalies of the rostral calvarium and the forebrain, suggestive of encephaloclastic porencephaly. Involvement of the thalamic and hypothalamic regions could have been responsible for the cat's adipsic hypernatremia. The unique aspects of this case were the rare description of central nervous system disease leading to hypodipsia, and the history of chronic polydipsia before the acute onset of hypodipsia. Key clinical message: Multifocal abnormalities of the forebrain can present with polyuria-polydipsia syndrome, hypodipsia/adipsia, or both, depending on the stage of the disease. This likely happens when the hypothalamic and thalamic regions are affected, since they regulate antidiuretic hormone release and thirst, respectively.

Ketoacidosis, Hypertriglyceridemia and Acute Pancreatitis Induced by Soft Drink Polydipsia in a Patient with Occult Central Diabetes Insipidus

A 21-year-old Japanese man without known diabetes mellitus had abdominal pain. The diagnosis was ketoacidosis and hypertriglyceridemia-induced acute pancreatitis. He had polydipsia and polyuria and had habitually drunk several soft drinks every day for two years. After hospitalization, despite adequate liquid intake, dehydration remained with hypotonic polyuria. Further examinations revealed the coexistence of central diabetes insipidus (CDI), possibly caused by lymphocytic infundibulo-neurohypophysitis, based on anti-rabphilin-3A antibody positivity. Although CDI had been undiagnosed for two years, over-consumption of sugar-rich soft drinks to ease thirst caused ketoacidosis, hypertriglyceridemia, and acute pancreatitis. There are no previous reports of this three-part combination of symptoms caused by CDI.

Role of copeptin in the diagnosis of traumatic neuroendocrine dysfunction

Traumatic neuroendocrine dysfunction may present with diabetes insipidus (DI) or with the syndrome of inappropriate antidiuretic hormone secretion (SIADH). Both these pathologies involve a disturbance in the antidiuretic hormone (ADH) secretion, causing dysnatremias. Diagnosis of posttraumatic ADH dysfunction is hampered by technical difficulties in ADH assessment, and relies mostly on non-specific serum sodium, serum and urine osmolality and diuresis, often leading to misdiagnosis in the acute care setting. Research now focuses on the diagnostic role of copeptin, a peptide secreted together with ADH in an equimolar fashion, and which can be accurately evaluated. Recent studies identified cut-off values of 2.6 pmol/L for baseline copeptin and of 4.9 and 3.8 pmol/L for hypertonic saline infusion and arginine infusion stimulated copeptin, respectively, for the diagnosis of DI in patients with polyuria-polydipsia syndrome. Although SIADH is more difficult to be explored due to its heterogeneity, a ratio of copeptin to urinary sodium below 30 pmol/mmol identifies euvolemic hyponatremia. Exploring the role of copeptin assessment in patients with traumatic brain injury (TBI) in the acute phase may improve their diagnosis accuracy, management and outcome.

Genetic deletion of connexin 37 causes polyuria and polydipsia

The connexin 37 (Cx37) channel is clustered at gap junctions between cells in the renal vasculature or the renal tubule where it is abundant in basolateral cell interdigitations and infoldings of epithelial cells in the proximal tubule, thick ascending limb, distal convoluted tubule and collecting duct; however, physiological data regarding its role are limited. In this study, we investigated the role of Cx37 in fluid homeostasis using mice with a global deletion of Cx37 (Cx37-/- mice). Under baseline conditions, Cx37-/- had ~40% higher fluid intake associated with ~40% lower urine osmolality compared to wild-type (WT) mice. No differences were observed between genotypes in urinary adenosine triphosphate or prostaglandin E2, paracrine factors that alter renal water handling. After 18-hours of water deprivation, plasma aldosterone and urine osmolality increased significantly in Cx37-/- and WT mice; however, the latter remained ~375 mmol/kg lower in Cx37-/- mice, an effect associated with a more pronounced body weight loss despite higher urinary AVP/creatinine ratios compared to WT mice. Consistent with this, fluid intake in the first 3 hours after water deprivation was 37% greater in Cx37-/- vs WT mice. Cx37-/- mice showed significantly lower renal AQP2 abundance and AQP2 phosphorylation at serine 256 than WT mice in response to vehicle or dDAVP, suggesting a partial contribution of the kidney to the lower urine osmolality. The abundance and responses of the vasopressin V2 receptor, AQP3, NHE3, NKCC2, NCC, H+-ATPase, αENaC, γENaC or Na+/K+-ATPase were not significantly different between genotypes. In summary, these results demonstrate that Cx37 is important for body water handling.

Coexistence of craniopharyngioma and meningioma: Two rare cases and literature review

Most of the craniopharyngioma is considered to derive from residual epithelial cells during the craniopharyngeal canal degeneration. Meningioma accounting for the primary intracranial neoplasm is considered to be mainly derived from cells of arachnoid granulations. Nevertheless, rare cases show coexistence of craniopharyngioma and meningioma.Case 1: A 43-year-old male patient referred to the hospital due to paroxysmal headache combined with blurred vision for 1 month. On physical examination, the visual acuity of left eye was poorer than that of the right eye. The visual acuity of the right eye near the nasal part showed defect.MRI and pathological examination were performed. The patient received intracranial tumor resection. After surgery, the patient showed hormone disorder, followed by corresponding treatment. However, the patient was lost in the 6-month follow-up.Case 2: The 64-year-old male patient presented to our department due to decline of visual acuity within 1 year combined with polydipsia (5,000 ml per day), polyuria and fatigue for 6 months. On physical examination, the bilateral visual acuity showed decline, especially the temporal part which was nearly hemiscotosis. MRI was performed. The adamantinomatous craniopharyngioma was diagnosed with the HE staining findings. The patient received intracranial resection. After surgery, the patient was in a deep coma condition, and was lost in the follow-up.In this case study, we presented 2 patients with coexistence of craniopharyngioma and meningioma. In addition, a complete literature review was carried out to illustrate the studies on coexistence of craniopharyngioma and meningioma. Meanwhile, we tried to explain the possible mechanisms for such condition.

Primary polydipsia: Update

In primary polydipsia pathologically high levels of water intake physiologically lower arginine vasopressin (AVP) secretion, and in this way mirror the secondary polydipsia in diabetes insipidus in which pathologically low levels of AVP (or renal responsiveness to AVP) physiologically increase water intake. Primary polydipsia covers several disorders whose clinical features and significance, risk factors, pathophysiology and treatment are reviewed here. While groupings may appear somewhat arbitrary, they are associated with distinct alterations in physiologic parameters of water balance. The polydipsia is typically unrelated to homeostatic regulation of water intake, but instead reflects non-homeostatic influences. Recent technological advances, summarized here, have disentangled functional neurocircuits underlying both homeostatic and non-homeostatic physiologic influences, which provides an opportunity to better define the mechanisms of the disorders. We summarize this recent literature, highlighting hypothalamic circuitry that appears most clearly positioned to contribute to primary polydipsia. The life-threatening water imbalance in psychotic disorders is caused by an anterior hippocampal induced stress-diathesis that can be reproduced in animal models, and involves phylogenetically preserved pathways that appear likely to include one or more of these circuits. Ongoing translational neuroscience studies in these animal models may potentially localize reversible pathological changes which contribute to both the water imbalance and psychotic disorder.

Central diabetes insipidus in children: Diagnosis and management

Central diabetes insipidus (CDI) is a complex disorder in which large volumes of dilute urine are excreted due to arginine-vasopressin deficiency, and it is caused by a variety of conditions (genetic, congenital, inflammatory, neoplastic, traumatic) that arise mainly from the hypothalamus. The differential diagnosis between diseases presenting with polyuria and polydipsia is challenging and requires a detailed medical history, physical examination, biochemical approach, imaging studies and, in some cases, histological confirmation. Magnetic resonance imaging is the gold standard method for evaluating the sellar-suprasellar region in CDI. Pituitary stalk size at presentation is variable and can change over time, depending on the underlying condition, and other brain areas or other organs - in specific diseases - may become involved during follow up. An early diagnosis and treatment are preferable in order to avoid central nervous system damage and the risk of dissemination of germ cell tumor, or progression of Langerhans Cell Histiocytosis, and in order to start treatment of additional pituitary defects without further delay. This review focuses on current diagnostic work-up and on the role of neuroimaging in the differential diagnosis of CDI in children and adolescents. It provides an update on the best approach for diagnosis - including novel biochemical markers such as copeptin - treatment and follow up of children and adolescents with CDI; it also describes the best approach to challenging situations such as post-surgical patients, adipsic patients, patients undergoing chemotherapy and/or in critical care.

Acquired forms of central diabetes insipidus: Mechanisms of disease

Most cases of acquired central diabetes insipidus are caused by destruction of the neurohypophysis by: 1) anatomic lesions that destroy the vasopressin neurons by pressure or infiltration, 2) damage to the vasopressin neurons by surgery or head trauma, and 3) autoimmune destruction of the vasopressin neurons. Because the vasopressin neurons are located in the hypothalamus, lesions confined to the sella turcica generally do not cause diabetes insipidus because the posterior pituitary is simply the site of the axon terminals that secrete vasopressin into the bloodstream. In addition, the capacity of the neurohypophysis to synthesize vasopressin is greatly in excess of the body's needs, and destruction of 80-90% of the hypothalamic vasopressin neurons is required to produce diabetes insipidus. As a result, even large lesions in the sellar and suprasellar area generally are not associated with impaired water homeostasis until they are surgically resected. Regardless of the etiology of central diabetes insipidus, deficient or absent vasopressin secretion causes impaired urine concentration with resultant polyuria. In most cases, secondary polydipsia is able to maintain water homeostasis at the expense of frequent thirst and drinking. However, destruction of the osmoreceptors in the anterior hypothalamus that regulate vasopressin neuronal activity causes a loss of thirst as well as vasopressin section, leading to severe chronic dehydration and hyperosmolality. Vasopressin deficiency also leads to down-regulation of the synthesis of aquaporin-2 water channels in the kidney collecting duct principal cells, causing a secondary nephrogenic diabetes insipidus. As a result, several days of vasopressin administration are required to achieve maximal urine concentration in patients with CDI. Consequently, the presentation of patients with central diabetes insipidus can vary greatly, depending on the size and location of the lesion, the magnitude of trauma to the neurohypophysis, the degree of destruction of the vasopressin neurons, and the presence of other hormonal deficits from damage to the anterior pituitary.

A Rare High-Grade Glioma with a Histone H3 K27M Mutation in the Hypothalamus of an Adult Patient

BACKGROUND

Diffuse midline glioma H3 K27M mutant is a new tumor entity described in the revised 2016 World Health Organization classification. It is most frequently observed in children and develops in midline structures, including the brainstem, thalamus, and spine. We describe a rare diffuse midline glioma with an H3 K27M mutation arising in the hypothalamus of an adult.

CASE DESCRIPTION

A 27-year-old woman was admitted to our department complaining of amenorrhea, polydipsia, and diuresis for the previous 3 months, and headache and lethargy for approximately 10 days. Computed tomography scan showed an oval isodense solid mass extending from the pituitary toward the suprasellar cistern. A gadolinium-enhanced magnetic resonance imaging (MRI) showed a strongly heterogeneous enhanced solid lesion and nonenhanced cystic lesion. The patient underwent surgery and chemoradiotherapy with temozolomide. Histologic and immunohistochemical analyses revealed H3 K27M-mutant diffuse midline glioma. The patient underwent another resection for a recurrent tumor 5 months after the first surgery. Three months after the second operation, the patient relapsed, with MRI revealing spinal cord and meningeal metastases; she died shortly afterward.

CONCLUSIONS

Diffuse midline glioma with an H3 K27M mutation occurring in the hypothalamus of an adult is rare but should be considered in differential diagnoses. Because histone H3 K27M mutations are associated with aggressive clinical behavior and poor prognosis, molecular analyses should be used to determine the clinical and histopathologic features of such tumors. This will contribute to developing targeted drugs and gene therapy going forward.

Characterization of Novel Nonobese Type 2 Diabetes Rat Model with Enlarged Kidneys

A variety of animal models of diabetes mellitus (DM) are required to study the genetics and pathophysiology of DM. We established a novel rat strain showing nonobese type 2 diabetes with enlarged kidneys from the LEA.PET-pet congenic strain and named it Diabetes with Enlarged Kidney (DEK). The body growth of DEK affected rats was similar to that of normal rats before the development of DM but was attenuated with the deterioration of DM. There was a marked difference in the etiology of DEK by gender: DM phenotypes including polyuria, polydipsia, and hyperglycemia (nonfasting blood glucose over 300 mg/dl) were found in male rats aged over 10 weeks but not in female rats. The cumulative incidence of DM in DEK males at the age of 30 weeks was 44.8%. Oral glucose tolerance tests showed glucose intolerance and decreased insulin secretion in response to glucose loading in affected males, features which were exacerbated with age. Affected males exhibited disorganized architecture of pancreatic islets, decreased numbers of β cells, and markedly decreased expression of insulin, despite no pathological findings of hemorrhage or infiltration of inflammatory cells in the pancreatic islet. Age-related islet fibrosis appeared similar in normal and affected males. Affected males also showed enlarged kidneys with dilation of renal tubules in both the cortex and medulla, but no obvious glomerular lesions typical of diabetic nephropathy (DN) at the age of 30 weeks. Plasma levels of urea nitrogen and creatinine were normal, but hypoalbuminemia was detected. These pathophysiological features in affected males indicated that their renal function was almost maintained despite severe DM. Taken together, these findings indicate that the affected males of the DEK strain are a novel nonobese type 2 diabetes rat model useful for studying the mechanisms underlying β cell loss and identifying genetic factors protective against DN.

Gastric liposarcoma in a patient with severe obesity

Liposarcoma is the most common soft tissue sarcoma in adults. Predominant locations are the limbs and retroperitoneum. Intra-abdominal liposarcoma represents only 2% of all cases and visceral location is exceptional. Gastric liposarcoma is extremely rare, with fewer than 20 cases reported. The treatment of choice is wide en-bloc surgical resection. If the tumour arises in the area of the cardia, resection involves resection of the proximal stomach as well as the distal oesophagus. Traditional reconstruction with oesophagogastrostomy often leads to troublesome reflux. We report a case of gastric liposarcoma arising in the gastro-oesophageal junction in a severely obese patient.

Diabetes in Childhood and Adolescence

BACKGROUND

The incidence of type 1 diabetes mellitus in childhood and adolescence is steadily rising and now stands at 22.9 new cases per year per 100 000 persons up to age 15.

METHODS

This review is based on pertinent publications retrieved by a selective literature search, with special attention to the current German S3 guideline on diabetes in childhood and adolescence.

RESULTS

Polydipsia, polyuria, and weight loss are the characteristic presenting symptoms of diabetes mellitus. The acutely presenting patient needs immediate stabilization because of the danger of rapid metabolic decompensation (risk of keto - acidosis, 21.1%). Long-term insulin therapy can be delivered either by subcutaneous injection or by an insulin pump. The goals of treatment are the near-normalization of glucose metabolism (HbA1c <7.5%), the avoidance of acute complications (hypoglycemia and ketoacidosis), the reduction of diabetes-specific sequelae (retinopathy, nephropathy, neuropathy, hypertension, and hyperlipidemia), unrestricted participation in age-appropriate everyday activities, and normal physical and psychosocial development. Children and adolescents with diabetes need individualized treatment with frequent adjustments and holistic overall care so that these goals can be effectively met.

CONCLUSION

Every physician must be able to diagnose the initial presentation of diabetes and to initiate the first steps in its management. The patient should be referred as soon as possible to a diabetes team that has experience in the treatment of children and adolescents.

Erdheim-Chester disease: a rare histiocytosis (case report and review of the literature)

We report a case of Erdheim-chester disease, a rare non-langerhans histiocytosis revealed by polydipsia-polyuria syndrome in a 26 years old woman, trated by interferon with a good response.

Extended honeymoon period in a type 1 diabetic child by Iranian Traditional Medicine treatments, a case report

We present a 4-year-old newly diagnosed T1DM boy who presented with sever polyuria and polydipsia and HbA1C of 9.3%. Coincident with onset of ITM program insulin doses were tapered and the baby got free from insulin soon. Only three months after traditional anti-diabetic medications, his HbA1C improved to 5.8%.

Type 1 diabetes mellitus and Graves' disease in Down's syndrome--a rare combination

BACKGROUND

Autoimmune diseases including thyroid. disorders, type 1 diabetes and celiac disease are commoner in persons with Down's syndrome compared with the general population. Coexistent type 1 diabetes and hyperthyroidism in Down's syndrome is however not commonly reported in literature.

OBJECTIVE

To report a case of a lady presenting with Graves' disease and type 1 diabetes at the same time.

CLINICAL PRESENTATION

We report the case of a 22- year-old lady with Down's syndrome who presented with weight loss, polyuria and polydipsia. Physical examination revealed typical dysmorphicfacies of Down's syndrome and a goitre. Laboratory data revealed hyperglycaemia (random plasma glucose-331 mg/dl). She also had biochemical evidence in keeping with hyperthyroidism and markedly elevated thyroid peroxidase antibodies (>1087.0 IU/ml). She improved after rehydration, insulin therapy and antithyroid drugs.

CONCLUSION

Coexisting autoimmune diseases may present in patients with Down's syndrome. We advocate for routine screening for diabetes and thyroid dysfunction in ersons with Down's syndrome.

History before diagnosis in childhood craniopharyngioma: associations with initial presentation and long-term prognosis

OBJECTIVE

Childhood craniopharyngiomas (CP) are often diagnosed after a long duration of history (DOH). Tumor size, hypothalamic involvement (HI), and obesity are associated with reduced overall survival (OS) and functional capacity (FC). The effect of DOH and specific symptoms in history on presentation at initial diagnosis and long-term prognosis are unknown.

DESIGN

Retrospective analysis of patients' records and prospective longitudinal follow-up.

METHODS

Histories of 411 CP patients recruited in HIT Endo, KRANIOPHARYNGEOM 2000 were retrospectively evaluated for DOH, symptoms, and characteristics. The effect of specific manifestations and DOH on clinical presentation and tumor characteristics at time of initial CP diagnosis and long-term outcome were analyzed. Main outcome measures were 10-year OS and progression-free survival (PFS), FC, and BMI during longitudinal follow-up.

RESULTS

Median DOH was 6 months (range: 0.1-108 months) and correlated with age at diagnosis. Tumor size, HI, degree of resection, and BMI at diagnosis were not related to DOH. In multivariate analysis adjusted for age at diagnosis, only hydrocephalus was found to have a relevant influence on DOH. Visual and neurological deficits were associated with larger initial tumor size and impaired 10-year OS. Weight gain and growth failure were observed with longest DOH. PFS and FC were not related to any specific symptom. Endocrine deficits at diagnosis were associated with long DOH.

CONCLUSIONS

CP is frequently diagnosed after long DOH, especially in older children. However, DOH was not associated with tumor size, HI, survival, or FC. Visual and neurological deficits necessitate rapid diagnostic workup.

[A practical algorithm for polydipsia in children]

There is a lack of consent on a clinical diagnostic work-up for children with polydipsia. This can result in a delay in diagnosis in some children and unnecessary investigations in others. We describe three children who presented with polydipsia. Two of them were diagnosed with psychogenic polydipsia and one with central diabetes insipidus. We discuss the differential diagnosis and relevant clinical signs before going on to propose a clinical diagnostic algorithm that can be used in children with polydipsia. A systematic diagnostic work up for children with polydipsia helps to differentiate between those in whom polydipsia is unlikely to have a somatic cause and those where a water deprivation-test is indicated. A water deprivation test in children is an invasive procedure and should be performed by a paediatric endocrinologist or nephrologist.

A study on hypoglycaemic health care function of Stigma maydis polysaccharides

The objective of this paper was to study the therapeutic effect of Stigma maydis polysaccharides in diabetic mice. Mouse models of types 1 and 2 diabetes were established. The body weight, food intake, water intake as well as blood sugar level and glucose tolerance of mice were measured. Stigma maydis polysaccharides can improve the symptoms of weight loss and polydipsia in diabetic mice, and had an obvious antagonistic effect on alloxan-induced hyperglycaemia. The glucose tolerance test also showed that the Stigma maydis polysaccharides had very good effects on suppression and prevention of acute hyperglycaemia. Stigma maydis polysaccharides have some improvement effect on alloxan-induced types 1 and 2 diabetes.

[Primary distal renal tubular acidosis in children in the South of Tunisia: study of 15 cases]

BACKGROUND

primary distal renal tubular acidosis in children (RTA) is characterized by metabolic acidosis due to defect in urinary excretion of hydrogen (H+) in the distal tubular.

AIM

To report the epidemiological, clinical, therapeutic and evolutionary of distal RTA in our patients.

PATIENTS AND METHODS

We conducted a retrospective study of all cases of distal RTA collected in the department of pediatrics of Hedi Chaker University hospital in the south of Tunisia, during a period of 23 years (1988-2010). We studied the epidemiological, clinical, biological, evolutionary and therapeutic data.

RESULTS

During the study period 15 cases of distal RTA were collected. The average age was 6 months (1 month -2 years). Most common presenting symptoms were vomiting (8cases), failure to thrive (4cases), lack of appetite, polyuria-polydipsia syndrome (1case) and urinary infection (2cases). The clinical examination showed staturoponderal delay (9 cases), dehydration (6 cases), signs of rickets (3 cases) and polyuria (10 cases). Biological data showed high urine pH in the presence of metabolic acidosis in 11 cases, hypokalaemia in 10 cases and hypercalciuria in all cases. Urine acidification test with ammonium chloride was performed in 4 cases, the urinary pH was always higher than 5.5 in all cases. Ammoniuria performed in 9 cases was less than 40mmol/l. Radiological investigation objectified a nephrocalcinosis in fourteen patients and signs of rickets in three cases. Deafness was found in three patients. Genetic study performed in two cases showed mutation of ATP6V1B1 gene. The medical treatment involved an alkali load. Long-term outcome was favorable in 7 cases.

CONCLUSION

The distal renal tubular acidosis is a rare pathology in our country but probably under diagnosed. The clinical gravity of this disease and the risk of evolution towards the terminal renal insufficiency justify an antenatal diagnosis to establish a neonatal management or propose a therapeutic interruption of the pregnancy if the distal RTA is associated with a severe pathology.

Increased drinking following social isolation rearing: implications for polydipsia associated with schizophrenia

Primary polydipsia, excessive drinking without known medical cause, is especially associated with a diagnosis of schizophrenia. We used animal models of schizophrenia-like symptoms to examine the effects on schedule-induced polydipsia: post-weaning social isolation rearing, subchronic MK-801 treatment (an NMDA-receptor antagonist) or the two combined. Male, Sprague-Dawley rats reared in groups or in isolation beginning at postnatal day 21 were further divided to receive subchronic MK-801 (0.5 mg/kg twice daily) or saline for 7 days beginning on postnatal day 62. Following a 4-day withdrawal period, all groups were trained on a schedule-induced polydipsia paradigm. Under food-restriction, animals reared in isolation and receiving food pellets at 1-min intervals developed significantly more drinking behavior than those reared with others. The addition of subchronic MK-801 treatment did not significantly augment the amount of water consumed. These findings suggest a predisposition to polydipsia is a schizophrenia-like behavioral effect of post-weaning social isolation.

Inhibition of natriuresis in median eminence polydipsia: effects after intake of diets with different osmolalities and after hypertonic NaCl administration

Lesions in the hypothalamic median eminence (ME) induce polydipsia and polyuria in male rats. A first experiment was designed to examine the effect of salt consumption (standard 0.25 percent Na+ vs. low-salt 0.04 percent Na+ diet) on the fluid-electrolytic balance (plasma sodium, urinary sodium excretion, urine osmolality) and water intake of ME polydipsic animals. In the first 6 h post-surgery, the natriuretic response was higher in ME-lesioned animals than in control groups. At 24 h post-surgery, however, less sodium was excreted by ME rats fed with a standard salt diet (ME/SS), despite showing no decrease in salt intake, and they evidenced an increase in plasma sodium concentration and water intake. Urine osmolality was significantly higher in control animals than in either ME-lesioned group. In experiment 2, hypertonic NaCl administration (2 ml/2M) increased the polydipsic behavior of ME-lesioned but not control rats (day 2). Animals deprived of food/salt showed a significant reduction (on day 2) in the initial (day 1) polydipsia, which increased on day 3 when the animals had access to a standard-salt diet. These results suggest that the reduced natriuretic response and the consequent sodium retention observed in ME animals may exacerbate the hydromineral imbalance of this polydipsic syndrome.

[Central diabetes insipidus: diagnosis and management]

Central diabetes insipidus (CDI) is caused by deficient secretion of antidiuretic hormone (ADH) due to different conditions that can affect the hypothalamic neurons. It results in an inability to retain normal quantities of free water, which leads to polyuria, including at night, and polydipsia. In adults, it is mostly due to the "idiopathic" form or present after pituitary surgery or a traumatic brain injury. In rare cases, an underlying systemic disease is found. The diagnosis of CDI is based on the water deprivation test. Pituitary MRI and specific clinical and biological work-up are recommended to precise etiology. Treatment of choice is desmopressin, a synthetic analogue of the endogenous ADH hormone. A multidisciplinary team generally provides management and monitoring of CDI.

A rare cause of goiter: Langerhans cell histiocytosis of the thyroid

Goiter is a very common clinical problem; however, Langerhans cell histiocytosis (LCH) with thyroid involvement that presents as a goiter is very rare. In this article, we report one case of thyroid LCH. An 18-year-old male patient presented with goiter, polyuria, polydipsia, and lymphadenectasis of the neck, and LCH was confirmed by a lymph node biopsy and pathological investigation. Without a thyroidectomy, the goiter shrank after nine cycles of chemotherapy. In addition, we summarize the reported thyroid LCH cases in the literature from the last 10 years. LCH usually involves other organs, such as the lungs, bones, skin, pituitary gland, and lymph nodes. Thyroid LCH is more common in adults than in children, and it may coexist with a thyroid carcinoma. Without any unique thyroid manifestations, either clinically or by imaging, it is difficult to distinguish thyroid LCH from other thyroid diseases. Pathology is the gold standard for the diagnosis of LCH. A fine needle aspiration biopsy (FNAB) may help to diagnosis LCH, although sometimes it leads to misdiagnosis. Chemotherapy is recommended for multi-system LCH. Younger patients with widespread disease or who are non-responsive to chemotherapy have poor outcomes.

Polyuric-polydipsic syndrome in a pediatric case of non-glucocorticoid remediable familial hyperaldosteronism

Familial hyperaldosteronism (FH) encompasses 3 types of autosomal dominant hyperaldosteronisms leading to inheritable hypertension. FH type II (FH-II), undistinguishable from sporadic hyperaldosteronism, represents the most frequent cause of inheritable hypertension and is believed to only manifest in adults. FH-III is a severe variety of PA resistant to pharmacotherapy and recently demonstrated to be caused by mutations in the gene encoding the potassium channel KCNJ5. In this report, we describe a FH pediatric patient, remarkable both for age at onset and unusual presentation: a two-years old girl with polyuric-polydipsic syndrome and severe hypertension, successfully treated with canrenone and amiloride. The girl had severe hypertension, hypokalemia, hypercalciuria, suppressed renin activity, high aldosterone, and unremarkable adrenal imaging. FH type I was ruled out by glucocorticoid suppression test, PCR test for CYP11B1/CYP11B2 gene, and urinary 18-oxo-cortisol and 18-hydroxy-cortisol excretion, which was in FH-II range. In spite of a clear-cut FH-II phenotype, the girl and her mother were found to harbor a FH-III genotype with KCNJ5 mutation (c.452G>A). Treatment with canrenone was started, resulting in prompt normalization of electrolytes and remission of polyuric-polydypsic syndrome. The addition of amiloride led to a complete normalization of blood pressure. This report expands the phenotypic spectrum of FH-III to a milder end, mimiking FH-II phenotype demonstrating that pharmacotherapy may be effective. This also implies that FH-II/III should be considered in the differential diagnosis of hypertensive children and, perhaps, that the offspring of patients with hyperaldosteronism should be screened for hypertension.