Copeptin; utility in paediatric patients with hyponatraemia

Introduction Copeptin concentrations are a useful component of the diagnostic work-up of paediatric patients with polyuria and polydipsia but the value of measuring copeptin in patients with hyponatraemia is less clear. Case Reports We report 5 children with hyponatraemia in the context of different underlying pathologies. Copeptin concentrations were elevated in 4 cases (13.7, 14.4, 26.1, 233pmol/L; reference range 2.4 – 8.6pmol/L) suggesting that non-osmoregulated vasopressin release (syndrome of inappropriate antidiuretic diuretic hormone or SIADH) was the underlying mechanism for the low sodium levels. In one of the patients there was an underlying diagnosis of Schaaf-Yang syndrome (MAGEL 2 gene mutation) with a clinical picture suggestive of dysregulated vasopressin production with inappropriately high and then low copeptin release. In one hyponatraemic patient, low copeptin concentrations indicated that non-osmoregulated AVP release was not the cause of hyponatraemia and oliguria. Discussion Copeptin measurement did not influence management acutely but helped to clarify the mechanism leading to hyponatraemia when the result was available. Relatively high and low copeptin concentrations in association with hypo and hypernatraemia indicates dysregulated vasopressin production in Schaaf-Yang syndrome. Profound copeptin elevation may be a clue to underlying sepsis.

Concurrent central diabetes insipidus and cerebral salt wasting disease in a post-operative case of craniopharyngioma: a case report

Background Water and electrolyte disorders commonly encountered in children post-surgery involving hypothalamus and posterior pituitary, are central diabetes insipidus, syndrome of inappropriate secretion of anti-diuretic hormone and cerebral salt wasting disease. Delayed diagnosis and inadequate management of such cases may lead to worsened neurological outcomes with a high mortality rate. Case presentation Here we report the case of a 7-year-old girl who underwent surgical resection of a craniopharyngioma, following which she initially developed central diabetes insipidus. However, later on in the course of her illness she developed symptomatic hyponatremia with natriuresis which was diagnosed to be due to cerebral salt wasting disease. This combination of central diabetes insipidus and cerebral salt wasting syndrome is a rare occurrence and poses a diagnostic challenge. Diagnosis and management can be even more difficult when these conditions precede or coexist with each other. Conclusion In such cases development of hyponatremia should always prompt consideration of unusual causes like cerebral salt wasting disease in addition to the classically described syndrome of inappropriate secretion of anti-diuretic hormone. Hence, a thorough knowledge of these disorders along with intensive monitoring of fluid and sodium status is critical for timely diagnosis and management of these patients.

Hyponatremia: It’s in the Eye of the Beholder: Pitfalls in the Diagnosis and Treatment of SIADH with Desalination due to Herpes Zoster Ophthalmicus (HZO)

Herpes Zoster Ophthalmicus (HZO) is a rare cause of SIADH (Syndrome of Inappropriate Anti-Diuretic Hormone secretion). It occurs when herpesvirus type 3 activation presents in the first division, or ophthalmic division of the trigeminal nerve.

Identification of cells expressing Calcitonins A and B, PDF and ACP in Locusta migratoria using cross-reacting antisera and in situ hybridization

This work was initiated because an old publication suggested that electrocoagulation of four paraldehyde fuchsin positive cells in the brain of Locusta migratoria might produce a diuretic hormone, the identity of which remains unknown, since none of the antisera to the various putative Locusta diuretic hormones recognizes these cells. The paraldehyde fuchsin positive staining suggests a peptide with a disulfide bridge and the recently identified Locusta calcitonins have both a disulfide bridge and are structurally similar to calcitonin-like diuretic hormone. In situ hybridization and antisera raised to calcitonin-A and -B were used to show were these peptides are expressed in Locusta. Calcitonin-A is produced by neurons and neuroendocrine cells that were previously shown to be immunoreactive to an antiserum to pigment dispersing factor (PDF). The apparent PDF-immunoreactivity in these neurons and neuroendocrine cells is due to crossreactivity with the calcitonin-A precursor. As confirmed by both an PDF-precursor specific antiserum and in situ hybridisation, those calcitonin-A expressing cells do not express PDF. Calcitonin B is expressed by numerous enteroendocrine cells in the midgut as well as the midgut caeca. A guinea pig antiserum to calcitonin A seemed quite specific as it recognized only the calcitonin A expressing cells. However, rabbit antisera to calcitonin-A and-B both crossreacted with neuroendocrine cells in the brain that produce ACP, this is almost certainly due to the common C-terminal dipeptide SPamide that is shared between Locusta calcitonin-A, calcitonin-B and ACP.

Unveiling the sensory and interneuronal pathways of the neuroendocrine connectome in Drosophila

Neuroendocrine systems in animals maintain organismal homeostasis and regulate stress response. Although a great deal of work has been done on the neuropeptides and hormones that are released and act on target organs in the periphery, the synaptic inputs onto these neuroendocrine outputs in the brain are less well understood. Here, we use the transmission electron microscopy reconstruction of a whole central nervous system in the Drosophila larva to elucidate the sensory pathways and the interneurons that provide synaptic input to the neurosecretory cells projecting to the endocrine organs. Predicted by network modeling, we also identify a new carbon dioxide-responsive network that acts on a specific set of neurosecretory cells and that includes those expressing corazonin (Crz) and diuretic hormone 44 (Dh44) neuropeptides. Our analysis reveals a neuronal network architecture for combinatorial action based on sensory and interneuronal pathways that converge onto distinct combinations of neuroendocrine outputs.

A population of neurons that produce hugin and express thediuretic hormone 44 receptorgene projects to the corpora allata inDrosophila melanogaster

The corpora allata (CA) are essential endocrine organs that biosynthesize and secrete the sesquiterpenoid hormone, namely juvenile hormone (JH), to regulate a wide variety of developmental and physiological events in insects. Previous studies had demonstrated that the CA are directly innervated with neurons in many insect species, implying the innervations to be important for regulating JH biosynthesis in response to internal physiology and external environments. While this is also true for the model organism,Drosophila melanogaster, which neurotransmitters are produced in the CA-projecting neurons are yet to be clarified. In this study onD. melanogaster, we aimed to demonstrate that a subset of neurons producing the neuropeptide hugin, the invertebrate counterpart of the vertebrate neuromedin U, directly projects to the adult CA. A synaptic vesicle marker in the hugin neurons was observed at their axon termini located on the CA, which were immunolabeled with a newly-generated antibody to the JH biosynthesis enzyme JH acidO-methyltransferase (JHAMT). We also found the CA-projecting hugin neurons to likely express a gene encoding the specific receptor for diuretic hormone 44 (Dh44). Moreover, our data suggested that the CA-projecting hugin neurons have synaptic connections with the upstream neurons producing Dh44. To the best of our knowledge, this is the first study to identify a specific neurotransmitter of the CA-projecting neurons inD. melanogaster, and to anatomically characterize a neuronal pathway of the CA-projecting neurons and their upstream neurons.