Hyponatremia physiology

Carbamoyl phosphate synthetase 1 (CPS1) is the most abundant hepatocyte mitochondrial matrix protein. Hypoosmotic stress increases CPS1 release in isolated mouse hepatocytes without cell death. We hypothesized that increased CPS1 release during hypoosmosis is selective and associates with altered mitochondrial morphology. Both ex vivo and in vivo models were assessed. Mouse hepatocytes and livers were challenged with isotonic or hypoosmotic (35 mOsm) buffer. Mice were injected intraperitoneally with water (10% body weight) with or without an antidiuretic...

Electrolyte disorders are very common in the pediatric population. Derangements in serum sodium and potassium concentrations are among the most frequently seen given the risk factors and comorbidities unique to children. Pediatricians, in both outpatient and inpatient settings, should be comfortable with the evaluation and initial treatment of disturbances in these electrolyte concentrations. However, to evaluate and treat a child with abnormal serum concentrations of sodium or potassium, it is critical to understand the regulatory physiology that governs osmotic homeostasis and potassium regulation in the body...

Hyponatremia is common among children undergoing treatment for hematologic malignancies and may be attributed to multiple underlying causes. In cases of hyponatremia due to mixed physiology, the osmolal gap, can identify pseudohyponatremia that may be masked by other causes.

Based on a comprehensive review and critical analysis of the literature regarding the nutritional concerns of female athletes, conducted by experts in the field and selected members of the International Society of Sports Nutrition (ISSN), the following conclusions represent the official Position of the Society: 1. Female athletes have unique and unpredictable hormone profiles, which influence their physiology and nutritional needs across their lifespan. To understand how perturbations in these hormones affect the individual, we recommend that female athletes of reproductive age should track their hormonal status (natural, hormone driven) against training and recovery to determine their individual patterns and needs and peri and post-menopausal athletes should track against training and recovery metrics to determine the individuals' unique patterns...

OBJECTIVES: To assess the effect of isotonic normal saline (NS) versus water post-Ryles Tube (RT) feeding upon hyponatremia and blood parameters in Intensive Care Units (ICU) admitted patients. METHODS: A parallel group randomized controlled trial design. The total sample size taken for this pilot trial was N = 50 as a thumb rule (n = 25 in each arm) selected by using a simple random sampling method. The sample was ICU-admitted patients with mild and moderate hyponatremia...

Late-onset hyponatremia (LOH) frequently affects premature infants 2 or more weeks of age due to inadequate sodium intake and excessive kidney loss. Late-onset hyponatremia typically occurs in infants who are physiologically stable and is defined as serum sodium of 132 mEq/L or less or between 133 and 135 mEq/L if receiving sodium supplementation. Recent evidence suggests that spot urine sodium levels may improve the recognition of LOH, as low levels of excreted urine reflect a total body sodium deficit and negative balance...

The purpose of perioperative fluid management in children is to maintain adequate volume status, electrolyte level, and endocrine system homeostasis during the perioperative period. Although hypotonic solutions containing glucose have traditionally been used as pediatric maintenance fluids, recent studies have shown that isotonic balanced crystalloid solutions lower the risk of hyponatremia and metabolic acidosis perioperatively. Isotonic balanced solutions have been found to exhibit safer and more physiologically appropriate characteristics for perioperative fluid maintenance and replacement...

Multisystem inflammatory syndrome is associated with COVID-19 and can result in reduced food intake, increased muscle catabolism, and electrolyte imbalance. Therefore COVID-19 patients are at high risk of being malnourished and of refeeding syndrome. The present study aimed to determine the prevalence and correlates of malnutrition and refeeding syndrome (RS) among COVID-19 patients in Hanoi, Vietnam. This prospective cohort study analyzed data from 1207 patients who were treated at the COVID-19 hospital of Hanoi Medical University (HMUH COVID-19) between September 2021 and March 2022...

Study Objective: To understand the response of mice lacking the insulin-regulated aminopeptidase (IRAP) to an acute water load. Hypothesis: For mammals to respond appropriately to acute water loading, vasopressin activity needs to decrease. IRAP degrades vasopressin in vivo. Therefore, we hypothesized that mice lacking IRAP have impaired ability to degrade vasopressin and thus have persistent urinary concentration. Methods: Age matched 8 to 12-week-old IRAP wild-type WT and KO male mice were used for all experiments...

Hyponatremia is one of the most common problems encountered in clinical practice and one of the least-understood because accurate diagnosis and management require some familiarity with water homeostasis physiology, making the topic seemingly complex. The prevalence of hyponatremia depends on the nature of the population studied and the criteria used to define it. Hyponatremia is associated with poor outcomes including increased mortality and morbidity. The pathogenesis of hypotonic hyponatremia involves the accumulation of electrolyte-free water caused by either increased intake and/or decrease in kidney excretion...

Cisplatin is a well-known chemotherapeutic agent that can be associated with hyponatremia. It is known to be associated with a multitude of renal disorders including acute kidney injury with reduced glomerular filtration, Fanconi syndrome, and renal tubular acidosis, nephrogenic diabetes insipidus and renal salt wasting syndrome. We report a case of an elderly male presenting with significant recurrent hyponatremia, and prerenal azotemia. With recent exposure to cisplatin along with significant hypovolemia and urinary loss of sodium, he was diagnosed to have cisplatin induced renal salt wasting syndrome...

Nephrogenic Syndrome of Inappropriate Antidiuresis (NSIAD) is a rare X-linked disease caused by gain-of-function mutations of the V2 vasopressin receptor (V2R). NSIAD patients are characterized by the inability to excrete a free water load and inappropriately increased urinary osmolality despite very low levels of plasma vasopressin resulting in euvolemic hyponatremia. To dissect the signaling downstream V2R constitutively active variants, Flp-In T-REx Madin-Darby canine kidney (FTM) cells, stably transfected with V2R mutants (R137L, R137C, and F229V) and AQP2-wt or non-phosphorylatable AQP2-S269A/AQP2-S256A, were used as cellular models...

BACKGROUND: Hospital-acquired hyponatremia remains a feared event in patients receiving hypotonic fluid therapy. Our objectives were to assess post-operative plasma-sodium concentration and to provide a physiological explanation for plasma-sodium levels over time in children with acute appendicitis. METHODS: Thirteen normonatremic (plasma-sodium ≥135 mmol/L) children (8 males), median age 12.3 (IQR 11.5-13.5) years participated in this prospective observational study (ACTRN12621000587808)...

OBJECTIVE: There is no consistent opinion on the optimal initial dose of desmopressin for patients with nocturnal polyuria. Over a period of 12 weeks, we investigated the safety and efficacy of an initial dose of 50 μg of desmopressin for elderly men. METHODS: Eighty patients (mean age: 78.8 years) were started on an initial dose of 50 μg of desmopressin for nocturia associated with nocturnal polyuria. Safety and efficacy were evaluated after 1, 4, and 12 weeks using a frequency-volume chart, Athens Insomnia Scale, Patient Global Impression of Improvement scale, physical examination, blood tests, and a body composition analyzer...

In cirrhosis, several molecular alterations such as resistance to apoptosis could accelerate carcinogenesis. Recently, mechanotransduction has been attracting attention as one of the causes of these disturbances. In patients with cirrhosis, the serum sodium levels progressively decrease in the later stage of cirrhosis, and hyponatremia leads to serum hypo-osmolality. Since serum sodium levels in patients with cirrhosis with liver cancer are inversely related to cancer's number, size, stage, and cumulative survival, we hypothesized that hypo-osmolality-induced mechanotransduction under cirrhotic conditions might contribute to oncogenesis and/or progression of hepatocellular carcinoma (HCC)...

Thyroid hormones have various effects on the body which include electrolyte and water hemostasis. It is also involved in renal development and physiology. Hyponatremia is a serious electrolyte imbalance that can be associated with the involvement of different body systems and a wide range of deleterious changes. We report a case of a 62-years-old female with the symptoms of severe hyponatremia like altered mental sensorium with a serum sodium level of 110 meq/l. After ruling out other causes, a final diagnosis of hypothyroidism was made...

Body sodium (Na) levels must be maintained within a narrow range for the correct functioning of the organism (Na homeostasis). Na disorders include not only elevated levels of this solute (hypernatremia), as in diabetes insipidus, but also reduced levels (hyponatremia), as in cerebral salt wasting syndrome. The balance in body Na levels therefore requires a delicate equilibrium to be maintained between the ingestion and excretion of Na. Salt (NaCl) intake is processed by receptors in the tongue and digestive system, which transmit the information to the nucleus of the solitary tract via a neural pathway (chorda tympani/vagus nerves) and to circumventricular organs, including the subfornical organ and area postrema, via a humoral pathway (blood/cerebrospinal fluid)...

BACKGROUND: Hyponatremia associated with a low serum osmolality is a common and confounding electrolyte disorder. Correcting hyponatremia is also complicated, especially in the setting of chronic hyponatremia. Here, we provide a rational approach to accurately detecting and safely treating acute on chronic euvolemic hyponatremia in the setting of acute polydipsia with a chronic reset osmostat. CASE PRESENTATION: A 71-year-old hispanic gentleman with chronic hyponatremia presented with hiccups, polydipsia, and a serum sodium concentration of 120 mEq/L associated with diffuse weakness, inattentiveness, and suicidal ideation...

Treating chronic hyponatremia by continuous renal replacement therapy (CRRT) is challenging because the gradient between a replacement fluid's [sodium] and a patient's serum sodium can be steep, risking too rapid of a correction rate with possible consequences. Besides CRRT, other gains and losses of sodium- and potassium-containing solutions, like intravenous fluid and urine output, affect the correction of serum sodium over time, known as osmotherapy. The way these fluids interact and contribute to the sodium/potassium/water balance can be parsed as a mixing problem...

A hyponatremic patient with the syndrome of inappropriate antidiuresis (SIAD) gets normal saline (NS), and the plasma sodium decreases, paradoxically. To explain, desalination is often invoked: if urine is more concentrated than NS, the fluid's salts are excreted while some water is reabsorbed, exacerbating hyponatremia. But comparing concentrations can be deceiving. They should be converted to quantities because mass balance is key to unlocking the paradox. The [sodium] equation can legitimately be used to track all of the sodium, potassium, and water entering and leaving the body...