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Renal Disease; Fluid and Electrolyte Disorders
Published in John S. Axford, Chris A. O'Callaghan, Medicine for Finals and Beyond, 2023
As sodium is the major extracellular ion, it is the major determinant of body water content. Generally, the body will maintain osmolality, even at the expense of volume changes. This makes sense because a small change in body water content is tolerated by changes in vessel tone, but a change in the osmotic gradient across cell membranes has severe effects on cells, such as causing seizures in the brain. Control of osmolality: Osmoreceptors in the hypothalamus detect changes in osmolality and trigger changes in water intake by thirst and in water excretion by altering vasopressin (ADH) secretion. This maintains osmolality by changing water handling but does not control body osmolyte content.Control of volume: Volume receptors in the circulation detect stretch. Sodium handling by the kidney is influenced especially by angiotensin II and aldosterone. Because osmolality will normally be maintained, the total body water volume is controlled by changing the amount of sodium in the body. For example, if body volume is low, the kidney retains sodium, which increases plasma osmolality. The osmolality regulating system then causes more water to be drunk and less to be excreted by the kidney and the result is an increase in total body water.
The Endocrine System and Its Disorders
Published in Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss, Understanding Medical Terms, 2020
Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss
A condition called diabetes insipidus results from hyposecretion of vasopressin by the pituitary gland. The disorder in which there is continual release of ADH unrelated to plasma osmolality is known as the syndrome of inappropriate diuretic hormone (SIADH). This occurs in association with several clinical disorders, particularly malignant tumors such as oat-cell carcinoma of the lung. Symptoms include weight gain, weakness, lethargy, mental confusion, and progression to convulsions and coma.
Erythrocyte Deformability
Published in Gordon D. O. Lowe, Clinical Blood Rheology, 2019
A more generalized increase in plasma osmolality occurs in diabetes mellitus,44 renal failure,45 and alcoholism.46 Also, in a study of 14 marathon runners, a significant correlation (r = 0.59 to 0.69) was found between filtration of whole blood through 5 µm diameter pores and increase in plasma osmolality.47 Since glucose rapidly equilibrates across the erythrocyte membrane (half-time of efflux ∼25 sec),48 and urea possibly faster,16 osmotic equilibrium between erythrocyte cytoplasm and plasma should theoreticaly occur. In diabetes, however, the increase in erythrocyte glucose concentration is likely to stimulate the polyol pathway and cause intracellular accumulation of sorbitol, which could prolong the osmotic differential effect.49,50 These in vivo osmotic effects should therefore be considered in the design and interpretation of rheological studies and care should be taken to maintain any hyperosmolar stress during in vitro rheological testing since reversal of the osmotic imbalance may otherwise occur.
Is a hyperosmolar pump prime for cardiopulmonary bypass a risk factor for postoperative delirium? A double blinded randomised controlled trial
Published in Scandinavian Cardiovascular Journal, 2023
Helena Claesson Lingehall, Yngve Gustafson, Staffan Svenmarker, Micael Appelblad, Fredrik Davidsson, Fredrik Holmner, Alexander Wahba, Birgitta Olofsson
The risk for POD increases by 9% in the study group (OR 1.09, 95% CI 1.03–1.15) on day 1 and by 10% (OR 1.10, 95% CI 1.04–1.16) on day 3 postoperatively. Patients diagnosed with POD had higher plasma osmolality levels, both on days 1 and 3 after surgery. The plasma osmolality increased to 323 (14) mOsmol/kg in the study group vs. 295 (5) mOsmol/kg (p < .001) in the control group at the start of CPB. These differences persisted at weaning: 309 (8) mOsmol/kg vs. 297 (5) mOsmol/kg (p < .001) and on day 1 postoperatively: 294 (9) mOsmol/kg vs. 288 (7) mOsmol/kg (p < .001). Plasma osmolality returned to normal on day 3: 290 (7) mOsmol/kg. All patients in the study group had plasma osmolality levels above 295 mOsmol/kg during CPB. Of note, this was also detected among 63% of the control patients at weaning from bypass. Refer to Figure 2 for a summary.
Renal and Hepatic Disease: Cnidoscolus aconitifolius as Diet Therapy Proposal for Prevention and Treatment
Published in Journal of the American College of Nutrition, 2021
Maria Lilibeth Manzanilla Valdez, Maira Rubi Segura Campos
Another important function of the kidneys is the regulation of the hydro-electrolytic balance, this is done by the excretion of water and electrolytes such as ions like chlorine (Cl−), potassium (K+), calcium (Ca+2), hydrogen (H+), magnesium (Mg+2), and phosphorus (PO4−3). The purpose of this system in the kidney is to maintain homeostasis in the body and to regulate the intake of water in the body. The regulation of water intake is related to plasma osmolality; the hypothalamus detects the changes of osmolality, which activates the sensation of thirst and the secretion of the antidiuretic hormone (ADH). In CKD, the reabsorption of sodium (Na+) increases, consequently the extracellular volume changes and urinary excretion diminishes, which results in edema (18). Edema is very common in CKD; therefore, it is necessary to have an accurate control of fluid intake. The WHO determined that the recommended daily intake (RDI) of Na+ for the adult population is 1600 mg per day. For its part, the study conducted in 2009 by the Mexican Institute of Medical Science and Nutrition Salvador Zubirán, estimated that the daily consumption of salt in Mexico is 9 g in men and 7 g in women, noticing that Mexicans have a high consumption of sodium, and how dangerous a diet with this characteristics is. Diets with a high Na+ content stimulate electrolyte imbalance in CKD (3).
Mechanisms involved in the cardiovascular effects caused by acute osmotic stimulation in conscious rats
Published in Stress, 2020
Eduardo Albino Trindade Fortaleza, Cristiane Busnardo, Aline Fassini, Ivaldo Jesus Almeida Belém-Filho, Gislaine Almeida-Pereira, José Antunes-Rodrigues, Fernando Morgan Aguiar Corrêa
Changes in plasma osmolality are identified by central and peripheral osmoreceptors (Antunes-Rodrigues, de Castro, Elias, Valenca, & McCann, 2004; Bourque, Oliet, & Richard, 1994; Haberich, 1968). Increases in plasma concentration of NaCl, the main determinant of plasma osmolality and extracellular fluid volume, induce behavioral and neurovegetative adjustments, such as a blood pressure (BP) increase, associated with neurohumoral changes, including sympathetic nervous system activation and vasopressin release (Akins & Bealer, 1990; Antunes-Rodrigues et al., 2004; Crofton & Share, 1989; Garcia-Estan, Carbonell, Garcia-Salom, Salazar, & Quesada, 1989; Onaka & Yagi, 2001; Sharp, Sagar, Hicks, Lowenstein, & Hisanaga, 1991; Weiss, Claassen, Hirai, & Kenney, 1996; Xiong & Hatton, 1996).