Water and Electrolytes II PDF

Objectives Explain the basic concepts of water and salt loss Water and electrolytes II Explain potassium disturbances Dr Xikombiso Nkuna...

Objectives Explain the basic concepts of water and salt loss Water and electrolytes II Explain potassium disturbances Dr Xikombiso Nkuna Understand electrolytes imbalance conditions such as: Chemical Pathology Department Hypernatremia Hyponatremia Hyperkalemia Hypokalemia Understand the clinical effects and management of electrolytes in the body fluids. Sodium balance Renal handling of sodium The volume of the extracellular fluid (ECF) is directly dependent on the total body Na+ content. Sodium is mainly confined to the ECF. Water intake and loss are regulated to maintain a constant ECF osmolality and sodium concentration. Sodium balance is maintained by regulation of its excretion by the kidneys. Hyponatraemia Hyponatraemia Hyponatremia is defined as a decreased plasma sodium concen tration (30 mmol/L) No clinical evidence of volume depletion or oedema SIADH management Hypernatraemia Restrict water intake Hypernatremia (defined as plasma Na>145 mmol/L) is always hyperosmolar and is less common than hyponatremia. Hypertonic saline risk of fluid overload→ pulmonary oedema Hypernatremia occurs frequently in critically ill patients, where patients may be unable to drink water. In chronic dilutional hyponatraemia: correct the sodium slowly to avoid causing central pontine myelinolysis Symptoms of hypernatremia are primarily neurologic (because of neuronal cell loss of H2O to the ECF) including tremors, irritability, Treat the underlying cause ataxia, confusion and coma. Hypernatraemia Diabetes insipidus DI is characterized by dilute urine (osmolality