tailieunhanh - Hyponatremia

Tham khảo tài liệu 'hyponatremia', y tế - sức khoẻ, y dược phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Hyponatremia Definition Hyponatremia is defined as a plama Na 135 mEq L. Etiology Any process that limits the elimination of water or expands the volume around a fixed Na content may lead to a decrease in Na concentration. -Expansion of the space surrounding the Na content Pseudohyponatremia a high content of plasma proteins and lipids expands the nonaqueous portion of the plasma sample leading to an errant report of a low ECF Na . Hyperosmolar hyponatremia an osmotically active solute other than Na accumulates in the ECF drawing water into the ECF and diluting the Na content. Common causes hyperglycemia resulting in a fall in plasma Na of to mEq L for every 100 mg dL rise in plasma glucose post-transurethral resection of the prostate post-TURP syndrome glycine mannitol or sorbitol can be absorbed into the ECF during bladder irrigation Rarely the ECF water content rises simply because the ingested quantity of water exceeds the physiologic capacity of water excretion in the kidney as in psychogenic polydipsia water intoxication from poorly conceived drinking games beer potomania and the so-called tea and toast diet. - Appropriate ADH secretion occurs with a fall in effective circulating volume. In these conditions thirst and water retention is stimulated protecting volume status at the cost of the osmolar status. This category is classically subdivided based on the associated assessment of ECF status. Hypovolemic hyponatremia may result from any causes of net Na loss. Hypervolemic hyponatremia occurs in edematous states such as congestive heart failure CHF hepatic cirrhosis and severe nephrotic syndrome. Despite the expanded interstitial space the circulating volume is reduced. Alterations in Starling forces contribute to this apparent paradox shifting fluid from the intravascular to interstitial space. - Inappropriate secretion of ADH is characterized by the activation of waterconserving mechanisms despite the absence of osmotic or volume-related stimuli. .