If volume loss is due to vomiting, a low urine chloride concentration is corroborative. Treatment is intravenous (IV) normal saline as well as managing the condition that precipitated the volume loss.Cognitive learning theory in the classroom hypertonic saline is reserved for symptomatic hyponatremia. As volume is restored, the stimulus for ADH release will decrease, potentially leading to correction of the serum sodium concentration too quickly; consequently, serum sodium levels must be monitored closely.Cognitive learning theory in the classroom correcting hyponatremia too rapidly can lead to osmotic demyelination syndrome (previously known as central pontine myelinolysis), which is characterized by flaccid paralysis, dysarthria, and dysphagia.Cognitive learning theory in the classroom the rate of sodium correction must be 0.3 to 0.5 meq/L/h or less (0.3–0.5 mmol/L/h).

Hypo-osmolal hyponatremia with euvolemia is caused by either massive intake of water or an inability of the kidney to excrete a free water load.Cognitive learning theory in the classroom the normal renal capacity for water excretion is approximately 15 L/day. A massive increase in water intake occurs in psychogenic polydipsia or, rarely, in hypothalamic diseases.Cognitive learning theory in the classroom urine indices are compatible with adequate intravascular volume (urine sodium concentration >20 meq/L [20 mmol/L]), and the urine is maximally dilute (50-100 mosm/kg [mmol/kg]).Cognitive learning theory in the classroom treatment is water restriction.

Hypothyroidism, adrenal insufficiency, reset osmostat, inadequate osmoles, and syndrome of inappropriate ADH secretion (SIADH) all are associated with hyponatremia caused by a renal defect in excreting free water.Cognitive learning theory in the classroom thyroid and cortisol deficiencies lead to increased ADH release. The most common physiologic stimulus for reset osmostat is pregnancy, which contributes to the increase in plasma volume.Cognitive learning theory in the classroom at least 50 mosm (50 mmol) is needed to excrete 1 L of water via the urinary tract; malnourished patients may not have adequate osmoles to excrete excess free water.Cognitive learning theory in the classroom treatment is water restriction until nutrition can be corrected. SIADH always is associated with hyponatremia but is a diagnosis of exclusion.Cognitive learning theory in the classroom urine indices are compatible with euvolemia (urine sodium concentration >20 meq/L [20 mmol/L]), but the urine is inappropriately concentrated in the face of plasma hypo-osmolality.Cognitive learning theory in the classroom SIADH often is accompanied by very low serum uric acid and blood urea nitrogen levels, which help differentiate it from other causes of hyponatremia.Cognitive learning theory in the classroom causes of SIADH include malignancy (eg, small cell carcinoma of the lung); medications; intracranial pathology; and pulmonary diseases, especially disorders that increase intrathoracic pressure and decrease venous return to the heart.Cognitive learning theory in the classroom

Symptoms occur at a serum sodium level of 110 meq/L (110 mmol/L) and include obtundation, coma, seizures, and death (if untreated). In general, symptoms tend to be worse when the hyponatremia develops quickly.Cognitive learning theory in the classroom serum sodium level should be corrected to 120 meq/L (120 mmol/L) at a rate of 1 to 2 meq/L/h (1-2 mmol/L/h); when this level is achieved, the rate of correction is slowed to 0.3 to 0.5 meq/L/h (0.3–0.5 mmol/L).Cognitive learning theory in the classroom the quantity of sodium chloride required to increase the serum sodium concentration is calculated as:

Hypertonic saline should be used with caution and only for patients with symptomatic severe hyponatremia.Cognitive learning theory in the classroom the IV vasopressin receptor antagonist conivaptan and the oral vasopressin receptor antagonist tolvaptan are approved for the treatment of euvolemic and hypervolemic hyponatremia.Cognitive learning theory in the classroom these agents should not be used to treat hypovolemic hyponatremia. As with the administration of saline, care must be taken to prevent overly rapid correction of the serum sodium concentration.Cognitive learning theory in the classroom the efficacy of tolvaptan may be limited by stimulated thirst.