J Pak Med Assoc. et al. When correcting the total body water deficit, oral or enteral free water should be used whenever possible. When the serum sodium is < 120 mEq/L (< 120 mmol/L), hyponatremia may not completely correct upon restoration of intravascular volume; restriction of free water ingestion to 500 to 1000 mL/24 hours may be needed. For example, the amount of sodium needed to raise the sodium level from 106 to 112 mEq/L in a 70-kg man can be calculated as follows: Because there is 513 mEq (mmol) sodium/L in hypertonic saline, roughly 0.5 L of hypertonic saline is needed to raise the sodium level from 106 to 112 mEq/L (mmol/L). Hew-Butler T, Calculated vs measured plasma osmolalities revisited. SIADH = syndrome of inappropriate antidiuretic hormone secretion. Leung AA, Clinicians should review the other drugs the patient is taking for potentially dangerous interactions with V2 receptor antagonists before initiating a treatment trial. Symptoms generally occur when the effective plasma osmolality falls to < 240 mOsm/kg (< 240 mmol/kg). N Engl J Med. 35. Severe symptoms are likely to occur with acute increases in plasma sodium levels or at concentrations greater than 160 mEq per L. Hypernatremia can cause brain shrinkage, resulting in vascular rupture and intracranial bleeding.33. 2000;342(20):1493–1499. Vasopressin (antidiuretic hormone [ADH]) secretion increases despite a decrease in osmolality to maintain blood volume. Symptoms of hypernatremia in infants can include tachypnea, muscle weakness, restlessness, a high-pitched cry, insomnia, lethargy, and coma. Tolvaptan, a selective oral vasopressin V2-receptor antagonist, for hyponatremia. Osmolality refers to the total concentration of solutes in water. 2010;21(4):705–712. When hypervolemic, fluid restriction, sometimes a diuretic, occasionally a vasopressin antagonist, In severe, rapid onset or highly symptomatic hyponatremia, partial rapid correction with hypertonic (3%) saline. The syndrome of inappropriate antidiuretic hormone and cerebral salt wasting are linked through a common cause—traumatic brain injury—and common result—hypotonic hyponatremia. With correction of the salt deficit, uric acid levels normalize in SIADH and not in cerebral salt wasting.3 The treatment of SIADH is fluid restriction (800–1000 ml/day) and occasional hypertonic saline. Measurement of serum osmolality is less than 280 mOsm/kg, and the urine osmolality is greater than 100 mOsm/kg in both diseases. The diagnostic workup should include a history and physical examination with specific attention to cardiac, cancer, pulmonary, surgical, endocrine, gastrointestinal, neurologic, and renal histories (Table 1).11–13 Diuretics, carbamazepine (Tegretol), and selective serotonin reuptake inhibitors can cause hypovolemia; therefore, medications should be reviewed. Inappropriately dilute urine (osmolality less than 300 mOsm per kg) in the setting of hypernatremia suggests diabetes insipidus. Vaptans appear to be safe for the treatment of severe hypervolemic and euvolemic hyponatremia but should not be used routinely. For patients with rapid-onset hyponatremia and neurologic symptoms, rapid correction is accomplished by giving 100 mL of hypertonic saline IV over 15 minutes. et al. Kahn A, J Nephrol. Hagino T, et al. It is not recommended in patients with advanced chronic kidney disease (estimated glomerular filtration rate < 30 mL/minute) and should not be used if anuria is present. Does preoperative hyponatremia potentiate the effects of left ventricular dysfunction on mortality after cardiac surgery? Accessed October 8, 2014. Hyponatremia: a problem-solving approach to clinical cases. Certain drugs (eg, cyclophosphamide, nonsteroidal anti-inflammatory drugs, chlorpropamide) potentiate the renal effect of endogenous vasopressin, whereas others (eg, oxytocin) have a direct vasopressin-like effect on the kidneys. In euvolemic (dilutional) hyponatremia, total body sodium and thus ECF volume are normal or near-normal; however, TBW is increased. Clinical findings suggestive of hypervolemic hyponatremia 2/2 decompensated cirrhosis resulting in decreased effective arterial blood volume and volume retention. This content is owned by the AAFP. Shchekochikhin DY, Josiassen RC, Common causes include diuretic use, diarrhea, heart failure, liver disease, and renal disease. 37. et al. The degree of hyponatremia, the duration and rate of onset , and the patient's symptoms are used to determine which treatment is most appropriate. Sodium disorders in the emergency department: a review of hyponatremia and hypernatremia, Lixivaptan is awaiting approval from the U.S. Food and Drug Administration for use in patients with euvolemia and hypervolemic hyponatremia, Estimated retail price based on information from, Information from: Dahl E, et al. Hyponatremia reflects an excess of total body water (TBW) relative to total body sodium content. Euvolemic patients should also have thyroid and adrenal function tested. Adam Peets, David Zygun, in Essentials of Neuroanesthesia and Neurointensive Care, 2008. Measurement of thyroid-stimulating hormone, urinary uric acid, adrenocorticotropic hormone, plasma cortisol, and brain natriuretic peptide may be considered in select patients to rule out other causes.13 The diagnosis of reset osmostat (a variation of syndrome of inappropriate antidiuretic hormone secretion [SIADH] in which ADH secretion occurs despite low plasma osmolality) may be aided using fractional excretion of urate (uric acid) in nonedematous patients who have hyponatremia that does not respond to usual treatment.17, Measured sodium + 0.024 × (serum glucose − 100)*, Measured sodium + 0.016 × (serum glucose − 100), Online calculators available at http://www.mdcalc.com/sodium-correction-for-hyperglycemia and http://www.medcalc.com/correctna.html, ([Plasma creatinine × urinary sodium] / [plasma sodium × urinary creatinine]) × 100, Prerenal < 1%, intrinsic > 1%, and postrenal > 4%, Online calculators available at http://www.mdcalc.com/fractional-excretion-of-sodium-fena and http://www.medcalc.com/fena.html, Online calculators for the rate of infusion and the concentration of sodium required are available at http://www.mdcalc.com/sodium-correction-rate-in-hyponatremia, http://www.medcalc.com/sodium.html, and http://www.nephromatic.com/sodium_correction.php, Serum sodium correction should generally not proceed faster than 0.5 mEq per L per hour for the first 24 to 48 hours; however, in severely symptomatic patients, the rate can be 1.0 to 2.0 mEq per L per hour; these situations typically require use of 3% saline, The goal is to raise the serum sodium level not to exceed 10 to 12 mEq per L in the first 24 hours and 18 mEq per L in the first 48 hours, Isotonic saline contains 154 mEq of sodium per L, and 3% saline contains 513 mEq of sodium per L, (Sodium × 2) + (glucose / 18) + (blood urea nitrogen / 2.8), In patients with hyperglycemia, uncorrected sodium should be used to calculate the osmolality, Online calculators available at http://www.mdcalc.com/serum-osmolality-osmolarity and http://www.medcalc.com/osmol.html, Total body water % × weight in kg × (desired sodium − actual sodium), For total body water %, use 0.6 for men and 0.5 for women, Example: for a 70-kg man with a serum sodium level of 120 mEq per L and a desired serum sodium level of 140 mEq per L, the calculation is 0.6 × 70 (140 − 120) = 42 × 20 = 840 mEq, Online calculator available at http://www.mdcalc.com/sodium-deficit-in-hyponatremia, Volume (L) = (total body water %) × weight in kg × [(sodium − 140) / 140], For total body water %, use 0.45 for women older than 65 years, 0.5 for women 65 years and younger and for men older than 65 years, and 0.6 for men 65 years and younger and for children, Example: for a 70-kg man with a serum sodium level of 120 mEq per L, the calculation is 0.6 × 70 × ([120 − 140] / 140) = 42 × (−20 / 140) = 42 × (−1 / 7) = −6 L, Online calculators available at http://www.mdcalc.com/free-water-deficit-in-hypernatremia and http://www.medcalc.com/freewater.html.