para>Increase Na levels slowly, no more than 10 mEq/L/24 hr, to prevent complications such as central pontine myelinolysis (CPM) (3)C.
ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
Patient Monitoring
- Careful continuous clinical and laboratory monitoring of hyponatremic state during acute phase:
- Hourly urine output
- Urine Na
- Serum Na and potassium (K) every 4 to 6 hours if moderate/severe, then daily once stable
- Goal sodium increase is <10 mEq/L in first 24-hour period, then 8 mEq/L in subsequent 24-hour periods until Na reaches 130 mEq/L (3)[C].
- Chronic management: Treat underlying cause; continue fluid restriction and NaCl tablets as needed.
DIET
Increase protein/solute intake and decrease water intake.
PATIENT EDUCATION
Diet and fluid restrictions
PROGNOSIS
- Depends on underlying cause; in general, higher morbidity and mortality in hospitalized patients with hyponatremia
- If symptomatic (seizure, coma): high mortality due to cerebral edema if serum Na <120 mEq/L (<120 mmol/L)
COMPLICATIONS
- Falls and hip fractures
- Cerebral edema (see "Prognosis " )
- Osmotic demyelination with overcorrection (see "Treatment " precautions): central pontine and extrapontine irreversible myelinolysis (6,11)
- Chronic hyponatremia
- Chronic hyponatremia is associated with osteoporosis (12)[C].
REFERENCES
11 Feldman BJ, Rosenthal SM, Vargas GA, et al. Nephrogenic syndrome of inappropriate antidiuresis. N Engl J Med. 2005;352(18):1884 " 1890.22 Tian W, Fu Y, Garcia-Elias A, et al. A loss of function non-synonymous polymorphism in the osmoregulatory TRPV4 gene is associated with human hyponatremia. Proc Natl Acad Sci U S A. 2009;106(33):14034 " 14039.33 Spasovski G, Vanholder R, Allolio B, et al. Clinical practice guideline on diagnosis and treatment of hyponatraemia. Nephrol Dial Transplant. 2014;29(Suppl 2):i1 " i39.44 Decaux G, Musch W. Clinical laboratory evaluation of the syndrome of inappropriate secretion of antidiuretic hormone. Clin J Am Soc Nephrol. 2008;3(4):1175 " 1184.55 Ellison DH, Berl T. Clinical practice. The syndrome of inappropriate antidiuresis. N Engl J Med. 2007;356(20):2064 " 2072.66 Adrogue HJ, Madias NE. The challenge of hyponatremia. J Am Soc Nephrol. 2012;23(7):1140 " 1148.77 Sterns RH, Nigwekar SU, Hix JK. The treatment of hyponatremia. Semin Nephrol. 2009;29(3):282 " 299.88 Esposito P, Piotti G, Bianzina S, et al. The syndrome of inappropriate antidiuresis: pathophysiology, clinical management and new therapeutic options. Nephron Clin Pract. 2011;119(1):c62 " c73.99 Friedman B, Cirulli J. Hyponatremia in critical care patients: frequency, outcome, characteristics, and treatment with the vasopressin V2-receptor antagonist tolvaptan. J Crit Care. 2013;28(2):219.e1 " e12.1010 Sherlock M, Thompson CJ. The syndrome of inappropriate antidiuretic hormone: current and future management options. Eur J Endocrinol. 2010;162(Suppl 1):S13 " S18.1111 Fleming JD, Babu S. Images in clinical medicine. Central pontine myelinolysis. N Engl J Med. 2008;359(23):e29.1212 Verbalis JG, Barsony J, Sugimura Y, et al. Hyponatremia-induced osteoporosis. J Bone Miner Res. 2010;25(3):554 " 563.
SEE ALSO
Hyponatremia
CODES
ICD10
E22.2 Syndrome of inappropriate secretion of antidiuretic hormone
ICD9
253.6 Other disorders of neurohypophysis
SNOMED
55004003 Syndrome of inappropriate vasopressin secretion (disorder)
CLINICAL PEARLS
- Treatment of the underlying cause is a key. Review all medications for potential culprits.
- Consultation is recommended in moderate to severe hyponatremia or if hypertonic saline indicated.
- Fluid restriction is the mainstay of treatment in SIADH. Fluid restriction fails to correct hyponatremia and Na wasting in salt-losing renal disease.
- Cerebral salt wasting is a controversial disease entity and is similar to SIADH. However, patients with SIADH are euvolemic, whereas patients with cerebral salt wasting are hypovolemic. The only real way to establish the diagnosis is through fluid restriction. Serum urate and fractional excretion of urate will be corrected with fluid restriction in SIADH, but will not correct in cerebral salt wasting.
- CPM is a cerebral demyelination syndrome that causes quadriplegia, pseudobulbar palsy, seizures, coma, and death. It is caused by an overly rapid rate of Na correction.
- Safe correction of hyponatremia is important. Online calculators are available: www.medcalc.com/sodium.html.