Hyponatremia Workup

  • Author: Eric E Simon, MD; Chief Editor: Vecihi Batuman, MD, FACP, FASN   more...
 
Updated: Mar 6, 2012
 

Laboratory Studies

There are 3 essential laboratory tests in the evaluation of patients with hyponatremia that, together with the history and the physical examination, help to establish the primary underlying etiologic mechanism. (In general, the etiology of the hyponatremia directs its management.) These tests are as follows:

  • Urine osmolality helps to differentiate between conditions associated with impaired free water excretion and primary polydipsia, in which water excretion should be normal (provided intact kidney function). With primary polydipsia, as with malnutrition (severe decreased solids intake) and reset osmostat, the urine osmolality is maximally dilute, generally less than 100 mOsm/kg. A urine osmolality greater than 100 mOsm/kg indicates impaired ability of the kidneys to dilute the urine. This usually is secondary to elevated vasopressin (ADH) levels, appropriate or inappropriate.
  • Serum osmolality readily differentiates between true hyponatremia and pseudohyponatremia secondary to hyperlipidemia, hyperproteinemia, or hypertonic hyponatremia associated with elevated glucose, mannitol, glycine (posturologic or postgynecologic procedure), sucrose, or maltose (contained in IgG formulations).
  • Urinary sodium concentration helps to differentiate between hyponatremia secondary to hypovolemia and SIADH. With SIADH (and salt-wasting syndrome), the urine sodium is greater than 20-40 mEq/L. With hypovolemia, the urine sodium typically measures less than 25 mEq/L. However, if sodium intake in a patient with SIADH (or salt-wasting) happens to be low, then urine sodium may fall below 25 mEq/L.

Ancillary tests

Serum uric acid levels: Can be important supportive information (typically reduced in SIADH and also reduced in salt wasting). After correction of hyponatremia, the hypouricemia corrects in SIADH but remains with a salt-wasting process.

Thyroid-stimulating hormone (TSH) and serum cortisol levels: If hypothyroidism or hypoadrenalism is suspected.

Serum albumin, triglycerides, and a serum protein electrophoresis: Also may be indicated for particular patients.

Next

Imaging Studies

Head computed tomography (CT) scanning and chest radiography can be used to assess for an underlying etiology in select patients with suspected SIADH or cerebral salt wasting.

Previous
Proceed to Treatment & Management
 
 
Contributor Information and Disclosures
Author

Eric E Simon, MD  Professor of Medicine, Chief, Section of Nephrology and Hypertension, Tulane University School of Medicine; Director, Nephrology Training, Medical Director, Dialysis Clinic, Inc, Canal Street

Eric E Simon, MD is a member of the following medical societies: American Federation for Medical Research, American Heart Association, American Society for Cell Biology, American Society of Nephrology, Association for Psychological Science, Central Society for Clinical Research, International Society of Nephrology, National Kidney Foundation, Phi Beta Kappa, and Southern Society for Clinical Investigation

Disclosure: Nothing to disclose.

Coauthor(s)

Seyed Mehrdad Hamrahian, MD  Assistant Professor of Medicine

Seyed Mehrdad Hamrahian, MD is a member of the following medical societies: American Society of Nephrology and National Kidney Foundation

Disclosure: Nothing to disclose.

Federico J Teran, MD  Instructor of Clinical Medicine, Section of Nephrology and Hypertension, Tulane University School of Medicine

Federico J Teran, MD is a member of the following medical societies: American College of Physicians, American Medical Association, American Society of Nephrology, Louisiana State Medical Society, National Kidney Foundation, and Renal Physicians Association

Disclosure: Nothing to disclose.

Specialty Editor Board

James H Sondheimer, MD, FACP  Associate Professor of Medicine, Wayne State University School of Medicine; Medical Director of Hemodialysis, Harper University Hospital at Detroit Medical Center; Medical Director, DaVita Greenview Dialysis (Southfield)

James H Sondheimer, MD, FACP is a member of the following medical societies: American College of Physicians and American Society of Nephrology

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD  Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

Eleanor Lederer, MD  Professor of Medicine, Chief, Nephrology Division, Director, Nephrology Training Program, Director, Metabolic Stone Clinic, Kidney Disease Program, University of Louisville School of Medicine; Consulting Staff, Louisville Veterans Affairs Hospital

Eleanor Lederer, MD is a member of the following medical societies: American Association for the Advancement of Science, American Federation for Medical Research, American Society for Biochemistry and Molecular Biology, American Society for Bone and Mineral Research, American Society of Nephrology, American Society of Transplantation, International Society of Nephrology, Kentucky Medical Association, National Kidney Foundation, and Phi Beta Kappa

Disclosure: Dept of Veterans Affairs Grant/research funds Research

Rebecca J Schmidt, DO, FACP, FASN  Professor of Medicine, Section Chief, Department of Medicine, Section of Nephrology, West Virginia University School of Medicine

Rebecca J Schmidt, DO, FACP, FASN is a member of the following medical societies: American College of Physicians, American Medical Association, American Society of Nephrology, International Society of Nephrology, National Kidney Foundation, Renal Physicians Association, and West Virginia State Medical Association

Disclosure: Renal Ventures Ownership interest Other

Chief Editor

Vecihi Batuman, MD, FACP, FASN  Professor of Medicine, Section of Nephrology-Hypertension, Tulane University School of Medicine; Chief, Medicine Service, Southeast Louisiana Veterans Health Care System

Vecihi Batuman, MD, FACP, FASN is a member of the following medical societies: American College of Physicians, American Society of Hypertension, American Society of Nephrology, and International Society of Nephrology

Disclosure: Nothing to disclose.

References

  1. Zenenberg RD, Carluccio AL, Merlin MA. Hyponatremia: evaluation and management. Hosp Pract (Minneap). Feb 2010;38(1):89-96. [Medline].

  2. Zeidel ML. Hyponatremia: mechanisms and newer treatments. Endocr Pract. Sep-Oct 2010;16(5):882-7. [Medline].

  3. Singhi S, Jayashre M. Free water excess is not the main cause for hyponatremia in critically ill children receiving conventional maintenance fluids. Indian Pediatr. Jul 2009;46(7):577-83. [Medline].

  4. Gross P, Reimann D, Henschkowski J, Damian M. Treatment of severe hyponatremia: conventional and novel aspects. J Am Soc Nephrol. Feb 2001;12 Suppl 17:S10-4. [Medline].

  5. Dubois GD, Arieff AI. Treatment of hyponatremia: the case for rapid correction. In: Narins RG, ed. Controversies in Nephrology and Hypertension. New York: Churchill Livingstone Inc; 1984:393-407.

  6. Goldberg A, Hammerman H, Petcherski S, et al. Prognostic importance of hyponatremia in acute ST-elevation myocardial infarction. Am J Med. Aug 15 2004;117(4):242-8. [Medline].

  7. Heuman DM, Abou-Assi SG, Habib A, Williams LM, Stravitz RT, Sanyal AJ. Persistent ascites and low serum sodium identify patients with cirrhosis and low MELD scores who are at high risk for early death. Hepatology. Oct 2004;40(4):802-10. [Medline].

  8. Kim MY, Baik SK, Yea CJ, et al. Hepatic venous pressure gradient can predict the development of hepatocellular carcinoma and hyponatremia in decompensated alcoholic cirrhosis. Eur J Gastroenterol Hepatol. Nov 2009;21(11):1241-6. [Medline].

  9. Bettari L, Fiuzat M, Shaw LK, Wojdyla DM, Metra M, Felker GM, et al. Hyponatremia and long-term outcomes in chronic heart failure-an observational study from the duke databank for cardiovascular diseases. J Card Fail. Jan 2012;18(1):74-81. [Medline].

  10. Hillier TA, Abbott RD, Barrett EJ. Hyponatremia: evaluating the correction factor for hyperglycemia. Am J Med. Apr 1999;106(4):399-403. [Medline].

  11. Issa MM, Young MR, Bullock AR, Bouet R, Petros JA. Dilutional hyponatremia of TURP syndrome: a historical event in the 21st century. Urology. Aug 2004;64(2):298-301. [Medline].

  12. Palmer BF. Hyponatraemia in a neurosurgical patient: syndrome of inappropriate antidiuretic hormone secretion versus cerebral salt wasting. Nephrol Dial Transplant. Feb 2000;15(2):262-8. [Medline].

  13. Palmer BF. Hyponatremia in patients with central nervous system disease: SIADH versus CSW. Trends Endocrinol Metab. May-Jun 2003;14(4):182-7. [Medline].

  14. Smith D, Moore K, Tormey W, Baylis PH, Thompson CJ. Downward resetting of the osmotic threshold for thirst in patients with SIADH. Am J Physiol Endocrinol Metab. Nov 2004;287(5):E1019-23. [Medline].

  15. Skippen P, Adderley R, Bennett M, et al. Iatrogenic hyponatremia in hospitalized children: Can it be avoided?. Paediatr Child Health. Jul 2008;13(6):502-6. [Medline]. [Full Text].

  16. Thaler SM, Teitelbaum I, Berl T. "Beer potomania" in non-beer drinkers: effect of low dietary solute intake. Am J Kidney Dis. Jun 1998;31(6):1028-31. [Medline].

  17. Goldman MB, Luchins DJ, Robertson GL. Mechanisms of altered water metabolism in psychotic patients with polydipsia and hyponatremia. N Engl J Med. Feb 18 1988;318(7):397-403. [Medline].

  18. Kratz A, Siegel AJ, Verbalis JG, et al. Sodium status of collapsed marathon runners. Arch Pathol Lab Med. Feb 2005;129(2):227-30. [Medline].

  19. Almond CS, Shin AY, Fortescue EB, et al. Hyponatremia among runners in the Boston Marathon. N Engl J Med. Apr 14 2005;352(15):1550-6. [Medline].

  20. Hew-Butler T, Almond C, Ayus JC, et al. Consensus statement of the 1st International Exercise-Associated Hyponatremia Consensus Development Conference, Cape Town, South Africa 2005. Clin J Sport Med. Jul 2005;15(4):208-13. [Medline].

  21. Baker J, Cotter JD, Gerrard DF, Bell ML, Walker RJ. Effects of indomethacin and celecoxib on renal function in athletes. Med Sci Sports Exerc. May 2005;37(5):712-7. [Medline].

  22. Feldman BJ, Rosenthal SM, Vargas GA, et al. Nephrogenic syndrome of inappropriate antidiuresis. N Engl J Med. May 5 2005;352(18):1884-90. [Medline].

  23. Trivelli A, Ghiggeri GM, Canepa A, Oddone M, Bava G, Perfumo F. Hyponatremic-hypertensive syndrome with extensive and reversible renal defects. Pediatr Nephrol. Jan 2005;20(1):102-4. [Medline].

  24. Sherlock M, O'Sullivan E, Agha A, et al. Incidence and pathophysiology of severe hyponatraemia in neurosurgical patients. Postgrad Med J. Apr 2009;85(1002):171-5. [Medline].

  25. Adrogue HJ, Madias NE. Hyponatremia. N Engl J Med. May 25 2000;342(21):1581-9. [Medline].

  26. Vachharajani TJ, Zaman F, Abreo KD. Hyponatremia in critically ill patients. J Intensive Care Med. Jan-Feb 2003;18(1):3-8. [Medline].

  27. Dixon MB, Lien YH. Tolvaptan and its potential in the treatment of hyponatremia. Ther Clin Risk Manag. Dec 2008;4(6):1149-55. [Medline]. [Full Text].

  28. Farmakis D, Filippatos G, Kremastinos DT, Gheorghiade M. Vasopressin and vasopressin antagonists in heart failure and hyponatremia. Curr Heart Fail Rep. Jun 2008;5(2):91-6. [Medline].

  29. Ayus JC, Wheeler JM, Arieff AI. Postoperative hyponatremic encephalopathy in menstruant women. Ann Intern Med. Dec 1 1992;117(11):891-7. [Medline].

  30. Ruzek KA, Campeau NG, Miller GM. Early diagnosis of central pontine myelinolysis with diffusion-weighted imaging. AJNR Am J Neuroradiol. Feb 2004;25(2):210-3. [Medline].

  31. Yu J, Zheng SS, Liang TB, Shen Y, Wang WL, Ke QH. Possible causes of central pontine myelinolysis after liver transplantation. World J Gastroenterol. Sep 1 2004;10(17):2540-3. [Medline].

  32. Doshi SM, Shah P, Lei X, Lahoti A, Salahudeen AK. Hyponatremia in hospitalized cancer patients and its impact on clinical outcomes. Am J Kidney Dis. Feb 2012;59(2):222-8. [Medline].

  33. Budisavljevic MN, Stewart L, Sahn SA, Ploth DW. Hyponatremia associated with 3,4-methylenedioxymethylamphetamine ("Ecstasy") abuse. Am J Med Sci. Aug 2003;326(2):89-93. [Medline].

  34. Gines P, Berl T, Bernardi M, et al. Hyponatremia in cirrhosis: from pathogenesis to treatment. Hepatology. Sep 1998;28(3):851-64. [Medline].

  35. Glassock RJ, Cohen AH, Danovitch G, Parsa KP. Human immunodeficiency virus (HIV) infection and the kidney. Ann Intern Med. Jan 1 1990;112(1):35-49. [Medline].

  36. Konstam MA, Gheorghiade M, Burnett JC Jr, Grinfeld L, Maggioni AP, Swedberg K. Effects of oral tolvaptan in patients hospitalized for worsening heart failure: the EVEREST Outcome Trial. JAMA. Mar 28 2007;297(12):1319-31. [Medline].

  37. Pham PC, Pham PM, Pham PT. Vasopressin excess and hyponatremia. Am J Kidney Dis. May 2006;47(5):727-37. [Medline].

  38. Santos BC, Chevaile A, Hebert MJ, Zagajeski J, Gullans SR. A combination of NaCl and urea enhances survival of IMCD cells to hyperosmolality. Am J Physiol. Jun 1998;274(6 Pt 2):F1167-73. [Medline].

  39. Schrier RW, Abraham WT. Hormones and hemodynamics in heart failure. N Engl J Med. Aug 19 1999;341(8):577-85. [Medline].

  40. Schrier RW, Gross P, Gheorghiade M, et al. Tolvaptan, a selective oral vasopressin V2-receptor antagonist, for hyponatremia. N Engl J Med. Nov 16 2006;355(20):2099-112. [Medline].

  41. Silver SM, Kozlowski SA, Baer JE, Rogers SJ, Sterns RH. Glycine-induced hyponatremia in the rat: a model of post-prostatectomy syndrome. Kidney Int. Jan 1995;47(1):262-8. [Medline].

  42. Silver SM, Schroeder BM, Bernstein P, Sterns RH. Brain adaptation to acute hyponatremia in young rats. Am J Physiol. Jun 1999;276(6 Pt 2):R1595-9. [Medline].

  43. Sterns RH. The syndrome of inappropriate antidiuretic hormone secretion of unknown origin. Am J Kidney Dis. Jan 1999;33(1):161-3; discussion 163-5. [Medline].

 
Previous
Next
 
 
 
 
All material on this website is protected by copyright, Copyright © 1994-2012 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.

DISCLAIMER: The content of this Website is not influenced by sponsors. The site is designed primarily for use by qualified physicians and other medical professionals. The information contained herein should NOT be used as a substitute for the advice of an appropriately qualified and licensed physician or other health care provider. The information provided here is for educational and informational purposes only. In no way should it be considered as offering medical advice. Please check with a physician if you suspect you are ill.