Severe Hyponatremia with High Urine Sodium and Osmolality

Summary

DOI: 10.1373/clinchem.2008.125575

A 49-year-old woman (previous history of childhood asthma, no medication) presented to the emergency department with nausea and vomiting that had occurred for 5 days and slurred speech for 1 day prior to presentation. The patient denied use of alcohol and illicit drugs. Physical examination revealed her blood pressure to be 125/70 mmHg; she had no postural drop and had a regular pulse of 72 beats/min. She had no fever and no signs of contracted extracellular fluid volume. Results of further physical and neurological examination were unremarkable and revealed no goiter, pigmentation, or vitiligo. Her laboratory results are shown in Table 1⇓ . Additional diagnostic tests included chest x-ray, abdominal ultrasound, and brain computed tomography, none of which revealed abnormalities. The syndrome of inappropriate antidiuretic hormone secretion (SIADH)1 was suspected. However, fluid restriction (500 mL/day) did not lead to increased serum sodium.

Complete Article
Commentary: Glen L. Hortin,* Neil S. Harris, and William E. Winter
Commentary: Robert Richardson

Student Discussion

Student Discussion Document (pdf)

Joost van der Hoek,^1* Ewout J. Hoorn, ¹Gijs M.T. de Jong,² Emile N.W. Janssens,² and Wouter W. de Herder¹

¹Department of Internal Medicine, Erasmus MC Rotterdam, the Netherlands; ²Department of Internal Medicine; Albert Schweitzer Hospital, Dordrecht, the Netherlands.
*Address correspondence to this author at: Erasmus Medical Center, Department of Internal Medicine, P.O. Box 2040, 3000 CA Rotterdam, the Netherlands. Fax +31-10-7031146; e-mail [email protected].

Case Description

A 49-year-old woman (previous history of childhood asthma, no medication) presented to the emergency department with nausea and vomiting that had occurred for 5 days and slurred speech for 1 day prior to presentation. The patient denied use of alcohol and illicit drugs. Physical examination revealed her blood pressure to be 125/70 mmHg; she had no postural drop and had a regular pulse of 72 beats/min. She had no fever and no signs of contracted extracellular fluid volume. Results of further physical and neurological examination were unremarkable and revealed no goiter, pigmentation, or vitiligo. Her laboratory results are shown in Table 1. Additional diagnostic tests included chest x-ray, abdominal ultrasound, and brain computed tomography, none of which revealed abnormalities. The syndrome of inappropriate antidiuretic hormone secretion (SIADH) was suspected. However, fluid restriction (500 mL/day) did not lead to increased serum sodium.

Table 1 Laboratory Results

Questions to Consider

What is the differential diagnosis in a patient with severe hyponatremia and a high urine sodium and osmolality?
Name three hormones that, when disturbed, can all independently result in hyponatremia with a high urine sodium and osmolality?
What should be excluded before the diagnosis?

Final Publication and Comments

The final published version with discussion and comments from the experts appears in the November 2009 issue of Clinical Chemistry, approximately 3-4 weeks after the Student Discussion is posted.

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