Hyponatremia in a 46-Year-Old Man After Head Trauma

Federico J. Teran, MD; Eric E. Simon, MD; Vecihi Batuman, MD


July 19, 2017

Physical Examination

During the follow-up visit, the patient was noted to have a serum sodium concentration of 128 mEq/L and was referred to nephrology for evaluation for hyponatremia. During his visit to the nephrology clinic, the patient complained of occasional dizziness and continued pain in the neck area but had no other complaints. He was alert, oriented, and well developed and appeared in mild distress with pain, wearing a neck collar brace. His weight was 87 kg, height was 174 cm, body mass index was 28.7 kg/m2, blood pressure was 128/76 mm Hg, pulse was 87 beats/min, and heart and lung examination findings were normal. No edema was noted, and the rest of his physical examination was unremarkable.

Repeat laboratory studies showed the following:

  • Sodium level—126 mEq/L

  • Potassium level—3.9 mEq/L

  • Chloride level—93 mEq/L

  • Total CO2—23

  • Blood urea nitrogen (BUN) level—10 mg/dL

  • Creatinine level—0.6 mg/dL

  • Glucose level—99 mg/dL

  • Uric acid level—1.6 mg/dL

  • Plasma osmolality—260 mOsm/kg

Urine studies revealed the following:

  • Sodium level—173 mEq/L

  • Potassium level—45 mEq/L

  • Creatinine level—168 mg/dL

  • Uric acid level—52 mg/dL

  • Urine osmolality—565 mOsm/kg

Complete blood count findings were normal, and nonfasting lipid profile found the following:

  • Total cholesterol—223 mg/dL

  • Triglyceride level—188 mg/dL

  • Low-density lipoprotein level—170 mg/dL

  • High-density lipoprotein level—46 mg/dL

Thyroid study findings were normal.

The patient declined hospital admission for investigation and treatment of his hyponatremia because he had urgent personal matters to attend to. However, 2 days later, the patient is brought to the emergency department because of increased confusion and seizure. Repeat chemistries showed the following:

  • Serum sodium level—113 mEq/L

  • Plasma osmolality—235 mOsm/kg

  • Urine osmolality—1057 mOsm/kg

  • Urine sodium level—196 mEq/L

A CT scan of the head revealed brain edema (Figure 1). The patient is admitted to the intensive care unit and urgent treatment is initiated.

Figure 1.


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