Hypertonic saline, isotonic saline, water restriction, long loops diuretics, urea or vaptans to treat hyponatremia

ABSTRACT

Introduction: Hyponatremia is the most common fluid and electrolyte abnormality. It is associated with much higher morbidity and mortality rates than found in non hyponatremic patients.

Areas covered: When the physician is faced to a hyponatremic patient he first has to confirm that hyponatremia is associated with hypoosmolality. Then he must answer to a series of questions: What is its origin? Is it acute or chronic? Which treatment is the most appropriate? We will discuss the various options for the treatment of hypotonic hyponatremia. For a better comprehensive approach of the treatment we will also discuss some pathophysiological data. The use of urea in euvolemic and hypervolemic hyponatremia will be particularly discussed. Literature was reviewed from Jan 1970 to Dec 2019.

Expert opinion: Prospective studies showing the benefit in decreasing morbidity by increasing SNa in patients with chronic hyponatremia should be done. These studies should also compare the efficacy and side effects of urea therapy compare to vaptans.

KEYWORDS:

• Hyponatremia
• furosemide
• urea
• vaptans
• hypertonic saline
• ODS
• uric acid
• bicarbonate

Article highlights

• Acute symptomatic hyponatremia is an emergency and must be treated by hypertonic saline.

• Chronic asymptomatic hyponatremia is associated with gait unsteadiness, attention deficit, fall, and bone fractures.

• Chronic hyponatremia induces osteoporosis.

• The most frequent origin of hyponatremia is SIADH which is frequently idiopathic in the elderly.

• In SIADH, around 20% of the patients could be treated by mild water restriction (<1.5-2 l/day). These patients have usually a 24 h urine volume larger than 2 l/day and a urine osmolality lower than 400 mOsm/kg H₂O.

• Increasing diuresis, with the target to decrease the excess of water, can be done by loop diuretics, urea, or vaptan.

• Oral urea induces an osmotic diuresis that can be used in the long term without toxicity. Urea acts rapidly and is able to decrease intracranial pressure. Urea has no drug interaction.

• Urea protects the brain against ODS.

• Vaptans (Tolvaptan) do not have a taste problem and they increase SNa in euvolemic and hypervolemic hyponatremia. Vaptans could rarely have some hepatotoxicity.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded.