In this episode, I’ll discuss the role of proactive desmopressin in the treatment of severe hyponatremia.
One of the risks of treating severe hyponatremia (serum sodium <120 mEq/L) is osmotic demyelination syndrome (ODS) resulting from overly rapid correction of the serum sodium. An overly rapid correction is an increase in serum sodium of more than 9 mEq in the first 24 hours and 18 mEq in the first 48 hours.
An inadvertent rapid correction is especially a concern if the cause of the patient’s hyponatremia is rapidly reversible. Examples of rapidly reversible causes of severe hyponatremia are:
Syndrome of inappropriate ADH secretion (SIADH)
Adrenal insufficiency
Volume depletion
Malnourishment
Excessive alcohol intake (beer potomania)
Other risk factors for overly rapid sodium correction are:
Hepatic disease
Serum sodium ≤105 mEq/L
Concurrent hypokalemia
A common theme amongst risk factors for overly rapid correction of sodium are conditions that are likely to develop a water diuresis during the course of therapy. Water diuresis results in the elimination of free water and retention of sodium, thus raising the serum sodium rapidly and putting the patient at risk of osmotic demyelination syndrome.
A reactive strategy using dextrose 5% and desmopressin (DDAVP) can be used to re-lower the serum sodium which I discussed in episode 173. However, this reactive strategy is not guaranteed to prevent the irreversible brain damage that can occur from rapid correction and osmotic demyelination syndrome.
Therefore in high-risk patients with the factors previously discussed, a proactive strategy involving giving desmopressin at the beginning of hyponatremia treatment has been recommended by several authors.
This proactive strategy ensures that the rate of sodium increase will be slow and predictable because the desmopressin will block the patient’s kidney from being able to start water diuresis. Because of this, it may be possible to reduce the frequency of serum sodium measurements from the usual every 2 hours to every 4 or 6 hours. Whether to reduce the frequency of monitoring should be a consensus decision reached among interested disciplines such as nursing, renal, pharmacy, and intensivist services.
This proactive strategy involves starting desmopressin 1 or 2 mcg IV or subcutaneously every 6 or 8 hours at the onset of sodium replacement. Desmopressin is continued for up to 48 hours or when the serum sodium reaches a safe level such as 125 mEq/L.
You can get a comprehensive training video of the treatment of severe hyponatremia from a pharmacist’s point of view as a member of my Hospital Pharmacy Academy. To learn more, go to pharmacyjoe.com/academy.
If you like this post, check out my book – A Pharmacist’s Guide to Inpatient Medical Emergencies: How to respond to code blue, rapid response calls, and other medical emergencies.