Lowering high sodium levels in a hospital setting is a carefully controlled process that centers on replacing the water your body is missing. Normal blood sodium falls between 136 and 145 mmol/L, and levels above 145 mmol/L qualify as hypernatremia. The approach depends on how high your sodium is, what caused it, and whether the condition developed quickly or over days. The overarching goal is to bring sodium down slowly and safely, because correcting too fast carries its own serious risks.
Why Sodium Gets Too High
High sodium almost always means your body has lost more water than salt, or taken in more salt than water. In a hospital, this often happens in patients who can’t drink on their own, whether due to sedation, altered consciousness, or being on a ventilator. Certain conditions accelerate water loss: a type of hormonal disorder called diabetes insipidus causes the kidneys to flush out large volumes of dilute urine, while fever, burns, and diarrhea all pull water from the body faster than it can be replaced.
Some medications also shift the balance. Diuretics, particularly loop diuretics like furosemide, force the kidneys to excrete more sodium and water. If the water isn’t adequately replaced, sodium concentrations in the blood climb. Identifying and treating the underlying cause is just as important as the fluid replacement itself.
How Fluids Are Given
The primary treatment is giving your body back the water it’s lost. If you can drink, that’s the simplest route: plain water by mouth. When a patient can’t swallow safely or is too ill to drink enough, the medical team delivers fluids through an IV line or, less commonly, through a tube placed into the stomach.
The type of IV fluid matters. For sodium that spiked quickly (acute hypernatremia), a solution of 5% dextrose in water is typically used. This is essentially sugar water that provides “free water” once the body metabolizes the sugar, effectively diluting the sodium in your blood. For sodium that built up gradually over days or longer, a solution of half-normal saline (0.45% sodium chloride) is more commonly chosen. In cases where the patient also has low blood volume or unstable blood pressure, a round of normal saline may come first to stabilize circulation before switching to a lower-sodium fluid.
Clinicians calculate something called a “free water deficit” to estimate how much fluid you need. This formula accounts for your body weight and current sodium level. Research has shown that the standard version of this equation tends to underestimate actual water losses by 1.5 to 2.5 liters, so medical teams also factor in ongoing losses from urine, sweat, breathing, and any drains or wounds.
The Speed Limit for Correction
This is the single most important safety consideration. Bringing sodium down too quickly can cause brain cells to swell with water, leading to cerebral edema. Symptoms of overcorrection include confusion, seizures, and in severe cases, coma or death.
Current guidelines call for lowering sodium by no more than 10 to 12 mmol/L in a 24-hour period. For chronic hypernatremia (present for more than 48 hours or of unknown duration), many clinicians aim for an even more conservative pace of 8 to 10 mmol/L per day. The brain adapts to high sodium over time by accumulating protective molecules inside its cells. If sodium drops faster than those molecules can be cleared, water rushes in and the brain swells.
When the cause developed rapidly, such as sodium spiking over just a few hours, faster correction is generally safer because the brain hasn’t had time to adapt. But in most hospital cases, the timeline is uncertain, so the slower, cautious approach is standard.
How Often Sodium Is Checked
During active correction, blood sodium is measured frequently to make sure the pace stays within safe limits. In the early hours of treatment, blood draws may happen every two to four hours. As levels stabilize, monitoring typically shifts to every six to twelve hours, then daily. For patients with ongoing risk factors, such as those with diabetes insipidus, daily sodium checks may continue even after the acute correction is complete. In one well-documented case of a patient with a rare form of diabetes insipidus, any attempt to reduce monitoring to fewer than daily checks led to rehospitalization.
Treating the Underlying Cause
Fluids address the immediate problem, but lasting correction requires treating whatever caused the sodium to rise. The approach varies widely depending on the diagnosis.
- Diabetes insipidus: When the brain doesn’t produce enough of the hormone that tells the kidneys to conserve water, a synthetic version called desmopressin replaces it. This dramatically reduces urine output and helps the body hold onto the water it receives. In some cases, thiazide diuretics or anti-inflammatory medications are added to further reduce water loss.
- Medication-related causes: If a loop diuretic or another drug triggered the imbalance, the dose may be reduced, the timing adjusted, or the medication paused entirely. For patients who still need diuretics, the medical team balances the need for the drug against adequate fluid replacement.
- Inadequate water intake: For patients who simply weren’t getting enough fluid, whether due to restricted access, impaired thirst, or difficulty swallowing, the care plan is adjusted to ensure consistent hydration going forward. This might mean scheduled water offerings, IV maintenance fluids, or a feeding tube that delivers both nutrition and water.
Dietary Sodium Restrictions
For patients whose sodium issues are part of a broader condition like heart failure, hospitals often place them on a controlled sodium diet. The most common order restricts daily intake to 2 grams of sodium, roughly equivalent to less than a teaspoon of table salt. Guidelines from heart failure organizations recommend a range of 2 to 3 grams daily for most patients. Interestingly, research has found that going below 2 grams per day doesn’t necessarily help patients with mild heart failure and may actually be associated with worse outcomes, while intake above 3 grams per day is harmful for those with moderate to severe symptoms.
In practice, a hospital’s low-sodium diet means meals prepared without added salt, avoidance of processed foods, and close attention to sodium content in broths, condiments, and even certain medications that contain sodium as a filler.
What Recovery Looks Like
For mild hypernatremia (sodium between 146 and 155 mmol/L), correction often takes one to three days with consistent fluid replacement. Severe hypernatremia, where levels exceed 160 mmol/L, can take several days to a week of careful, incremental correction. Throughout this process, symptoms like confusion, irritability, and muscle twitching typically improve as sodium levels normalize, though full neurological recovery can lag behind the lab numbers.
Patients are usually kept in the hospital until sodium is trending steadily downward within the safe correction rate and the underlying cause is either resolved or managed with a clear outpatient plan. For people with chronic conditions like diabetes insipidus, discharge planning includes a protocol for ongoing fluid intake and regular sodium monitoring at home or through outpatient labs.