Hyponatremia: Causes, Symptoms, and Management

When dealing with Hyponatremia, a condition where blood sodium falls below normal levels, often causing confusion, fatigue, and seizures. Also called low sodium, it can strike anyone but shows up most in patients on certain drugs or with chronic illnesses. Hyponatremia doesn’t happen in isolation; it’s closely tied to Sodium, the main extracellular electrolyte that regulates water balance, and to disorders like SIADH (syndrome of inappropriate antidiuretic hormone secretion) that trap water in the body. Another common driver is the use of diuretics, which push excess fluid out of the kidneys but can also wash out sodium.

Key Factors Behind Hyponatremia

Understanding the puzzle starts with the sodium‑water relationship. Sodium acts like a magnet for water; when its concentration drops, water moves into cells, swelling them. This swelling is why severe hyponatremia can lead to brain edema and dangerous neurological symptoms. The body’s hormonal system, especially antidiuretic hormone (ADH), decides how much water we keep. In SIADH, ADH stays high even when we’re already over‑hydrated, forcing the kidneys to reabsorb water and diluting sodium. Diuretics, on the other hand, force the kidneys to excrete both water and salt, and if the salt loss outruns water loss, sodium levels plunge.

Medication‑induced hyponatremia is a big piece of the story. Antidepressants, especially SSRIs, and some antiepileptics can trigger SIADH‑like effects. Even over‑the‑counter pain relievers sometimes meddle with kidney function, nudging sodium down. For athletes, the combination of intense sweating and excessive low‑salt sports drinks can create a rapid drop in blood sodium, a scenario known as exercise‑associated hyponatremia.

Age matters, too. Older adults often have reduced kidney function and a blunted thirst response, making them prone to both fluid overload and sodium loss. Chronic conditions like heart failure or liver cirrhosis keep the body in a fluid‑retention mode, which further dilutes sodium. In these cases, the heart or liver sends signals that raise ADH, reinforcing the cycle of low sodium.

Diagnosing hyponatremia starts with a simple blood test. The key value is serum sodium, measured in milliequivalents per liter (mEq/L). Levels under 135 mEq/L signal hyponatremia; under 120 mEq/L is considered severe and needs urgent care. Doctors also check urine sodium and osmolality to figure out whether the kidneys are dumping or holding onto salt.

Treatment hinges on how fast sodium fell and how low it is. For mild cases, fluid restriction—usually limiting intake to less than a liter a day—can let the body rebalance on its own. When SIADH is the culprit, medications like demeclocycline or newer V2‑receptor antagonists help block ADH’s effect. If a diuretic caused the issue, adjusting the dose or switching to a different class often resolves the problem.

Severe hyponatremia demands rapid correction, but not too fast. Giving hypertonic (3%) saline raises serum sodium safely, while overly rapid shifts risk a dangerous condition called osmotic demyelination syndrome. In the hospital, nurses monitor sodium levels every few hours, adjusting IV fluids based on the patient’s response.

Prevention is practical. For people on diuretics, regular blood work and diet tweaks—like adding a pinch of salt or eating potassium‑rich foods—keep sodium steady. Those on antidepressants should watch for early warning signs such as unexplained dizziness or headaches and discuss dosage changes with their doctor.

Whether you’re a patient, caregiver, or health‑curious reader, knowing the web of factors—sodium balance, hormonal control, medication effects, and underlying diseases—helps you spot hyponatremia early and act wisely. Below you’ll find a curated collection of articles that dive deeper into specific drugs, lifestyle tips, and medical guidelines, giving you actionable insights to stay on top of your electrolyte health.