A chloride level of 108 is slightly above the standard adult reference range of 98 to 106 mmol/L, but it is not dangerously high. In most cases, a reading this close to the upper limit reflects something temporary and correctable, like dehydration, rather than a serious underlying condition. That said, it does technically qualify as hyperchloremia (elevated chloride), so it’s worth understanding what could be driving it.
Why 108 May or May Not Be Flagged
Different laboratories use slightly different reference ranges depending on their equipment and testing methods. The most commonly cited adult range is 98 to 106 mmol/L. By that standard, 108 is mildly elevated. However, Mayo Clinic Laboratories lists its adult upper limit at 107 mmol/L, and for children aged 1 to 17, the normal range extends all the way to 112 mmol/L. So depending on which lab processed your blood, 108 might appear with a bold “H” flag next to it, or it might barely register as noteworthy.
It’s also worth knowing that certain substances in the blood can interfere with the electrode used to measure chloride, producing a falsely high reading. This is uncommon, but it means a single result of 108 isn’t always the final word.
What Chloride Does in Your Body
Chloride is one of the main electrolytes in your blood. It works alongside sodium and bicarbonate to maintain fluid balance, regulate blood pressure, and keep your blood at the right pH. Your kidneys are constantly fine-tuning how much chloride you retain or excrete, so the level shifts throughout the day based on what you eat, drink, and how hydrated you are.
When chloride rises too high relative to bicarbonate, it can tip the blood toward being more acidic than normal. This is called hyperchloremic acidosis. At a level of 108, this shift would be very mild if present at all, but it’s the reason doctors pay attention to chloride in the context of your other electrolytes rather than in isolation.
Common Causes of a Mildly Elevated Reading
The most frequent reason for a chloride level in the 107 to 110 range is simple dehydration. When your body loses water (through not drinking enough, sweating heavily, vomiting, or diarrhea), the chloride in your blood becomes more concentrated. Rehydrating often brings the number back into range on the next blood draw.
Certain medications can also push chloride up. Diuretics, which increase urination, sometimes alter electrolyte balance in ways that raise chloride. Acetazolamide, a medication used for glaucoma and altitude sickness, can cause the kidneys to reabsorb more chloride than usual. If you started a new medication before your blood work, that’s a reasonable explanation to explore.
Other possible contributors include:
- Severe or prolonged diarrhea, which causes the body to lose bicarbonate, shifting the chloride-to-bicarbonate ratio
- High salt intake, since table salt is sodium chloride
- Kidney problems that affect how well the kidneys filter and excrete chloride
- Overuse of laxatives, which can deplete bicarbonate and indirectly raise chloride levels
What Your Doctor Looks At Alongside Chloride
A chloride level on its own doesn’t tell the full story. Doctors interpret it as part of a basic metabolic panel, which also includes sodium, potassium, bicarbonate (sometimes listed as CO2), and kidney function markers. The relationship between these values matters more than any single number.
For example, if your sodium is also slightly high and your bicarbonate is normal, dehydration is the most likely explanation. If your bicarbonate is low while chloride is high, that pattern points toward hyperchloremic acidosis, and your doctor will want to find out why. A chloride of 108 with every other value in the normal range is rarely a cause for concern on its own.
What a Level of 108 Feels Like
Mildly elevated chloride usually doesn’t produce noticeable symptoms by itself. If it’s driven by dehydration, you might feel thirsty, fatigued, or lightheaded. If there’s an underlying acid-base imbalance, symptoms like rapid breathing, nausea, or general weakness can develop, but these typically accompany chloride levels that are significantly higher or that persist over time. Most people with a reading of 108 feel completely fine and only discover it through routine lab work.
What You Can Do About It
If dehydration is the likely culprit, increasing your water intake over the next few days is the simplest fix. Aim for steady hydration throughout the day rather than drinking large amounts all at once. Cutting back on highly salted foods can also help, since every gram of table salt delivers chloride along with sodium.
If you’re taking a medication known to raise chloride, don’t stop it on your own. Your doctor can weigh the benefit of the medication against the mild electrolyte shift and decide whether an adjustment makes sense. In many cases, a repeat blood test after a few weeks of better hydration shows the level has normalized without any other intervention.
A chloride of 108 in an adult is the kind of result that warrants a brief conversation with your provider and possibly a recheck, not urgent worry. It sits just 2 points above the most commonly used upper limit, and temporary factors explain it more often than chronic conditions do.