Chloride is an electrolyte that regulates the balance of acid-base and to a certain extent, fluids inside our body. Chloride is an anion, which means it is a negatively charged electrolyte that migrates to the anode, a positively charged electrode. In fact, chloride is the main anion in our blood. The second most important being the bicarbonate.
Chloride (and bicarbonate) allow the blood pH to be maintained within a range so that excessive acid does not build up within our body. The chloride blood test, or checking the serum (blood) chloride level, is often a part of a comprehensive metabolic panel done routinely to assess the health status of an individual.
These tests also measure the levels of other electrolytes, including sodium, potassium, bicarbonate (using carbon dioxide), in the sample. Changes in the blood chloride level indicate a change in the acid-base and electrolyte balance within the body. Changes in chloride can also reflect changes in the hydration status of the individual.
Abnormal blood chloride levels are seen in many chronic conditions. Minor changes in chloride occur on a day-to-day level. Diet, hydration, intake of electrolytes, exercise, and many other factors cause changes in blood chloride level.
A high chloride level in the blood, commonly seen in dehydration results from “volume contraction”. As the body loses salt and fluid due to dehydration (e.g., from diarrhea), the kidneys respond by absorbing sodium from the urine. The chloride, in this instant, follows the sodium and blood levels of chloride can rise. Such a high level of chloride in the blood indicates contraction alkalosis.
It is important to note that the change in blood chloride level in this case is compensatory, to ensure that the loss of bicarbonate from the gut is balanced by a higher anion (in this case, chloride). Usually, this is seen after a reduction of bicarbonate (or carbon dioxide) levels in the blood. The total anion-gap in this case remains within a normal range and is called a non-anion gap metabolic acidosis.
On another note, a low blood chloride level is usually due to chloride loss from the body. This happens with dehydration where chloride is lost from the gut or due to the use of a diuretic (water pill) when chloride is lost in the urine. A low blood chloride level in this case is usually accompanied by a low sodium level on the test as well.
In general, the abnormal blood chloride tests are used to diagnose some underlying conditions. In healthy individuals, history of dehydration can be enough to put the diagnosis together. In individuals with chronic heart disease or kidney failure, these abnormal levels of chloride allow a detailed understanding of the individual’s acid base balance.
The answer depends on what symptoms the individual has. In general, testing blood chloride level does not give out a specific diagnosis unless there is a compelling history.
E.g., patients with dehydration do not necessarily need a test for diagnosis but a metabolic panel done during this clinical time can point towards how to best manage this individual. Similarly, a patient with chronic kidney disease may need routine blood chloride tests to ensure the acid-base balance in the blood is maintained with medications.
Athletes and healthy individuals do not necessarily need a blood chloride level tested. It is also important to note that as mentioned above, chloride levels in the blood can fluctuate based on the diet and fluid intake of the individual. Changes in blood chloride levels are common as the body adjusts to the changes in diet and fluid intake.
A blood test for chloride is done via a simple phlebotomy procedure (the usual way a blood sample is taken from a vein). For the sample to be correct, it is vital that an individual checks with a medical provider regarding proper hydration status and medication use prior to testing.
High chloride level in the blood is called hyperchloremia. This means that the acid base balance may be altered in the blood, possibly transiently.
Again, it is important to put together the medical history of the individual in order to fully understand and interpret the abnormal chloride level in the blood. In some situations, changes in blood chloride levels are easily explainable. In others, they may require referrals to specialists to care for patients with advanced chronic diseases of heart, kidney or liver.
Normal levels of chloride are between 98 and 107 mEQ/L. Some labs may use a slightly higher reference of 110 mEQ/L. Generally, a chloride level > 108 mEQ/L is considered high. If this is associated with a low bicarbonate level (< 22 mEQ/L), it can indicate hyperchloremic metabolic acidosis which indicates inappropriate handling of acid base status by the kidney or loss of bicarbonate from the gut.
This is usually seen in patients with some specific diseases of the kidney and measures to increase blood chloride levels may be required using supplementation with bicarbonate. Dietary changes to increase blood chloride or bicarbonate may additionally be defined by a dietitian.
Low chloride level in the blood usually accompanies low sodium levels as seen in dehydration. Typically, this involves either a loss of the chloride ion in the urine or via the gut (e.g. during diarrheal state). At times, diuretics (or water pills particularly of the thiazide class) can lead to chloride wasting in the urine and lead to an abnormally low chloride on the test.
Sometimes, low chloride levels on testing are largely from dilutional causes- as seen in patients with heart failure or liver cirrhosis. In these states, the body experiences a total free water overloaded state which can dilute solute levels of sodium and chloride. Other causes of low chloride levels in blood include Addison’s disease, heat exhaustion, excessive vomiting, etc.
If low chloride levels in the blood are from dehydration as a result of vomiting, diarrhea or diuretic use, simple sodium chloride supplementation can work. This can be either done in the form of common salt or intravenously using normal saline (which consists of 0.9% sodium chloride solution). The route of administration largely depends on the severity of status.
Severely low chloride levels in the blood indicate a significant dehydration and is typically associated with other abnormalities including kidney function test abnormalities, low potassium levels, etc. In these cases, IV hydration is preferred to oral supplementation.
Generally, if dehydration is mild, minor changes in chloride levels can improve spontaneously as the individual improves his hydration using an electrolyte powder.
Simple dietary changes can also help improve dehydration as well as hypochloremia. If low chloride level is due to water pills (diuretics), the dose may need to be reduced. If low chloride levels in the blood are due to loss of sodium in the blood, oral supplementation with salt tabs can suffice. In cases where free salt consumption is not desirable, simple foods such as broth and soup can correct the low sodium and chloride levels.
In cases where chloride levels are high, the underlying cause needs to be addressed to correct the hyperchloremia. If it is accompanied with a drop in bicarbonate level in the blood, supplementation with sodium bicarbonate (as tablets or powder) can correct the acidosis. If the hyperchloremia and metabolic acidosis is due to diarrhea, supplementation with IV fluids (with saline or IV sodium bicarbonate as a drip) can be sufficient.
If high blood chloride levels are seen with high sodium levels in the blood (e.g. in a hospitalized patient), attention needs to be directed at reducing the intravenous infusion of normal saline, which is a common cause of hyperchloremia in hospitalized patients.
Blood chloride levels on testing can fluctuate based on an individual's health, diet and hydration status. Minor fluctuations do not need to be treated. Chloride level changes in the blood indicate an individual's acid-base and electrolyte status. Changes in medications or supplementation with electrolyte powder such as MAGNAK can improve blood chloride levels in patients who are dehydrated. In the end, only a medical professional can fully evaluate an individual's condition and advise more about what specific therapy is needed, if any.
