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Low sodium level in the blood

Blood test
Low sodium level in the blood
Last update: 16/03/2020

What is low sodium level in blood called?

  • Hyponatremia

What is the normal level of sodium in the blood?

If you need to know which are the sodium reference ranges or you require more information about the role of sodium in the blood, you can visit normal sodium level in the blood

What does a low blood sodium level mean?

Sodium levels in the blood are usually given in mEq/L but sometimes you can see these values in mmol/l following the International System of Units (SI). Numeric values are similar in mmol/L or in mEq/L

If your blood sodium levels in the blood are low (hyponatremia) it can be due to a low sodium diet, but it is not common unless you are severely malnourished.

The main reason of low sodium levels in the blood is a consequence of an excessive urine sodium excretion or fluid retention by:

  • Kidney disorders
  • Hormonal imbalance like Addison's disease
  • Thiazide diuretics used for the treatment of high blood pressure

Hyponatremia appears also with heart, and liver problems. Late-stage congestive heart failure or liver diseases can cause renal retention of sodium and water. In this case it is possible the development of hyponatremia.

Hyponatremia or low sodium levels in the blood mean:

  • Mild hyponatremia (130 - 135 mEq/L in adults):

    Your sodium level in the blood is a bit low but it is not usually a cause for concern if you have not experienced any symptom.

    Take a new blood test in a few months and most probably, your sodium level in the blood will be optimal.

  • Moderate hyponatremia (125 - 130 mEq/L in adults):

    Moderate hyponatremia requires surveillance and monitoring.

    If you have high blood pressure and you take medication to prevent it, a visit to your doctor is recommended. A visit is also advisable in case you are suffering from fatigue or headache.

  • Marked hyponatremia (120 - 125 mEq/L in adults):

    Marked hyponatremia is a matter of concern and it is necessary to find out the underlying cause.

    It is common to have symptoms like dizziness, forgetfulness, gait disturbance, lethargy, headache or nausea.

    You must visit your doctor because it can be due to a kidney disorder. Probably, your doctor will advise you to perform some diagnostic test.

  • Severe hyponatremia (< 120 mEq/L in adults):

    The consequences of severe hyponatremia may be dangerous, including irreversible damage in the brain.

    You need to look for urgent medical attention.

    You can experience seizures, vomiting, severe confusion and ultimately coma.

Which factors can reduce sodium blood levels?

There are some circumstances or drugs than can reduce your sodium blood levels:

  • Ascites (abnormal buildup of fluid in the abdomen)
  • Pleural effusion (excess fluid that accumulates in the pleural cavity)
  • Dehydration (due to excessive sweating, vomiting or diarrhea)
  • Burns
  • Drugs
    • Anti-diabetic medication
      • Chlorpropamide
    • Antiepileptic drugs
      • Carbamazepine
    • Diuretics
      • Thiazides
    • Angiotensin-converting-enzyme inhibitors (ACE inhibitors)
    • Opiate
      • Morphine

Which diseases can reduce your sodium blood levels?

What can I do to increase sodium blood levels?

If your sodium blood level is a bit low, the following tips can help you:

  • Reduction of water and fluid intake.
  • If you take diuretic medication to treat high blood pressure you should visit your doctor and tell him about it. It is possible that he can give you alternative medication or reduce the dose.

If your blood sodium level is very low and the medical staff thinks it appropriate you may need intravenous (IV) sodium treatment to get your sodium levels back.

Where can I find more information about sodium in the blood?

You can visit our pages about:

Which values are considered a low sodium level in the blood?

The following values are considered to be below the normal range:

IMPORTANT: These levels are expressed in mEq/L (mmol/L). They are an example of a healthy man of about 45 years of age with no known disease, not taking any medication and with an appropriate intake of sodium in the diet. The ranges can be different depending on the laboratory or on your personal circumstances.

Mild hyponatremia
134 mEq/l133 mEq/l132 mEq/l131 mEq/l130 mEq/l   
Moderate hyponatremia
129 mEq/l128 mEq/l127 mEq/l126 mEq/l125 mEq/l   
Marked hyponatremia
124 mEq/l123 mEq/l122 mEq/l121 mEq/l120 mEq/l   
Severe hyponatremia
119 mEq/l118 mEq/l117 mEq/l116 mEq/l115 mEq/l114 mEq/l113 mEq/l112 mEq/l
111 mEq/l110 mEq/l109 mEq/l108 mEq/l107 mEq/l106 mEq/l105 mEq/l104 mEq/l
103 mEq/l102 mEq/l101 mEq/l100 mEq/l    
Medically reviewed by Javier Muga Bustamante Ph.D. on 16/03/2020


  • Concise Book of Medical Laboratory Technology: Methods and Interpretations. 2nd Edition. 2015. Ramnik Sood. ISBN: 978-93-5152-333-8. Pag. 560.
  • Tietz. Fundamentals of Clinical Chemistry. Carl A. Burtis, Edward R. Ashwood, David E. Bruns, Barbara G. Sawyer. WB Saunders Company, 2008. Pag 432. ISBN: 978-0-7216-3865-2.
  • Common Terminology Criteria for Adverse Events (CTCAE). Version 5.0.Published: November 27, 2017. U.S. Department of health and human Services. Available on:
  • Tietz NW, ed. Clinical guide to laboratory tests, 3rd ed. Philadelphia: WB Saunders Company,1995:124pp, 502-504,562-564.
  • Matsubara A, Ichihara K, Fukutani S. Determination of reference intervals for 26 commonly measured biochemical analytes with consideration of long-term within-individual variation. Clin Chem Lab Med 2008;46:691-98.

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