From Health Facts
Sodium constitutes 90% of the electrolyte fluid and is the most prevalent cation in the extra-cellular fluid. It is a major part of the sodium-potassium pump, facilitating cellular transport. It also acts as the main base of the blood and functions in maintaining osmotic pressure, acid-base balance, aiding in nerve impulse transmission, as well as renal, cardiac, and adrenal functions.,
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Serum sodium changes tend to be affected more by changes in fluid balance, body water and functional issue such as adrenal dysfunction, than by changes in sodium/salt balance. Urinary sodium is considered to be a more sensitive indicator of altered sodium/salt balance than blood.
Mechanisms for maintaining a constant and steady level of plasma and extracellular sodium include:
- Renal blood flow
- Carbonic anhydrase enzymatic activity
- Renin enzymatic secretion
- Antidiueretic hormone (ADH)/Vasopressin
- Food or fluid is not restricted.
- Factors which can cause increased levels
- recent trauma, surgery, or shock
- Drugs: anabolic steroids, antibiotics, clonidine, corticosteroids, cough medicines, laxatives, methyldopa, carbenicillin, estrogens, oral contraceptives, NSAIDS, aspirin, anti-hypertensives, laxatives
- Factors which can cause decreased levels
Ranges: The following are the reference ranges for this lab. However, lab ranges can vary by laboratory and country. 
|Standard U.S. Units||Standard International Units|
|Conventional Laboratory Range||135-145 mEq/L||135-145 mmol/L|
|Optimal Range||135-142 mEq/L||135-142 mmol/L|
|Alarm Ranges||<125 or >155 mEq/L||<125 or >155 mmol/L|
High levels indicate:
- Adrenal hyperfunction
- Cushing's disease
- Other conditions: water softeners, high salt intake, licorice, calcium, fluorides, and iron, renal insufficiency, diabetes insipidus, primary aldosteronism
Low levels indicate:
- Adrenal hypofunction
- Addison's disease
- Other conditions: Low salt intake ( use Celtic or sea salt instead of table salt), pyloric spasm/ obstruction, diarrhea & vomiting, excess perspiration, diabetes, Renal dysfunction, CHF
- Drugs such as diuretics
- BUN, Creatinine, Serum Potassium, Chloride, CO2, anion gap, uric acid, salivary and plasma cortisol.
- ↑ Pagana Kathleen D, Pagana Timothy J (1998) Mosby's Manual of Diagnostic and Laboratory Tests, Mosby, Inc
- ↑ 2.0 2.1 Weatherby Dicken, Ferguson Scott (2002) Blood Chemistry and CBC Analysis: Clinical Laboratory Testing from a Functional Perspective, Bear Mountain