Before different clinical presentations that may be suspected of fluid and electrolyte disorders, the test measures the major blood anions and cations:
– Cations are: sodium (Na), potassium (K), calcium (Ca) and magnesium (Mg);
– Anions are: chlorine (Cl), bicarbonate (HCO3) and proteins.
It is the clinical examination which must guide the application.
The review also becomes important:
– In the monitoring of metabolic disease such as diabetes, hypertension.
– From kidney or liver disease;
– If dehydration is suspected, intracellular hydration, hyper- or hypokalemia (secondary aldosteronism in HTA), but also of hyponatremia in patients on diuretics, suffering from kidney disease.
The balance of anions and cations is one of the conditions of the balance of the body, particularly its proper hydration;it is broken and the disorders may appear, biological first and clinics.
Sampling 5 mL of venous blood on heparin tube:
– Quickly send to the laboratory;
– Reduce to a minimum the time of the withers;
– Do not make a fist to the patient;
– Absolutely avoid hemolysis.
|cations||mmol / L||mEq / L||anions||mmol / L||mEq / L|
|Na (sodium)||138-145||138-145||Cl (chlorine)||95 to 105||95 to 105|
|K (potassium)||3.8 to 5||4.52||HCO3 (bicarbonate)||22-28||22-28|
|Ca (Calcium)||2.25 to 2.55||5||protein||60-80 g / L||117|
|Mg (magnesium)||0.75 to 1||2|
Sodium and potassium cations account for 95%, chlorine and bicarbonate, 85% of the anions.
The difference between cation and anion is called “anion gap”:
– It is increased in case of:
– Kidney failure with acidosis and clearance less than 10mL / min,
– Diabetic acidosis (buildup of anions)
– Lactic acidosis
– Toxic acidosis (salicylates, ethylene glycol)
– Hypocalcemia, hypogammaglobulinemias (decrease cations);
– It is reduced in case of:
– Cirrhosis (lower anions)
– nephrotic syndrome,
– Acute intoxication with lithium or IgG myeloma (cations increases).
Another parameter to consider is the measurement of plasma osmolality, which is obtained by the following calculation: osmolality = serum sodium mmol / L x 2 + glucose mmol / L + urea mmol / L:
– Its normal value of 300 mOsm / kg water;
– Plasma Hyperosmolality is due to:
– Water deficit by inadequate intake or kidney damage,
– A diabetic hyperosmolar coma, acute alcoholism, a massive ingestion of sea water;
– There are hypo-osmolality in case of:
– Taking diuretics,
– Acute adrenal insufficiency,
– Vomiting, diarrhea.
B20 Na, Cl, K
B40 plus HCO3 and protein.
The chemistry panel is disrupted in case of large or hyperlipemia hyperprotéinémies: all components are lowered; the amount of water being reduced in proportion to the additional amount of protein and or lipids.
A simple additional examination, urinary electrolytes (removal of morning urine), information on the behavior of the kidney compared to pathology observed compared to a chemistry panel disorder.