Indications:
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.
Principle:
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.
Technique:
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.
Results:
Normal values:
| 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.
Cost:
B20 Na, Cl, K
B40 plus HCO3 and protein.
Practical advice:
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.
