sodium and chloride-common data for the parameters, indications for investigation, principles of the analytical methods, reference range, result interpretation.
Na most common cation in ECF, involved in: ECF balance, nerve impulse transmission, muscle contraction. Regulated by: salt intake, urinary output, aldosterone
Range: 135 – 155 mmol/l
Indication for investigation for Na:
Disturbances in water electrolyte balance, Polyuria and polydipsia, Disturbances in acid-base balance, Kidney diseases, Hypertension, oedemas, some endocrine diseases, hypothyroidism, Increased or decreased secretion of mineralocorticoids
Principles of the analytical methods for Na.
- Flame photometry: based on light emitted when metal ions tested to show which are present and how much. Different metal ions give a different colour and intensity due to concentration.
- Potentiometer: used to measure voltage
- Spectrophotometry: used to measure the amount of light absorbed by substance
Result interpretation for Na:
loss or gain of Na means loss or gain of water
Hypernatremia due to: kidney problems, Loss of water with the kidneys /impaired secretion of ADH, diarrhea, high salt intake.
Hyponatremia due to: diuretic drugs, vomiting, diarrhoea, deficiency in mineralocorticoids and glucocorticoids.
Chloride range: 95-105 mmol/l
Indication for investigation for Cl: Disturbances in acid-base balance, Disturbances in water electrolyte balance, Emergency cases
Principles of the analytical methods for Cl
- Potentiometer: used to measure voltage
- Spectrophotometry: used to measure the amount of light absorbed by substance
- Coulometric titration: titration using current to measure Cl
- mercurimetric titration: measures Cl
Result interpretation for Cl:
Hypochloraemia due to: loss of HCL with vomiting, diarrhoea, diuretics, Cushing syndrome, Hyperchloremia due to: chronic hyperventilation, renal tubular acidosis and infusion of chlorides