Electrolytes (sodium, potassium, chloride and bicarbonate)
The electrolyte balance in the body is dependent on food and fluid intake, and excretion by the kidney. Abnormal results can be found in some physiological conditions affecting intake and output, such as dehydration and severe diarrhoea. Kidney dysfunction may also result in abnormal electrolyte levels. Medication for hypertension and heart diseases may also affect electrolytes levels.
Excessive loss of sodium poor body fluids would result in an increase in serum sodium. This occurs in conditions such as profuse sweating, severe diarrhoea or vomiting, increased urine output (as in diabetes mellitus or insipidus), and in cases of inadequate water intake.
A decrease in serum sodium may result from excessive intake of free water or hypotonic solutions in cases of fluid replacement following sweating, diarrhoea, vomiting and excessive intake of diuretic drugs.
Medication for hypertension and heart diseases may also affect serum sodium levels.
Elevated serum potassium is seen in conditions where there is excessive destruction of human cells. Cell destruction occurs in conditions such as massive haemolysis (break down of red blood cells), crush injuries and malignant hyperpyrexia. Other conditions such as dehydration, shock with tissue hypoxia, diabetic ketoacidosis and leukocytosis may cause elevated serum potassium. Decrease in serum potassium occurs in condition where there is excess potassium loss such as in vomiting, diarrhoea and some kidney disorders.
Certain drugs can also give rise to abnormal serum potassium levels.
Dehydration, kidney dysfunction and prolonged diarrhoea are some of the conditions that may lead to an increase or decrease in serum chloride level.
The serum bicarbonate level is dependant upon clearance of carbon dioxide from the blood as well the amount of acid or base formed in or added to the body. Abnormal serum bicarbonate levels are associated with some types of breathing problems. Certain drugs may also affect serum bicarbonate levels.