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Chloride (Cl)
Chloride is the major anion, predominantly in the extracellular spaces, where it maintains cellular
integrity by influencing osmotic pressure. Chloride determination is significant in monitoring
acid-base balance and water balance.
Principal Reason for Performing the Test
Low chloride levels are usually found in severe vomiting or diarrhea, ulcerative colitis, severe
burns, heat exhaustion, fever, and acute infections. Elevated values are found in dehydration,
hyperventilation, anemia, and cardiac decompensation.
Most Common Abnormalities Indicated by the Test
Hyperchloremia—if elevated with sodium then the same cause of hypernatremia. Without a
concurrent increase in sodium: hyperchloremic acidosis: GI or renal loss of HCO
3
.
Hypochloremia (without related change in sodium)—upper GI tract loss (vomiting).
Sample Type and Precautions
Avoid hemolysis—sample should be run as soon as possible after serum or plasma is separated
from the cells or clot. If plasma is being collected, use only lithium heparinized samples.
Do not freeze samples for use with the Catalyst One analyzer.
Complementary Tests
Sodium, potassium, and chloride should always be assayed together to determine electrolyte
balance. If sodium, potassium, chloride, and bicarbonate are measured together, accurate
assessment of metabolic acid-base physiology is possible.
Reaction Sequence
Cholesterol (CHOL)
Serum cholesterol occurs predominantly at high concentration in the esterified form; the remainder
is in the free form. Cholesterol is synthesized in the liver and other tissues and is also absorbed
in the free form from the small intestine. It is esterified in the liver and is the precursor of steroid
hormones.
Cholesterol is broken down in the liver to bile acids and eliminated via the bile duct.
Principal Reason for Performing the Test
May be a marker for cholestasis or endocrine disease, such as hypothyroidism,
hyperadrenocorticism, diabetes mellitis, as well as nephrotic syndrome.
Most Common Abnormality Indicated by the Test
Increased cholesterol—hypothyroidism, postprandial, nephrotic syndrome.
Sample Type and Precautions
Remove plasma or serum promptly from the cells or clot. Blood should not be drawn within
12 hours of a meal. If plasma is being collected, use only lithium heparinized samples.
Complementary Tests
Cholesterol measurements should not be performed in isolation but as part of a profile of tests
to investigate endocrine, hepatic, and renal disease. If high cholesterol is found in the absence
of diabetes, hepatic, or renal disease, hypothyroidism may be present. This can be evaluated by
measuring thyroid function.
Appendices
