Clinical Chemistry Laboratories
The Clinical Chemistry Laboratories provide routine analyses relying heavily on automated random access analyzers with multiple methodologies. A number of manual assays and urinalyses are also performed. Certain hormone assays, selected enzyme activity assays, serum tumor markers, various hepatitis tests, special amniotic fluid chemistries, glycosylated hemoglobin, as well as various infrequently ordered RIA, EIA and manual procedures are also provided.
Suggested reference ranges are provided for listed analytes in terms of conventional and System Internationale (SI) units. The reasons for using SI units in preference to conventional units are beyond the scope of this manual. In short, the international community of biochemists suggests using the liter (L) as the "volume" of choice and using the "mole" rather than the "gram" whenever possible in describing concentration values. However, concentration values are expressed in grams rather than moles in two general cases: 1) when the analyte being measured is a heterogenous group of compounds with differing molecular weights; and 2) when the molecular weight of the analyte being measured is not precisely known. The accepted SI unit in the case of analytes for which functional activity rather than molecular mass is measured (e.g., enzymatic activity) is the International Unit (IU) which is defined as that quantity of enzyme that will catalyze the reaction of one micromole of substrate per minute.
For those situations when the reference intervals are very dependent upon the clinical setting during which the specimen was obtained, we suggest calling the laboratory and asking for the clinical pathologist on-call for more information as to appropriate values.