To achieve an effective service, a clinical biochemistry laboratory has three main
functions:- to advisethe requesting GP or hospital doctor on the appropriate tests for a particular
medical condition and on the collection, storage and transport of the patient samples
for analysis; - to providea quality analytical service for the measurement of biological analytes in an
appropriate and timely way; - to providethe requesting doctor with a data interpretation and advice service on the
outcome of the biochemical tests and possible further tests.
Table 16.1Typical reference ranges for biochemical analytes
Analyte Reference range Comment
Sodium 133–145 mM
Potassium 3.5–5.0 mM Values increased by haemolysis or prolonged contact
with cells.
Urea 3.5–6.5 mM Range varies with sex and age e.g. values up to 12.1
will be found in males over the age of 70.
Creatinine 75–115 mM (males)
58–93 mM (females)
Creatinine (a metabolite of creatine) production
relates to muscle mass and is also a reflection of renal
function. Values for both sexes increase by 5–20%
in the elderly.Aspartate
transaminase (AST)
<40 IU dm^3 Perinatal levels are<80 IU dm^3 and fall to adult values
by the age of 18. Some slightly increased values up to
60 IU dm^3 may be found in females over the age of 50.
Results are increased by haemolysis.Alanine transaminase
(ALT)
<40 IU dm^3 Higher values are found in males up to the age
of 60.Alkaline phosphatase
(AP)
<122 IU dm^3 (adults)
<455 IU dm^3 (children
<12 y)Significantly raised results of up to two- or three-fold
would be experienced during growth spurts through
teenageyears.Slightlyraisedlevelsalsoseeninthe
elderly and in women during pregnancy.Cholesterol No reference range but
recommended value of
<5.2 mM
The measurement of cholesterol in an adult ‘well’
population does not show a Gaussian distribution
but a very tailed distribution with relatively few low
results. The majority are<10 mM but there is a
long tail up to over 20 mM. There is a tendency for
males to have higher cholesterol than females of the
same age but after the menopause female values
revert to those of males. Generally values increase
with age.630 Principles of clinical biochemistry