Organ Function Testing Completed Confidence Ex. Reading Module MBC BY3BC1 = Things to do: o Type Lecture Learning Objectives: . How do Biomedical Scientists use biochemical tests? · How do we identify abnormal results? · How good is a particular test at providing a diagnosis? What do we use Biochemical Tests/Biomarkers for? · Diagnosis · e.g if you knew there was a particular protein that would appear in the blood if an organ was deteriorating . we could run a test to quantify the level of that protein · HIV - look at the quantity of virus particulars · Management · Progression of disease . can look at the number of viruses during the · Response to treatment . look at how the patient is going with the treatment · Recurrence of disease Organ Function Testing 1
· Screening - detection in asymptomatic individuals · population - newborn screening · selected group - obese patients for type II diabetes mellitus · Individual - familial hypercholesterolaemia Biomarkers · Biochemical tests use biomarkers . Usually measured in blood but can be in urine, faces or cerebral spinal fluid (CSF) · Biomarkers can be enzymes, metabolites or hormones · tend to be metabolites when a disease alters a biological mechanism - increase in byproduct · hormones: type II diabetes - disregulations of insulin . lons or gases are often also measured in Clinical Biochemistry Serum proteins / enzymes as biomarkers . in normal tissue the cells membrane is intact and the enzymes is safe inside the cell . if the cell becomes damaged, the cell membrane will become leaky causing the enzyme to escape . the high levels of this enzyme can be used to identify there is damage · but there are problems with this approach · if there is naturally a high cell number = high serum enzyme activity · when an external events causes an increase the conc. of the enzyme · too much to drink, liver will increase production of alcohol dehydrogenase · does not mean the liver is damaged · this argument applies to non-enzyme proteins in serum e.g. albumin What makes an ideal biomarker? Organ Function Testing 2
· Tissue specific · e.g. you would want to detect a specific protein that is released from only one organ . Rapid release in response to damage · needs to be released within a set number of hours . don't want something that increases rapidly and then decrease after about half an hour . Very low in serum of normal individuals . Low basal concentration . Easily measured with clear universal reference values · If these criteria are difficult to achieve use a battery of tests to make a profile · realistically it is hard to meet all these criteria · so we run multiple tests Metabolites as biomarkers · Useful to assess the function of the organ that produces them · However many metabolites are not "organ specific" . The concentration in serum may depend on uptake by