28/10/2014 to 4/11/2014

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Ms. Tiffany was offered a position of

Executive Officer in a public enterprise.

One of the requirements for confirming

her position was a Certificate of Medical

Fitness. She visited her doctor and was

told that she would do some Chemical

Pathology laboratory investigations. The

doctor filled out a laboratory form

requesting for fasting blood glucose, lipid

profile, liver, thyroid, adrenal and renal

function tests, urine analysis and a

screen test for HIV. She was puzzled, as

she did not understand the meanings of

these medical terms. She , however,

went to the laboratory department of the

Eric Williams Medical Sciences Complex

and inquired as to the type of biological

specimens required for the tests.

Unfamiliar terms

Chemical pathology- the study of the biochemical

basis of disease and the application of biochemical

and molecular techniques in diagnosis.

Fasting blood glucose- a check of a person’s blood

glucose level after the person has not eaten for 8-12

hours.

Lipid profile- a group of tests that measures the

levels of cholesterol and triglycerides and is used to

assess the risk of developing cardiovascular disease

and monitor treatment.

Liver function test- common tests that are used to

determine how well the liver is working e.g. ALP,

albumin, urine and bilirubin.

Thyroid function tests- test used to determine how

well the thyroid produces its hormones; levels of

TSH, T3, T4 and TGB can be used.

Renal function test- test used to determine the

kidney’s efficiency.

Urine analysis (urinalysis)- analysis of the urine by

physical, chemical and microscopic means to test

for the presence of disease, drugs and other

substances.

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• Discuss what comprises the Certificate of Medical Fitness.

• Discuss the chemical pathology laboratory tests; their ranges and uses.

• Discuss the type of biological specimens needed for the tests.

• Discuss quantitative and qualitative tests.

• Discuss the difference between diagnostic and screen tests.

• Discuss the factors that affect the interpretation and chemical pathology results (age, time of sample collection, gender and diurnal variation).

• Discuss important items of information required on a laboratory request form. 3

• This is a pre-requisite for certain employment.

• It is important;

-to ensure that the job candidate is healthy and can perform the duties that are required of them on the job

-to initiate a record on the employee, this can be useful in the case of health emergencies

-for insurance purposes

-for determining the nature of a condition that may affect safety and efficiency of the applicant

-to ensure that employees are treated fairly (in the case of a disabled person provisions such as brailed document , for example, can be supplied)

-to adjudicate claims of discrimination under the Rehabilitation Act of 1973, as amended

• Each certificate of medical fitness is tailored to meet the requirements of the company or institution to which an applicant applies.

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• Bodily fluids such as blood, urine, CSF,plural fluid, synovial fluid and ascetic fluidare tested

• Urine is ideally collected first but inpractice blood is the first fluid collectedfrom patient

• Determines the condition of the body bycomparing the tested values withstandard values

• Used for diagnosis (investigation thatindicates a particular metaboliccondition), prognosis (information ingiven about the course of a disease),screening (presence of a disease thatmay not have clinical manifestation) andtreatment of illness.

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Diagnostic tests

• Diagnostic tests can be performed at any time, as long as there are symptoms

and/or signs that suggest to your primary care provider that a condition or

disease may be present and a test is needed to confirm the diagnosis.

Screening tests

• Screening tests are recommended for people who don’t show symptoms and/or

signs of a condition or disease, but may be at an increased risk based on their

age, gender or other factors. Some common screening tests include Pap smears

for women and colonoscopies for people age 50 and older.

• Screening tests are preventive services that serve to detect disease in its early

stages. Early detection generally offers the best opportunity for successful

treatment.

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• Urine is collected via the midstream clean catch method

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(Hussein et al)

• Blood samples are collected into tubes by a

phlebotomist. The tubes have different coloured tops to

represent the type of test to perform on the sample.

15Figure 12: Blood Collection into Tubes with Identifying Color Tops

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(Wikipedia)17

(Wikipedia)

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• correct identification of the patient

• appropriate preparation of the patient where necessary

• collection of the specimen into an appropriate container with the correct anticoagulant or preservative

• accurate labelling of the specimen container after the sample has been collected (not before, as this carries a higher risk of a specimen being put into a container bearing another patient’s name). Primary labelling of the sample with a barcode at source reduces the risk of mislabelling in the laboratory

• rapid and secure transport to the laboratory. Some specimens need to be transported under special conditions, for example arterial blood for ‘blood gases’ in a sealed syringe in an ice-water mixture; requests for blood, urine or faecal porphyrins must be protected from light.

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Table 2: Effect of Drugs on Test Interpretations

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Fasting Blood Glucose

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Lipid Profile

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Liver Function Test

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Thyroid Function Test

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Adrenal Function Test

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Renal Function Test

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• Hussein N S, Sadiq S M, Kamaliah M D, NorAkmal A W, Gohar M N. Twenty-four-hour urine constituents in stone formers: A study from the northeast part of Peninsular Malaysia. Saudi J Kidney Dis Transpl 2013;24:630-7

• http://www.hmsa.com/help-center/screening-and-diagnostic-tests/

• https://www.inkling.com/read/marshall-clinical-biochemistry-3rd/chapter-2/factors-affecting-test-results

• http://emedicine.medscape.com/article/773832-overview

• Raffick A.R. Bowen, Alan T. Remaley2. Interferences from blood collection tube components on clinical chemistry assays. Biochemia Medica 2014;24(1):31-44. http://dx.doi.org/10.11613/BM.2014.006

• Wikipedia

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