15.7 Urine and Diagnosis

Question 1

In which different ways does urine help diagnosis?

Answer 1

1) Pregnancy testing
2) Testing for anabolic steroids in athletes urines
3) Testing for drugs e.g alcohol, cannabis, cocaine
4) Detecting diabetes from glucose in urine

Question 2

What does hCG stand for?

Answer 2

Human Chorionic Gonadatrophin

Question 3

What is hCG and where is it produced?

Answer 3

hCG is a hormone produced from the site of developing placenta

Question 4

Where is hCG found?

Answer 4

hCG can be found in the blood and urine of the mother.

Question 5

What are monoclonal antibodies?

Answer 5

Monoclonal antibodies are antibodies from a single clone of cells that are produced to target particular cells or chemicals in the body.

Question 6

How are monoclonal antibodies prepared?

Answer 6

1) A mouse is injected with hCG so it makes the appropriate antibody.
2) The B-cells that make the required antibody are then removed from the spleen of the mouse and fused with a myeloma, a type of cancer cell which divides rapidly.
3) This new fused cell is known as hybridoma. Each hybridoma reproduces rapidly, resulting in a million of a clones making the desired antibody.
4) These monoclonal antibodies are collecting, purified and used.

Question 7

What are the main stages in a pregnancy test?

Answer 7

1) The wick is soaked in the first urine passed in the morning- this will have the highest levels of hCG.
2) The test contains mobile monoclonal antibodies that have very small coloured beads attached to them. They will only bind to hCG. If a woman is pregnant, the hCG in her urine binds to the mobile monoclonal antibodies and forms a hCG/antibody complex.
3) The urine carries on along the test structure until it reaches a window.
4) Here there are immobilised monoclonal antibodies arranged in a line arranged in a line or a pattern such as a positive sign (+) that only binds to the hCG/antibody complex. If the woman is pregnant, a coloured line or pattern appears in the first window.
5) The urine continues up through the test to a second window.
6) Here there is usually a line of immobilised monoclonal antibodies that bind only to the mobile antibodies, regardless of whether they are bound to hCG or not. This coloured line forms regardless of whether the woman is pregnant- it simply indicates that the test is working.

Question 8

What are anabolic steroids?

Answer 8

Anabolic steroids are drugs that mimic the action of the male sex hormone testosterone and they stimulate the growth of muscles.

Question 9

How are steroids tested for?

Answer 9

• Athletes regularly have their urine tested for steroids via gas chromatography and mass spectrometry.
• The urine sample is vaporised with a known solvent and passed along a tube.
• The lining of the tube absorbs the gases and is analysed to give a chromatogram which is read to show the presence of the drugs.

Question 10

How are recreational drugs tested for?

Answer 10

1) The first sample is tested by an immunoassay, using monoclonal antibodies to bind to the drug or its breakdown product.
2) If first sample shows positive, the second sample is run through a gas chromatograph/mass spectrometer to confirm presence of drug.