15.7 - Urine Diagnosis

Question 1

When creatinine and glucose show up in the urine, what does this indicate?

Answer 1

Creatinine - muscle damage

Glucose - Type 1, 2 diabetes

Question 2

Why can urine be used to indicate pregnancy?

Answer 2

• 6 days post-conception as the placenta develops, a hormone called human chorionic gonadotrophin (hCG) is released and is present in the urine and blood of the mother
• Monoclonal antibodies are relied on to detect the hCG in pregnancy tests

Question 3

How are monoclonal antibodies made?

Answer 3

1. Mouse is injected with hCG so it makes the necessary antibodies
2. The B-Cells that make the antibodies removed from the spleen of the mouse and fused with myeloma (a cancer cell that rapidly divides)
3. This fusion of the B-cell and myeloma is called a hybridoma
4. The hybridoma rapidly clone and can produce millions of the antibody.

Question 4

What occurs on a pregnancy test when soaked in urine?

Answer 4

1. Wick is soaked in urine (the 1st that is passed in the morning as it will have the most amount of hCG)
2. As urine passes up the stick (by capillary action), molecules of hCG bind to complementary mobile antibodies to form a hCG/antibody complex
3. hCG/antibody complex binds to immobile (anti-hCG) antibodies at the first strip, these immobile antibodies have coloured beads attached, that will form a coloured line in the presence of antibodies.
4. The urine continues to pass to the top of the strip, the mobile antibodies (no hCG) bind to immobile antibodies and form a line there, these are anti-antibodies. This is a control strip to show whether or not the test has worked (regardless of whether the woman is pregnant or not).

Question 5

How is urine used in sport?

Answer 5

Athletes may cheat by using anabolic steroids which mimic the action of testosterone in growing muscle size. The anabolic steroids show up in urine

To test for this, the urine sample is vaporised with a solvent as is passed into a gas chromatogram and then into mass spectrometry.

Question 6

Define immunoassay

Answer 6

An immunoassay is a process for detecting or measuring specific proteins as antigens or antibodies

Question 7

How are urine tests used in drug testing?

Answer 7

Urine tests can show the identity of many drugs. The drugs or metabolites are broken down by drugs and filtered through the kidney and end up in the bladder.

A urine sample is split into 2. It is tested by an immunoassay using monoclonal antibodies. If this shows positive a second sample is run through gas chromatography and mass spectra.