Ask an expert: Biochemist

David Card uses chemistry techniques to help doctors with their diagnosis. He was our resident expert for a month, and school pupils had the chance to ask him some questions about his life and work.

What is the difference between biochemistry and biology at school?

At school biochemistry was a small part of A-level biology and was not covered at all at GCSE. Basically it involves using the structural methods of chemistry to understand how complex biological systems work. For example how enzymes can change one compound in to another or how organisms can use oxygen water and carbohydrates to generate energy.

How long did it take to become a clinical scientist?

I'm still a trainee at the moment. For most clinical scientist posts to become fully qualified you need to train for about four years at work after completion of your degree. Although you never really stop learning in this job which helps keep it interesting.

Did you find it easy to get a job overseas with your degree and experience?

When I got my first job in Sweden I had no experience. Getting your first job after your degree is often the hardest part of any career, getting the best possible degree ideally with a masters or PhD is essential.

Sweden is one of those countries where English is widely spoken so it was possible to get a job without knowing much Swedish. This isn’t the case in most countries so if you decide to work in a non English speaking country then a good grasp of the language is essential.

Why are babies routinely given vitamin K at birth? Are there any potential negative side effects/risks?

Vitamin K deficiency bleeding affects between 0.25%–1.7% of newborn babies. Giving the vitamin at birth is called a prophylaxis which means it’s a preventative measure to stop babies from bleeding.

It’s a controversial area as a study once found that giving vitamin K at birth increased the risk of childhood leukaemia. The findings were published in a daily newspaper prompting widespread public concern. As a result, some parents refused to allow their children to have vitamin K at birth putting their infant at risk of bleeding.

This study was small and its findings have not been substantiated since it was published. The panic was due to the media reporting the study without first checking the validity of the study’s data which, unfortunately, is often how the media reports science these days. Generally the current consensus is that the overall benefits of giving vitamin K at birth far outweigh any possible risk that may (or may not) exist.

If you have any concerns about this you should speak to your GP.

What type of nutritional disorders are linked to Vitamin K deficiency?

The major sign of vitamin K deficiency is failure of the blood to clot. However, long term sub-clinical (without symptoms) deficiency is believed to result in weakening of the bones and calcification (hardening) of the arteries which can lead to osteoporosis and vascular disease respectively. Vitamin K deficiency can result from a number of causes such as malnutrition, malabsorption, bile insufficiency, bowel resection and liver disease.

How do you use your Biochemistry knowledge in the analysis?

Knowledge of basic chemistry, biochemisty, genetics and medicine are essential. However, the biology units I did at school and university were less useful e.g. ecology, evolution, anatomy etc.

What is the method of immunoassay and how does it help with finding out what substances are in the blood?

Immunoassay is a test that helps us measure the concentration of a substance in a biological liquid such as urine or blood.

In our laboratory we use an enzyme linked immunosorbant assay (ELISA) which generates a signal using the enzyme horse radish peroxidase.

What do the different vitamin amounts mean once the immunoassay is complete?

In order to interpret the concentrations of vitamins in blood we use what is known as a reference range. This is the measurement of the vitamin in the blood of healthy volunteers so when we get a value lower than what we found in normal people we can suggest a diagnosis of deficiency.

These reference ranges are often open to interpretation and sometimes the best value is not what you find in normal people. For example, in Scotland it is believed many normal healthy people have sub-optimal vitamin D levels due to the lack of sunlight, which the body uses to make the vitamin in the skin.

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