Your kidneys are responsible for removing waste products and excess fluid from your blood. How well they are doing their job can be measured by examining the levels of waste product in the blood as well as levels of electrolytes which regulate fluid in the body. Kidney disease has few symptoms in the early stages so it is important to monitor kidney function, especially if you are a diabetic, have raised blood pressure or a close relative with the disease.

Iron is an element that we require for several different bodily processes such as creating new red blood cells, carrying oxygen around the body and strengthening our immune system. Most of the iron in our bodies is found in haemoglobin, a protein in our red blood cells. A smaller proportion is stored in a protein called ferritin that is responsible for controlling the release of iron when levels are too low or high. Iron status tests measure the total amount of iron in the blood with a view to diagnosing anaemia or iron overload (haemochromatosis). They also test your body's ability to absorb iron as well as the amount of iron stored in your body.

Vitamins are essential nutrients that your body needs to function properly. You cannot make them yourself, so they need to come from the food you eat. Vitamins divide into two types: fat soluble and water soluble. Fat soluble vitamins, like vitamins A, D, E and K are found in oily foods, whether animal or plant-based. They are stored in the fatty tissue in your body as well as the liver, and therefore you don't need to eat them daily. Most water based vitamins like vitamin C are not stored in the body, and therefore you need to eat foods which contain them more frequently. You should get all the vitamins you need from a balanced diet. Sometimes, however, dietary choices or health problems can lead us to be deficient in some vitamins.

Creatine kinase (CK) is an important enzyme in tissues that have a fast metabolism, including muscle tissue. Sport and competitive training imposes substantial mechanical stresses on your body and one of the most prominent by-products of this is CK, which leaks into the blood when your muscle fibres are damaged from repeated, intense contractions. Traditionally in medicine, CK has been a marker of serious muscle injury due to a variety of mechanisms. High levels can be dangerous and can accumulate to cause a nasty condition called ‘rhabdomyolysis’. This is when so much muscle breaks down that the CK by-product can make you sick and even cause kidney failure and heart attack. However, for the athlete muscle breakdown is key to the anabolic process and so instead of breaking your muscle down by accident, you're breaking it down on purpose and as a result an athlete’s body adapts to deal with far higher levels of CK than the average person. An understanding of healthy CK levels is important as it can give measures of capacity for increased training load or flags about over-training and need to reduce load. If you are a muscle building athlete and your CK level is on the low side of the normal range, then technically you can increase your workload for faster, larger gains in performance without overloading your system (from a CK point of view!). If you CK level is too high then it’s an important alarm bell to reduce your training load to prevent severe muscle injury, overtraining syndrome and possibly kidney damage. To make sure you get the right result always ensure you test your CK level at least 2 days post-heavy exercise to get your baseline.

Inflammation occurs when your defence system is activated to rid your body of foreign invaders or irritants and to protect against tissue damage. Typical signs of inflammation include heat, redness, swelling and pain. Inflammation can be acute or chronic. Acute inflammation is often caused by infection or injury, and it flares up and disappears within days. Chronic inflammation is caused by longer-term conditions such as arthritis, inflammatory bowel disease or asthma. Inflammation causes levels of certain proteins in the blood to rise and these can be measured to assess the extent of inflammation as well as in some instances the cause.