Performance Monitor: 33-Marker Biological Profile

A liver enzyme that leaks into the blood when liver cells are stressed. Mildly raised ALT is common after heavy training, recent alcohol, certain medications, or fatty changes in the liver. Persistently high ALT is worth discussing with a GP.

An enzyme involved in both liver and bone activity. Levels naturally vary with age (higher in growing teens, post-fracture healing) and during pregnancy, as well as with liver function.

An enzyme that leaks into your blood when liver cells are stressed or damaged. Often looked at alongside ALT to give a clearer picture of liver health. Heavy exercise can also raise it temporarily.

A liver enzyme particularly sensitive to alcohol intake and certain medications. Useful for understanding the source when other liver markers are raised.

A yellow pigment made when old red blood cells are broken down. Slightly raised bilirubin is often a harmless inherited pattern (Gilbert's syndrome); larger elevations can reflect liver or red blood cell processes.

A waste product your muscles produce that's filtered out by your kidneys. Levels can shift with muscle mass, hydration status and protein intake, so very muscular people often sit slightly higher than the population average.

An estimate of how efficiently your kidneys filter blood, calculated from your creatinine. Higher is generally better. It's the single most-used indicator of overall kidney functio n.

Another waste product cleared by the kidneys, this one from protein breakdown. It's affected by hydration, protein intake and kidney function.

The total amount of cholesterol circulating in your blood, including both protective (HDL) and less-protective (LDL) types. On its own it tells you very little, which is why we always read it alongside HDL, LDL and the ratio below.

The cholesterol most associated with build-up in artery walls when it sits high for years. Diet (especially saturated fat), genetics, body composition and activity level all influence LDL (Low Density Lipoprotein).

The cholesterol that picks up excess from your arteries and returns it to your liver. Higher HDL is generally protective. It's influenced by exercise, alcohol intake, and the types of fat in your diet.

A form of fat your body uses for energy. Levels are heavily influenced by recent meals (which is why we ask you to fast), alcohol, carbohydrate intake and overall body composition.

A marker your liver releases when there's inflammation anywhere in the body. High CRP can reflect short-term inflammation (a recent illness, intense training, an injury) or longer-term, low-grade inflammation linked to lifestyle, sleep and stress.

The same measurement in mmol/mol, the unit the NHS and UK clinicians use. We show both so you can compare to NHS or older test results easily.

Your average blood sugar level over the past 8-12 weeks, expressed as a percentage. Often called your "glucose memory" because, unlike a single glucose reading, it can't be gamed by a recent meal or fast.

Your main stress and energy hormone, produced by your adrenal glands. It follows a strong daily rhythm: highest in the morning (which is why we ask for a morning sample) and lowest at night. Affected by sleep, training, work stress and caffeine.

The mineral your body uses to make red blood cells and carry oxygen around your body. Low iron can leave you tired, breathless, or struggling to recover from training.

Your body's stored iron, the long-term iron savings account. Low ferritin is the earliest sign of iron deficiency, often appearing before iron itself drops or anaemia develops. Common in women with heavy periods, athletes, and people on plant-based diets.

Essential for energy production, nerve function, and red blood cell formation. Found almost exclusively in animal products, so vegans and vegetarians need to supplement. Low B12 can present as fatigue, brain fog or tingling.

The vitamin your body makes from sunlight and gets from food. Affects bones, muscles, mood, and immune function. UK adults often run low in winter months.

The protein that binds sex hormones in the blood. High SHBG can reduce the amount of biologically active testosterone, even when total testosterone looks normal.

The principal male sex hormone, also important in women at lower levels. Influences muscle mass, libido, mood, energy and bone density. Levels naturally peak in the morning, which is why we ask for a morning sample.

Works alongside FSH to regulate reproductive hormones. In women, LH triggers ovulation; in men, it signals the testes to produce testosterone.

A pituitary hormone that signals the ovaries or testes. In women it varies through the menstrual cycle and rises sharply around menopause; in men it sits in a steady range.

The pituitary signal that tells your thyroid how hard to work. Counter-intuitively, high TSH usually means your thyroid is under-active (the brain is shouting at it), and low TSH often means it's over-active.

The storage form of thyroid hormone, mostly converted into T3 when needed. Most of your circulating thyroid hormone is in this T4 form.

Your immune system's army. Numbers rise temporarily during infections, after intense exercise or in response to stress. Persistently raised or low counts are worth a closer look.

How much your red blood cells vary in size. A higher RDW can be an early signal of mixed nutritional deficiencies, even before MCV moves out of range.

The cells that carry oxygen from your lungs around your body. Endurance athletes often sit slightly higher than average; pregnancy and certain conditions can lower them.

The average size of your red blood cells. Small cells can suggest iron deficiency; large cells can point to B12 or folate deficiency.

How densely packed haemoglobin is within your red blood cells. Provides extra detail when interpreting unusual full blood count patterns.

The average amount of haemoglobin inside each red blood cell. Read alongside MCV, it helps narrow down the type of any anaemia present.

The iron-containing protein inside red blood cells that actually binds and carries oxygen. Low haemoglobin (anaemia) commonly causes fatigue, breathlessness and pale skin.

The proportion of your blood that's made up of red blood cells, expressed as a percentage. A key indicator of hydration status as well as red cell health.

A measurement of the average size of your platelets. Newly produced platelets are typically larger, so this marker provides insight into how actively your bone marrow is manufacturing these crucial clotting cells to repair blood vessels.