The Performance Blood Test: Stephen Chandiwana Edition

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.

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.

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

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

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.

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.

A calculated ratio of testosterone to SHBG, giving a quick picture of androgen activity. Particularly useful in women's hormone assessment.

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

The main and most active oestrogen. In women it varies dramatically through the cycle, in pregnancy, and around menopause. In men it sits much lower but still has roles in bone, brain and cardiovascular health.

A pituitary hormone best known for its role in lactation, but it also influences reproductive function, libido and metabolism in everyone. Levels can rise temporarily with stress, exercise and sleep.

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.

An enzyme released when muscle is damaged. Levels routinely spike for 24-72 hours after heavy training, hard cardio, or any unusually intense session. We ask you to avoid heavy training before testing for this reason.

The calculated amount of biologically active testosterone, derived from total testosterone, SHBG and albumin. Often more informative than total testosterone for symptoms.

The proportion of testosterone that isn't bound to carrier proteins, making it biologically active. A more nuanced view than total testosterone alone.

The active thyroid hormone, the one actually doing the work in your cells. T3 influences metabolic rate, energy, body temperature, mood and heart rate.

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

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 percentage of your PSA that's the free type versus the total. Helps refine what your PSA result actually means. Higher percentages are generally reassuring.

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.

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.

The most abundant protein made by your liver. It transports hormones and nutrients around the body and helps regulate fluid balance. Low albumin can reflect liver, kidney, gut or nutritional factors.

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.

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

Proteins that play a major role in immunity, clotting and transport. Calculated by subtracting albumin from total protein. Patterns here can signal immune or inflammatory activity.

The combined amount of albumin and globulin in your blood. It's a broad picture of protein status, used together with albumin and globulin to spot imbalances.

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.

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.

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 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.

A widely used cardiovascular risk indicator. Lower is generally better. The ratio shifts with diet, training, weight changes and consistent aerobic exercise.

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.

Total cholesterol minus HDL. Captures every cholesterol type that can contribute to artery build-up in one figure, which is why many clinicians now prefer it as a single risk indicator.

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.