Advanced Fitness Blood Test Kit

Testosterone is the primary anabolic hormone responsible for muscle building, strength gains, recovery, bone density, red blood cell production, and training motivation in both men and women (women have much lower levels but it's still important). Testosterone promotes protein synthesis and muscle growth, increases red blood cell production (improving oxygen delivery to muscles), and affects mood, drive, and competitive spirit. Low testosterone impairs muscle building, slows recovery, reduces strength and power, and causes fatigue and low motivation. In athletes, low testosterone can result from overtraining, chronic calorie restriction, inadequate sleep, excessive endurance training, or chronic stress. The testosterone:cortisol ratio helps assess whether you're recovering adequately from training. Testosterone follows a circadian rhythm—levels are highest in the morning, which is why morning testing is important. Results outside the normal range may need a follow-up with your GP.

The testosterone:cortisol (T: C) ratio indicates the balance between anabolic (muscle-building) and catabolic (muscle-breaking) processes in your body. Testosterone promotes protein synthesis and muscle growth; cortisol opposes these effects by inhibiting protein synthesis, blocking anabolic signalling, and promoting muscle breakdown. The T: C ratio is more sensitive to training stress than either hormone measured alone. A declining T: C ratio over time suggests your body isn't recovering adequately—you may be overtraining, under-recovering, chronically stressed, or not eating enough. This marker is most useful when tracked over time to see trends. Elite athletes and serious trainers use T: C ratio to help optimise training load and recovery. A single measurement provides a snapshot; serial measurements show whether your training programme is appropriate for your recovery capacity. Results outside the normal range may need a follow-up with your GP.

Total protein measures the combined amount of albumin and globulin proteins in your blood. These proteins perform vital functions including maintaining fluid balance, transporting hormones and nutrients, supporting immune function, and providing raw materials for tissue repair. For athletes, adequate protein status is essential for muscle recovery and adaptation. Abnormal total protein may indicate dehydration (artificially elevating the result by concentrating the blood), inadequate protein intake, chronic inflammation, or underlying health issues affecting protein metabolism. Very low total protein suggests malnutrition or protein losses. Results outside the normal range may need a follow-up with your GP.

Albumin is the most abundant protein in your blood, made by the liver. It maintains fluid balance (keeping fluid inside blood vessels), transports hormones, nutrients, and drugs, and supports tissue growth and healing. For athletes, albumin reflects nutritional status and liver function. Low albumin can indicate inadequate protein intake, chronic inflammation (albumin is a negative acute phase reactant—it falls during inflammation), overtraining, liver problems, or kidney problems (albumin leaking into urine). Dehydration can artificially elevate albumin by concentrating the blood. Adequate albumin is important for optimal recovery and performance. Results outside the normal range may need a follow-up with your GP.

Globulins are a diverse group of proteins including immunoglobulins (antibodies), transport proteins, and enzymes. Globulin is calculated by subtracting albumin from total protein. Immunoglobulins are produced by your immune system to fight infections. Elevated globulin can indicate chronic inflammation, chronic infection, or immune system activation—potentially from overtraining or inadequate recovery. Athletes who overtrain often have suppressed immune function reflected in their globulin levels. Low globulin can indicate immune deficiency. The albumin/globulin ratio provides additional diagnostic information about the balance between these protein groups. Results outside the normal range may need a follow-up with your GP.

Iron is essential for producing haemoglobin—the protein in red blood cells that transports oxygen from your lungs to working muscles during exercise. Iron is also needed for myoglobin (oxygen storage in muscles), energy production in mitochondria, and various enzymes. Low iron causes fatigue, reduced endurance, impaired performance, and difficulty recovering from training. Athletes have increased iron needs due to iron losses through sweat, gastrointestinal bleeding from intense exercise, and 'foot-strike haemolysis' (red blood cell destruction from repetitive impact). Endurance athletes, female athletes (due to menstrual blood loss), and athletes following restricted diets are at particular risk of iron deficiency. Serum iron fluctuates throughout the day and is affected by recent meals, so it's interpreted alongside ferritin, TIBC, and transferrin saturation for the full picture. Results outside the normal range may need a follow-up with your GP.

TIBC measures your blood's capacity to transport iron—it indirectly reflects transferrin levels, the protein that carries iron in your blood. When iron stores are depleted, your body produces more transferrin to maximise iron capture from your diet, so TIBC rises. When iron stores are adequate, less transferrin is needed and TIBC is normal or low. High TIBC with low iron and low ferritin is a classic pattern of iron deficiency—common in athletes, particularly endurance athletes and menstruating women. Low TIBC can occur with iron overload, chronic inflammation, or malnutrition. TIBC helps distinguish between different causes of abnormal iron levels and stages of iron deficiency. Results outside the normal range may need a follow-up with your GP.

Transferrin saturation indicates what percentage of your iron transport capacity is being used—calculated as (serum iron ÷ TIBC) × 100. Normal saturation is typically 20-50%. Low transferrin saturation (below 20%) indicates iron deficiency—oxygen delivery to muscles is being compromised, affecting endurance and recovery. Very high saturation (above 45-50%) is an important marker for iron overload, including hereditary haemochromatosis. Some athletes supplement iron without testing, which can lead to iron overload if they don't actually have deficiency. Iron overload causes organ damage and impairs performance. Testing before supplementing is important. Results outside the normal range may need a follow-up with your GP.

Ferritin is the storage form of iron—it reflects how much iron you have in reserve. It's often the first marker to decline in athletes developing iron deficiency, falling before serum iron or haemoglobin become abnormal. Low ferritin causes fatigue and reduced performance even before outright anaemia develops. Athletes, particularly endurance athletes and menstruating women, commonly have suboptimal ferritin. Many sports medicine practitioners suggest athletes maintain ferritin above 30 µg/L (some suggest above 50 µg/L for optimal performance), which is higher than the standard 'normal' range lower limit. Ferritin is also an acute phase reactant—it rises with inflammation, infection, and liver disease—which can mask underlying iron deficiency. If hs-CRP is elevated, ferritin may be falsely normal despite depleted iron stores. Results outside the normal range may need a follow-up with your GP.

Bilirubin is a yellow pigment produced when red blood cells break down. It's processed by the liver, stored in the gallbladder, and excreted in bile. In athletes, elevated bilirubin may indicate increased red blood cell turnover from intense training (particularly impact sports causing 'foot-strike haemolysis'), liver stress from supplements or medications, or the common harmless condition Gilbert's syndrome (present in about 5% of people, causing mildly elevated bilirubin). Gilbert's syndrome causes no health problems and requires no treatment. Very high bilirubin causing jaundice (yellow skin/eyes) warrants prompt investigation. Results outside the normal range may need a follow-up with your GP.

Alkaline phosphatase (ALP) is an enzyme found mainly in the liver and bones. In athletes, elevated ALP is often due to increased bone turnover from weight-bearing exercise and impact training rather than liver problems—this is actually a positive sign of bone remodelling and adaptation. Younger athletes in their late teens and early twenties naturally have higher ALP due to ongoing bone growth. ALP can also be elevated by liver stress from supplements, medications, or excessive alcohol. Very high ALP warrants investigation to determine whether it's from bone (usually benign in athletes) or liver (may need attention). GGT helps distinguish between these sources—if ALP is elevated but GGT is normal, the source is likely bone. Results outside the normal range may need a follow-up with your GP.

ALT is a liver enzyme that is released into the bloodstream when liver cells are damaged or inflamed. Elevated ALT can indicate liver stress from supplements (particularly some pre-workouts, fat burners, and anabolic substances), excessive alcohol consumption, fatty liver disease, medications, or viral hepatitis. For athletes, monitoring ALT helps ensure your supplement regimen isn't harming your liver. Mild elevation after intense exercise is possible due to muscle damage (ALT is also present in muscle tissue in smaller amounts), which is another reason to rest for 48 hours before testing. Persistent elevation warrants investigation and potentially reviewing your supplement use. Results outside the normal range may need a follow-up with your GP.

Gamma GT (gamma-glutamyl transferase, GGT) is a liver enzyme particularly sensitive to alcohol consumption and certain supplements. GGT helps distinguish between liver and bone causes of elevated ALP—if ALP is high and GGT is normal, the source is likely bone (often benign in athletes); if both are elevated, it suggests liver involvement. Elevated GGT may indicate liver stress from supplements, excessive alcohol consumption, bile duct problems, or metabolic issues. For athletes wanting to optimise health and performance, elevated GGT warrants review of alcohol intake and supplement regimen. Results outside the normal range may need a follow-up with your GP.

Urea is a waste product from protein breakdown that is filtered by the kidneys and excreted in urine. In athletes, elevated urea may indicate dehydration, very high protein intake, kidney stress from supplements, or increased muscle protein breakdown from intense training. Low urea can occur with inadequate protein intake, which could compromise muscle recovery and adaptation. Urea levels help assess whether your protein intake and hydration are appropriate for your training load. Interpreting urea requires context—a strength athlete eating 2g/kg protein daily will naturally have higher urea than a sedentary person. Results outside the normal range may need a follow-up with your GP.

Creatinine is a waste product from normal muscle metabolism that is filtered by the kidneys. Creatinine production is proportional to muscle mass—athletes with high muscle mass naturally have higher creatinine than sedentary individuals or those with less muscle. Creatine supplementation (common in strength athletes) also elevates creatinine. This means 'elevated' creatinine in a muscular athlete may be entirely normal for them, not a sign of kidney problems. However, genuinely excessive elevation may indicate kidney stress from dehydration, certain supplements, or high-protein diets combined with inadequate hydration. Context matters—your creatinine should be interpreted alongside your muscle mass and supplement use. Results outside the normal range may need a follow-up with your GP.

eGFR estimates how well your kidneys are filtering blood, calculated from your creatinine level, age, sex, and ethnicity. It's the standard measure of kidney function used clinically. Normal eGFR is above 90 mL/min. Because eGFR is calculated from creatinine, muscular athletes may have a falsely low eGFR due to their higher creatinine from increased muscle mass—this doesn't necessarily indicate kidney problems. However, genuinely reduced eGFR is a concern because kidney disease often has no symptoms until advanced. Monitoring eGFR is important for athletes using supplements or medications that may stress the kidneys, those with very high protein intakes, and anyone wanting to ensure their training regimen isn't causing harm. Results outside the normal range may need a follow-up with your GP.

Total cholesterol measures all cholesterol in your blood, combining both protective HDL and potentially harmful LDL types. Despite its bad reputation, cholesterol is essential—it's the building block for steroid hormones including testosterone, forms cell membranes, and is needed for vitamin D synthesis. Athletes need adequate cholesterol for optimal hormone production. Very low cholesterol can actually impair testosterone synthesis. However, excessive LDL cholesterol increases cardiovascular risk. The detailed breakdown in this panel (HDL, LDL, ratio) provides much more useful information than total cholesterol alone. Regular exercise typically improves cholesterol profile by raising protective HDL. Results outside the normal range may need a follow-up with your GP.

LDL (low-density lipoprotein) cholesterol transports cholesterol to tissues throughout your body. While essential for cell function and hormone production, excessively high LDL can accumulate inside artery walls, forming plaques that narrow and stiffen arteries (atherosclerosis). This process increases cardiovascular disease risk. Regular aerobic exercise and a healthy diet typically help maintain optimal LDL levels. Athletes can have elevated LDL from very high-calorie diets, excessive saturated fat intake, or genetic factors. Optimal LDL is below 3 mmol/L for most people, with lower targets for those at higher cardiovascular risk. Results outside the normal range may need a follow-up with your GP.

Non-HDL cholesterol is calculated by subtracting protective HDL from total cholesterol. It includes all potentially harmful cholesterol fractions—not just LDL, but also VLDL and other atherogenic lipoproteins. This makes non-HDL a more comprehensive cardiovascular risk marker than LDL alone because it captures all the cholesterol that can contribute to artery plaque formation. The target for non-HDL cholesterol is below 4 mmol/L for most adults. Non-HDL is particularly useful because it doesn't require fasting to measure accurately. Results outside the normal range may need a follow-up with your GP.

HDL (high-density lipoprotein) cholesterol is 'good' cholesterol—it removes excess cholesterol from tissues and artery walls, transporting it back to the liver for disposal. Higher HDL levels are associated with lower cardiovascular risk. Regular aerobic exercise is one of the most effective ways to raise HDL levels, so athletes often have higher HDL than sedentary individuals. Moderate alcohol consumption and healthy fats (olive oil, nuts, oily fish) also raise HDL. HDL levels above 1.0 mmol/L in men and 1.2 mmol/L in women are generally considered desirable—the higher the better. Low HDL is an independent cardiovascular risk factor. Results outside the normal range may need a follow-up with your GP.

The total cholesterol to HDL ratio indicates what proportion of your total cholesterol is the protective HDL type. A lower ratio is better—it means more of your cholesterol is the protective variety. This ratio is used in cardiovascular risk calculators and provides more useful information than total cholesterol alone. A ratio below 4 is generally considered optimal; above 6 indicates increased cardiovascular risk. Regular aerobic exercise typically improves this ratio by raising HDL. Athletes who track this marker over time can see how their training and nutrition are affecting their cardiovascular health. Results outside the normal range may need a follow-up with your GP.

Triglycerides are fats that circulate in your blood and provide energy for your muscles during exercise. After eating, your body converts excess calories—whether from fat, carbohydrates, or protein—into triglycerides for storage. Between meals, triglycerides are released from fat stores for energy. Elevated fasting triglycerides may indicate excessive calorie intake, poor carbohydrate metabolism, inadequate recovery between training sessions, or excessive alcohol consumption. Very high triglycerides increase cardiovascular risk. Regular exercise and avoiding excessive refined carbohydrates typically help maintain healthy triglyceride levels. Fasting triglycerides below 1.7 mmol/L are generally desirable. Results outside the normal range may need a follow-up with your GP.

HbA1c measures the percentage of haemoglobin with glucose attached, reflecting your average blood sugar control over the past 2-3 months. Unlike a fasting glucose test, HbA1c isn't affected by what you ate yesterday—it shows the bigger picture. For athletes and active individuals, good glucose control is important for optimal performance, recovery, and body composition. Poor glucose control impairs recovery, reduces endurance capacity, promotes inflammation, and makes it harder to build muscle while losing fat. An HbA1c below 42 mmol/mol is normal; 42-47 indicates prediabetes (increased risk); 48 or above suggests diabetes. Regular exercise improves insulin sensitivity and typically helps maintain healthy HbA1c levels. Results outside the normal range may need a follow-up with your GP.

Folate (vitamin B9) is essential for red blood cell production, DNA synthesis, cell division, and protein metabolism. For athletes, folate supports the increased red blood cell production needed for optimal oxygen delivery to muscles, and aids recovery from training. Low folate can cause macrocytic anaemia (large, inefficient red blood cells), fatigue, weakness, and impaired recovery. Athletes with high training volumes have increased folate requirements. Folate is found in green leafy vegetables, legumes, fortified cereals, and some fruits. Serum folate reflects recent dietary intake over days to weeks. Results outside the normal range may need a follow-up with your GP.

Active B12 (holotranscobalamin) measures the portion of vitamin B12 actually available to your cells—more accurate than total B12. B12 is crucial for red blood cell production, nerve function, energy metabolism, and DNA synthesis. For athletes, B12 deficiency causes fatigue, weakness, reduced endurance capacity, and impaired recovery. Neurological symptoms (numbness, tingling, balance problems) can develop if deficiency is prolonged. B12 is found almost exclusively in animal products, so vegetarian and vegan athletes are at high risk of deficiency without supplementation. B12 absorption decreases with age and with certain medications (metformin, proton pump inhibitors). Stop B12 supplements 2 weeks before testing for accurate baseline assessment. Results outside the normal range may need a follow-up with your GP.

Vitamin D is essential for bone health, muscle function, immune system performance, and testosterone production. For athletes, vitamin D deficiency impairs muscle strength and power, increases injury risk (particularly stress fractures), compromises recovery, suppresses immune function, and may reduce testosterone levels. Vitamin D deficiency is extremely common in the UK due to limited sun exposure, and athletes who train indoors are at particular risk. Levels above 50 nmol/L are generally considered adequate; many sports medicine practitioners recommend levels above 75 nmol/L for optimal athletic performance. Most people in the UK benefit from supplementation, particularly in winter months (October-March) when UV exposure is insufficient for skin synthesis. Results outside the normal range may need a follow-up with your GP.

High-sensitivity CRP measures low-level inflammation in your body. CRP is produced by the liver in response to inflammation anywhere in the body—the 'high-sensitivity' test detects the subtle elevations relevant to chronic inflammation rather than just acute illness. In the context of fitness and training, chronically elevated hs-CRP can indicate inadequate recovery, overtraining syndrome, underlying injury, or excessive training volume. Inflammation impairs recovery, increases injury risk, and can compromise performance. Acute elevation immediately after intense training is normal and temporary—this is why resting for 48 hours before testing is important to see your baseline rather than acute training effects. Elevated hs-CRP is also an independent cardiovascular risk factor. If you have an acute illness when you test, your CRP will be elevated due to the illness rather than training-related factors. Results outside the normal range may need a follow-up with your GP.

DHEA sulphate (DHEAS) is a hormone produced by your adrenal glands that serves as a precursor to both testosterone and oestrogen. It plays important roles in muscle building, energy production, immune function, and overall vitality. DHEAS levels naturally peak in your 20s and gradually decline from around age 30 onwards—by age 70-80, levels may be only 10-20% of peak values. In the context of fitness and athletic performance, adequate DHEAS supports anabolic (muscle-building) processes and may contribute to training adaptation and recovery. Low DHEAS can contribute to fatigue, reduced training capacity, poor recovery, and difficulty building muscle. However, DHEAS is just one piece of the hormonal puzzle and is best interpreted alongside testosterone and cortisol. Results outside the normal range may need a follow-up with your GP.

Cortisol is your body's primary stress hormone, produced by the adrenal glands in response to physical stress (including exercise), psychological stress, illness, and injury. It's essential for survival—regulating blood pressure, blood sugar, immune function, and the inflammatory response. Cortisol follows a strong circadian rhythm, peaking in the morning and declining through the day, which is why morning testing is important for accurate results. In the context of training, cortisol is catabolic—it promotes the breakdown of protein and can oppose the anabolic effects of testosterone. Acute elevation after intense exercise is normal and part of the adaptation process. However, chronically elevated cortisol from overtraining, inadequate recovery, poor sleep, or excessive life stress impairs muscle building, suppresses immune function, promotes fat storage, and indicates the body is under excessive stress. The testosterone:cortisol ratio provides insight into whether your training load is appropriate. Results outside the normal range may need a follow-up with your GP.