Globulin
Globulin refers to a broad group of proteins in the blood, including immunoglobulins (antibodies), transport proteins, and enzymes. These proteins are essential for immune function, hormone transport, and inflammatory response. The balance of globulins plays a crucial role in the body’s defence mechanisms and nutritional status. Elevated globulin levels may suggest chronic infections, autoimmune conditions, liver disease, or certain blood disorders such as multiple myeloma. Low levels, on the other hand, can point to protein-losing conditions, liver dysfunction, or immune deficiency. As part of a total protein profile, globulin helps provide a clearer picture of immune health and systemic inflammation.
Total Protein
Total Protein measures the overall concentration of proteins in the plasma, primarily albumin and globulin. This marker reflects both liver synthetic function and overall nutritional health. Decreased total protein levels may result from malnutrition, liver disease, nephrotic syndrome, or gastrointestinal losses. Elevated levels are often seen in chronic inflammation, certain infections, and plasma cell disorders. Monitoring total protein can offer early clues to metabolic imbalance, poor dietary intake, or chronic disease activity.
Gamma-Glutamyltransferase (GGT)
GGT is an enzyme located predominantly in the liver and bile ducts. It plays a role in glutathione metabolism and cellular detoxification. Elevated GGT levels are a sensitive indicator of liver dysfunction and can signal bile duct obstruction, alcoholic liver disease, or hepatotoxic medication use. In the absence of other abnormal liver enzymes, isolated GGT elevation may still warrant investigation, particularly in individuals with alcohol use or metabolic syndrome. GGT is also used to confirm liver origin in cases where alkaline phosphatase is elevated.
Alkaline Phosphatase (ALP)
ALP is an enzyme found in the liver, bones, bile ducts, and intestinal lining. It is involved in bone turnover and bile flow. Elevated ALP levels may indicate liver or bile duct obstruction, bone diseases such as Paget’s disease or osteomalacia, or healing fractures. In younger individuals, mild elevations can be physiological due to bone growth. Low ALP may suggest hypothyroidism or malnutrition. In conjunction with GGT and liver function tests, ALP helps differentiate between hepatic and skeletal pathology.
Triglycerides
Triglycerides are the most common form of fat in the body and are stored for energy. Elevated triglyceride levels are associated with insulin resistance, obesity, type 2 diabetes, and an increased risk of cardiovascular events. Extremely high levels may lead to pancreatitis. In clinical practice, fasting triglyceride levels are often evaluated alongside HDL and LDL cholesterol to assess the presence of metabolic syndrome and cardiovascular risk.
HDL (High-Density Lipoprotein) Cholesterol
HDL cholesterol is known as "good" cholesterol because it removes excess cholesterol from the bloodstream and transports it to the liver for excretion. High HDL levels are protective against atherosclerosis and cardiovascular disease. Low HDL, particularly when combined with high triglycerides or LDL cholesterol, increases the risk of heart disease. Improving HDL often involves lifestyle changes such as exercise, weight management, and smoking cessation.
HDL % (HDL as a Percentage of Total Cholesterol)
This metric reflects the proportion of HDL in relation to total cholesterol. A higher percentage indicates a healthier lipid profile and reduced cardiovascular risk. It provides a more refined assessment of lipid balance than absolute values alone and is useful for identifying atherogenic dyslipidaemia in borderline cases.
Non-HDL Cholesterol
Non-HDL cholesterol is calculated by subtracting HDL from total cholesterol. It includes all potentially atherogenic lipoproteins, such as LDL, VLDL, and intermediate-density lipoprotein (IDL). This marker is especially valuable in predicting cardiovascular risk in individuals with high triglycerides or metabolic syndrome, as it provides a more complete picture of total “bad” cholesterol load.
Total Cholesterol
Total cholesterol is the sum of HDL, LDL, and other lipid fractions. While it offers a broad measure of lipid status, its interpretation is more meaningful when analysed alongside HDL, LDL, and triglycerides. Persistently elevated total cholesterol is associated with increased risk of cardiovascular disease and should be monitored as part of a comprehensive lipid profile.
LDL (Low-Density Lipoprotein) Cholesterol
LDL is often referred to as “bad” cholesterol because it contributes to plaque buildup in arteries (atherosclerosis). Elevated LDL levels increase the risk of coronary artery disease, stroke, and peripheral vascular disease. Lowering LDL through dietary change, exercise, or medication (such as statins) is a primary focus of cardiovascular prevention strategies endorsed by NICE and the British Heart Foundation.
Free Thyroxine (FT4)
FT4 is the unbound, biologically active form of thyroxine produced by the thyroid gland. It regulates metabolism, energy production, and thermoregulation. Abnormal FT4 levels may indicate thyroid dysfunction—low levels in hypothyroidism and high levels in hyperthyroidism. FT4 is commonly measured alongside TSH to assess thyroid status and guide treatment decisions.
Free Triiodothyronine (FT3)
FT3 is the active thyroid hormone that exerts metabolic effects at the cellular level. It is derived from the conversion of FT4 and plays a key role in regulating heart rate, body temperature, and energy expenditure. FT3 is particularly useful in diagnosing early or subclinical hyperthyroidism when TSH is suppressed but FT4 is normal.
Thyroid Stimulating Hormone (TSH)
TSH is secreted by the pituitary gland to stimulate the thyroid to produce FT4 and FT3. It serves as the most sensitive marker of thyroid function. Elevated TSH suggests hypothyroidism, whereas suppressed TSH indicates hyperthyroidism. TSH testing is the starting point for most thyroid evaluations and is crucial in monitoring treatment response.
Urea
Urea is a by-product of protein metabolism, generated in the liver and excreted by the kidneys. Its concentration reflects kidney function, hydration status, and protein intake. Elevated urea may indicate impaired renal clearance, high-protein diet, or dehydration. Low levels can occur in liver disease or severe malnutrition.
Creatinine
Creatinine is a waste product from muscle breakdown and is cleared almost entirely by the kidneys. It is a core marker for assessing kidney function. Elevated creatinine suggests reduced glomerular filtration, which may signal acute or chronic kidney impairment. Creatinine is used in the calculation of eGFR to provide a more complete picture of renal health.
Estimated Glomerular Filtration Rate (eGFR)
eGFR is a calculated estimate of kidney function based on serum creatinine, age, sex, and body size. It reflects how efficiently the kidneys filter waste from the blood. A declining eGFR indicates deteriorating kidney function and is a key metric in diagnosing and staging chronic kidney disease (CKD).
Iron
Iron is vital for producing haemoglobin, which transports oxygen in the blood. Iron deficiency can result in anaemia, fatigue, breathlessness, and impaired cognitive and physical performance. Elevated iron levels may suggest haemochromatosis or excessive supplementation. Iron status must be interpreted in conjunction with ferritin and transferrin saturation for accuracy.
Unsaturated Iron Binding Capacity (UIBC)
UIBC measures the blood’s capacity to bind additional iron. It reflects the amount of transferrin not yet saturated with iron. A high UIBC indicates low iron availability, often seen in deficiency. Low UIBC may suggest iron overload or reduced transferrin production.
Total Iron Binding Capacity (TIBC)
TIBC reflects the total amount of iron that can be carried by transferrin in the bloodstream. It is used alongside serum iron and UIBC to diagnose iron-related disorders. High TIBC is often associated with iron deficiency, while low values may indicate iron overload or chronic inflammation.
Transferrin Saturation
Transferrin Saturation is the percentage of transferrin that is actually carrying iron. It is a key functional marker of iron availability. Low transferrin saturation may indicate iron deficiency, while elevated values suggest iron overload, as seen in haemochromatosis or liver disease.
Ferritin
Ferritin is the primary iron storage protein in the body. It reflects the amount of stored iron in tissues. Low ferritin is a highly sensitive marker of iron deficiency, often detectable before anaemia develops. Elevated ferritin may indicate chronic inflammation, liver disease, or iron overload conditions.
Vitamin D (25-hydroxyvitamin D)
Vitamin D is essential for calcium absorption, immune regulation, and musculoskeletal health. Deficiency has been linked to osteoporosis, immune dysfunction, depression, and chronic fatigue. In the UK, deficiency is common, particularly in winter months. Supplementation is widely recommended by NICE when levels are suboptimal.
Testosterone
Testosterone is a key hormone involved in muscle growth, bone density, libido, energy, and mood regulation. In men, low testosterone may lead to fatigue, reduced strength, and low libido. In women, excess testosterone can cause irregular periods or hirsutism. Testosterone testing is valuable in assessing hormonal imbalances, particularly in the context of fatigue, infertility, or endocrine disorders.
Albumin
Albumin is the most abundant plasma protein, maintaining oncotic pressure and transporting hormones, fatty acids, and medications. Low albumin may result from liver disease, kidney dysfunction, or systemic inflammation. It is also a marker of nutritional status and chronic illness severity.
Alanine Aminotransferase (ALT)
ALT is an enzyme found primarily in the liver. It is released into the bloodstream when liver cells are damaged. Elevated ALT levels are commonly seen in viral hepatitis, fatty liver disease, and drug-induced liver injury. ALT is a sensitive and specific marker of liver cell injury.
Bilirubin
Bilirubin is a yellow pigment formed from the breakdown of red blood cells. It is processed by the liver and excreted in bile. Elevated bilirubin can cause jaundice and may signal liver dysfunction, haemolysis, or bile duct obstruction. It is often measured alongside liver enzymes in hepatic panels.
HbA1c (Glycated Haemoglobin)
HbA1c provides a long-term view of blood glucose control, reflecting average glucose levels over the past 8–12 weeks. It is the gold-standard test for diagnosing and monitoring type 2 diabetes. Elevated HbA1c is associated with increased risk of cardiovascular complications and organ damage.
Uric Acid
Uric acid is produced during the breakdown of purines found in food and the body’s cells. Elevated levels can lead to gout, a form of arthritis marked by painful joint inflammation, and may also contribute to kidney stones. Chronically high uric acid, or hyperuricaemia, may reflect poor renal clearance, dietary excess, or metabolic disturbances.
High-Sensitivity C-Reactive Protein (hs-CRP)
hs-CRP is a highly sensitive marker of low-grade systemic inflammation. Even slight elevations are associated with increased risk of cardiovascular events, insulin resistance, and chronic inflammatory diseases. hs-CRP is widely used in cardiovascular risk stratification and to monitor inflammatory status in both acute and chronic conditions.
