Blood Test Glossary — A to Z
Plain English glossary of every common blood test marker, acronym and abbreviation used in Australian pathology — with units, reference ranges and what each measures.
How to Use This Glossary
Australian pathology reports use around 80 commonly seen abbreviations. This page covers the ones you are most likely to see, organised alphabetically. Each entry includes the full name, units, typical adult reference range and a plain-English description of what the marker measures.
Use it as a reference next to your pathology PDF. Most reports list the abbreviation in the leftmost column, the value in the next column, then the reference range and a flag (H, L, * or arrow) if the value is outside range.
How Australian Pathology Reports Are Structured
A standard Australian pathology report has four columns: test name (or abbreviation), your value, units, and reference range. A fifth column or a flag character (H, L, *, or arrow) indicates whether your value is outside range.
Reference ranges are typically derived from 95 percent of a healthy reference population. By definition, around 5 percent of healthy people sit outside the range — so a single mildly out-of-range value does not always indicate disease. Context, comparison with previous results, and your symptoms all matter.
A to E
ALT
Liver cell enzyme. Rises when liver cells are damaged — alcohol, fatty liver, hepatitis, medications.
AST
Liver and muscle enzyme. Less liver-specific than ALT but very useful in combination.
ALP
Bile duct and bone enzyme. Rises with bile flow obstruction, bone disease and during growth in children.
Albumin
Main blood protein made by the liver. Low in liver disease, malnutrition, kidney protein loss and acute illness.
ANA
Screening antibody for autoimmune disease (lupus, scleroderma, mixed connective tissue disease). Positive in around 10 percent of healthy adults too.
Anion gap
Calculated value (sodium minus chloride minus bicarbonate). High in metabolic acidosis (DKA, lactic acidosis, poisoning).
APTT
Tests the intrinsic clotting pathway. Used to monitor heparin therapy and investigate bleeding disorders.
B12
Essential for red cell production and nerve function. Deficiency from vegan diet, malabsorption, metformin, PPI use.
Basophils
Rarest white cell type. High in chronic myeloid leukaemia, allergy and parasitic infection.
Bilirubin
Breakdown product of haemoglobin. High in liver disease, bile duct obstruction, haemolysis, Gilbert syndrome (benign cause of mild high bilirubin).
BUN / Urea
Australian labs report Urea (mmol/L); US labs report BUN (mg/dL). High in dehydration, kidney disease, high-protein diet, gut bleeding.
Ca / Calcium
Strict regulation. High in hyperparathyroidism, cancer, vitamin D excess. Low in hypoparathyroidism, vitamin D deficiency, magnesium deficiency.
CK
Muscle enzyme. High after intense exercise, statin myopathy, rhabdomyolysis, heart attack.
Cl / Chloride
Main negative electrolyte. Usually moves with sodium. Abnormal in acid-base disorders and prolonged vomiting.
Cortisol
Adrenal stress hormone. Best taken fasted at 8am. Low in Addison disease and adrenal suppression. High in Cushing syndrome and acute stress.
Creatinine
Muscle breakdown product cleared by kidneys. Used to calculate eGFR. Higher in muscular adults; lower in frail older adults.
CRP
Acute inflammation marker. Rises within hours of infection or injury. Above 100 suggests bacterial infection.
D-dimer
Clot breakdown product. Used to rule out deep vein thrombosis and pulmonary embolism — negative result reliably excludes them in low-risk patients.
eGFR
Calculated kidney function from creatinine and age. Below 60 for 3 months defines chronic kidney disease. Below 30 is severe.
Eosinophils
Allergy and parasite-related white cell. High in asthma, eczema, drug reaction, worm infection.
ESR
Slower inflammation marker than CRP. Less specific but useful in chronic inflammatory conditions and temporal arteritis.
F to J
Ferritin
Iron storage protein. Below 30 = depleted iron stores; below 15 = iron deficiency. Also an acute phase reactant, so can be falsely high during inflammation.
FBE / FBC
The most common blood test. Counts RBCs, WBCs and platelets plus calculates haemoglobin, MCV, MCH, MCHC and RDW.
Folate
B vitamin essential for red cell production. Low in poor diet, alcoholism, methotrexate, malabsorption.
Free T3 (FT3)
Active form of thyroid hormone. Useful when TSH is abnormal but free T4 is normal, or to confirm hyperthyroidism.
Free T4 (FT4)
Main thyroid hormone (later converted to T3). Low in hypothyroidism, high in hyperthyroidism.
Fasting glucose
Single fasting blood sugar value. Together with HbA1c, the foundation of diabetes diagnosis.
GGT
Sensitive marker of bile duct disease and recent alcohol use. Often disproportionately high in alcohol-related liver disease.
Globulins
Total protein minus albumin. High in chronic infection, autoimmune disease, multiple myeloma.
Haematocrit / Hct / PCV
Proportion of blood that is red cells. High in polycythaemia, dehydration. Low in anaemia.
Haemoglobin / Hb
Oxygen-carrying protein in red cells. Below range = anaemia. Above = polycythaemia.
HbA1c
Three-month average glucose. 5.7-6.4 percent = prediabetes; 6.5 percent or above = diabetes. The single most important diabetes marker.
HDL
Beneficial cholesterol. Higher is generally better. Low HDL is part of metabolic syndrome.
hs-CRP
A more sensitive CRP assay. Used for cardiovascular risk stratification.
IgA / IgG / IgM
Antibody classes. Low in immune deficiency; high in chronic infection, autoimmune disease, multiple myeloma.
K to O
K+ / Potassium
Key intracellular electrolyte. Critical for heart and muscle function. Above 6.5 is a medical emergency.
LDH
Tissue damage marker. High in haemolysis, muscle injury, liver disease, lymphoma, some cancers.
LDL
Atherogenic cholesterol. Higher LDL means higher cardiovascular risk. Target depends on individual risk.
Lipase
Pancreatic enzyme. Markedly elevated (above 3x normal) in acute pancreatitis. More specific than amylase.
Lymphocytes
B and T white blood cells. High in viral infection (e.g. mononucleosis, COVID), chronic lymphocytic leukaemia. Low in HIV, immunosuppression, chemotherapy.
Magnesium
Important for muscle, nerve and cardiac function. Low in diuretic use, chronic alcohol use, malabsorption. Causes cramps, palpitations.
MCH
Average haemoglobin content per red cell. Low in iron deficiency.
MCHC
Haemoglobin concentration in red cells. Used with MCV to classify anaemia type.
MCV
Average red cell size. Low = microcytic (iron deficiency, thalassaemia). High = macrocytic (B12, folate, alcohol, hypothyroidism).
Monocytes
Tissue-resident immune cells. High in chronic infection, autoimmune disease, some leukaemias.
Neutrophils
Most abundant white cell. High in bacterial infection, inflammation, stress. Low (neutropenia) in chemo, viral illness, some drugs.
Non-HDL
Total cholesterol minus HDL. Includes all atherogenic particles. Better risk marker than LDL alone, especially when triglycerides are high.
PSA
Prostate marker. Used for prostate cancer screening in men over 50 (or earlier with family history). Affected by BPH, prostatitis, recent ejaculation.
P to T
Phosphate
Closely linked with calcium and vitamin D. Abnormal in kidney disease, parathyroid disorders, refeeding syndrome.
Platelets
Clotting cells. Low (thrombocytopenia) in viral illness, autoimmune ITP, leukaemia. High (thrombocytosis) in chronic inflammation, post-splenectomy, essential thrombocythaemia.
Prolactin
Pituitary hormone. High in pituitary tumours (prolactinoma), some medications, hypothyroidism, pregnancy.
PT/INR
Tests extrinsic clotting pathway. INR is the standardised form used to monitor warfarin therapy. Target INR depends on indication.
RBC
Total red cell number per litre. Combined with MCV and Hb, classifies anaemia type.
RDW
Variation in red cell size. High in early or mixed iron / B12 / folate deficiency. Can be the first clue to iron deficiency before MCV falls.
Reticulocytes
Young red cells. High after blood loss, haemolysis or iron replacement (showing the marrow responding). Low in marrow failure or untreated anaemia.
SHBG
Binds testosterone and oestradiol. Affects bioavailability — high SHBG reduces free hormone, low SHBG increases it.
Sodium
Main extracellular electrolyte. Abnormalities reflect water balance more than salt intake. Below 125 or above 155 is dangerous.
T3
Total active thyroid hormone (free T3 is the more clinically useful measure).
T4
Total thyroxine. Free T4 is preferred for clinical decisions.
TC
Sum of LDL plus HDL plus other particles. Less useful alone than the full lipid panel.
Testosterone
Main male androgen. Low in primary hypogonadism, ageing, opioids, obesity. Best measured fasted at 8am.
TIBC
Capacity of transferrin to bind iron. High in iron deficiency. Low in inflammation, chronic disease.
Total Protein
Albumin plus globulins. Useful for screening but the individual fractions matter more.
Transferrin
Iron transport protein. Counterpart to TIBC.
Transferrin saturation
Iron divided by TIBC. Below 15 percent = iron deficiency. Above 45 percent = iron overload (haemochromatosis).
Triglycerides
Blood fat reflecting recent dietary intake and metabolic state. High in metabolic syndrome, alcohol, diabetes, hypothyroidism.
Troponin
Heart muscle damage marker. Rises within hours of myocardial infarction. Critical for diagnosing heart attack.
TSH
Pituitary hormone driving thyroid function. The most sensitive single thyroid test. High = underactive thyroid; low = overactive.
U to Z
Urate / Uric acid
Breakdown product of purines. High in gout, kidney disease, diuretic use. Aim to keep below 0.36 if you have a history of gout.
Urea
Protein breakdown product cleared by kidneys. High in dehydration, high-protein diet, kidney disease, gut bleeding. Australian equivalent of US BUN.
Vitamin D (25-OH)
Storage form of vitamin D. Below 50 is the Australian Medicare threshold for deficiency. Supplementation typically 1000-2000 IU daily.
WBC / WCC
Total white cell count. Differential breakdown into neutrophils, lymphocytes, monocytes, eosinophils, basophils tells you the cause of abnormalities.
Zinc
Essential trace mineral. Deficiency causes hair loss, poor wound healing, taste changes. Rarely measured in standard panels but useful in suspected deficiency.
Australian Units — Quick Reference
Australia uses SI units (mmol/L, umol/L, g/L). The US still uses mass-based units (mg/dL, g/dL). If you are comparing AU results to US references, you may need to convert.
Glucose
mmol/L x 18 = mg/dL (so 5 mmol/L = 90 mg/dL)
Cholesterol (total, LDL, HDL)
mmol/L x 38.67 = mg/dL (so 5 mmol/L = 193 mg/dL)
Triglycerides
mmol/L x 88.57 = mg/dL (so 1 mmol/L = 89 mg/dL)
Urea (BUN)
mmol/L x 2.8 = mg/dL (so 5 mmol/L urea = 14 mg/dL BUN)
Creatinine
umol/L / 88.4 = mg/dL (so 88 umol/L = 1.0 mg/dL)
Bilirubin
umol/L / 17 = mg/dL (so 17 umol/L = 1.0 mg/dL)
Haemoglobin
g/L / 10 = g/dL (so 150 g/L = 15 g/dL)
HbA1c
Same units (percent or mmol/mol IFCC). Both used in Australia.
Common Australian Pathology Acronyms
Panel names and process acronyms you will see on Australian request forms and reports.
FBE
Full Blood ExaminationAustralian term for FBC (Full Blood Count). The basic blood panel.
U&E / EUC
Urea & Electrolytes / Electrolytes, Urea, CreatinineBasic biochemistry panel: sodium, potassium, chloride, bicarbonate, urea, creatinine, eGFR.
LFT
Liver Function TestsALT, AST, ALP, GGT, bilirubin, total protein, albumin.
TFT
Thyroid Function TestsUsually TSH plus free T4. May include free T3 and antibodies.
BSL
Blood Sugar LevelCasual or fasting glucose measurement.
OGTT
Oral Glucose Tolerance TestTwo-hour test with 75g glucose drink, used for gestational and complex diabetes diagnosis.
ELISA
Enzyme-Linked Immunosorbent AssayCommon antibody / antigen testing technique (e.g. HIV, hepatitis, coeliac antibodies).
POCT
Point-of-Care TestingBedside or in-office testing (e.g. finger-prick HbA1c, INR). Less precise than full lab assay.
RCV
Reference Change ValueThe smallest difference between two results that represents real change (not lab variation).
NATA
National Association of Testing AuthoritiesAustralian accreditation for pathology labs. All AU pathology labs are NATA-accredited.
RCPA
Royal College of Pathologists of AustralasiaSets pathology standards and runs the Quality Assurance Program for AU labs.
Decoding Your Lab Report Format
Value column
The number measured for you. Compare against the reference column. Single-decimal precision is the norm for most markers; some (HbA1c, lipids) use two decimals.
Units column
Always check the units. A creatinine of 88 in umol/L is normal; the same number in mg/dL would be impossible. Australian labs use SI (mmol/L, umol/L, g/L) almost exclusively.
Reference range column
Shows the lab's adult reference range. Some labs split by sex (M / F) and age. A value outside this range is flagged. Reference ranges derive from 95 percent of a healthy population, so 5 percent of healthy people will sit just outside the range.
Flag column
H or up arrow = above range. L or down arrow = below range. HH/LL or double arrow or red asterisk = critically far from range, requires urgent action. Different Australian labs use different conventions.
Footer notes
Lab reports often include a footer with comments — haemolysis noted, lipaemia interfering with results, calculated values, method changes. Read them; they affect interpretation.
Markers That Need Immediate Action If Outside Range
Some results warrant urgent attention regardless of how you feel. Critical values triggering same-day GP or ED contact.
Troponin elevated above 14 ng/L
Suggests acute heart muscle injury / myocardial infarction. ED immediately if symptoms (chest pain, breathlessness, dizziness, sweating).
Potassium above 6.5 mmol/L
Life-threatening cardiac arrhythmia risk. Same-day medical review. ECG immediately. Cause is usually kidney impairment or medications (ACE inhibitors, spironolactone).
Sodium below 125 mmol/L
Severe hyponatraemia. Can cause confusion, seizures and brain swelling. Cause is usually fluid overload, diuretics, SIADH or ecstasy use.
Glucose below 3 or above 25 mmol/L
Below 3 = severe hypoglycaemia (eat fast carb immediately, call ambulance if confused). Above 25 = severe hyperglycaemia, check ketones, ED if DKA symptoms (vomiting, abdominal pain, deep breathing).
INR above 4 (not on warfarin) or above target on warfarin
Major bleeding risk. Same-day medical contact. Avoid trauma. Vitamin K may be needed.
Neutrophils below 0.5 x10^9/L
Severe neutropenia. Life-threatening infection risk. Avoid crowds, raw food. Any fever needs same-day ED. Cause is usually chemotherapy or certain drugs.
Haemoglobin below 70 g/L
Severe anaemia. Symptomatic shortness of breath and dizziness are likely. Same-day medical review. Transfusion may be needed.
Platelets below 20 x10^9/L
Severe thrombocytopenia. Spontaneous bleeding risk. Avoid trauma and NSAIDs. Same-day haematology review.
Related Reading
Auto-Recognises Every Marker in This Glossary
SmarterBlood reads any Australian pathology PDF and recognises all 491 markers we have in our master database — including abbreviations, alternative names and both SI and US units. No more Googling acronyms.
Reference ranges shown are typical Australian adult ranges. Different pathology labs use slightly different ranges, and ranges differ for children, during pregnancy, and in certain medical conditions. Always check your own pathology report's reference column. This page provides general educational information only and is not a substitute for medical advice. SmarterBlood does not provide medical care.