EUC stands for Urea, Electrolytes and Creatinine — sometimes also written as UEC or U+E. It is one of the most commonly ordered blood tests in Australia, included as part of nearly every routine GP health check. This guide explains exactly what an EUC blood test measures, what each result means, normal Australian reference ranges, and how to track your kidney function over time.
What does the EUC blood test measure?
An EUC panel typically includes seven values:
- Sodium (Na) — main extracellular electrolyte; controls fluid balance and nerve function.
- Potassium (K) — main intracellular electrolyte; critical for muscle and heart function.
- Chloride (Cl) — accompanies sodium; involved in acid-base balance.
- Bicarbonate (HCO₃) — buffer that regulates blood pH.
- Urea — waste product of protein metabolism, filtered by the kidneys.
- Creatinine — waste product of muscle metabolism, filtered by the kidneys.
- eGFR (estimated Glomerular Filtration Rate) — calculated estimate of how well your kidneys are filtering, derived from creatinine, age, sex.
Some Australian labs also report calcium, phosphate, magnesium, anion gap or albumin on the same panel — though these may also appear on a "biochemistry" or "general chemistry" panel depending on the lab.
Why is the EUC blood test ordered?
Australian GPs order EUC for many reasons:
- Routine health check — included in most adult annual checks, especially for people over 50, with hypertension, diabetes, or family history of kidney disease.
- Hypertension monitoring — high blood pressure damages kidneys over time, and many blood-pressure medications affect electrolytes.
- Diabetes monitoring — diabetic kidney disease is a leading cause of kidney failure in Australia.
- Medication safety — diuretics, ACE inhibitors, ARBs, lithium, NSAIDs, metformin and many other drugs require EUC monitoring.
- Symptoms of dehydration, vomiting, diarrhoea, severe sweating.
- Symptoms of kidney disease — fatigue, swelling (oedema), reduced urine output, foamy urine, nausea.
- Pre-operative assessment before surgery requiring anaesthesia.
- Hospital admission — EUC is part of the standard admission panel.
Normal EUC reference ranges in Australia
Reference ranges are RCPA-aligned and may vary slightly between labs. Typical Australian adult ranges:
| Marker | Reference range | What it tells you |
|---|---|---|
| Sodium | 135-145 mmol/L | Fluid balance, hydration |
| Potassium | 3.5-5.0 mmol/L | Muscle/heart function |
| Chloride | 96-110 mmol/L | Acid-base balance |
| Bicarbonate | 22-32 mmol/L | Acid-base buffer |
| Urea | 2.5-7.5 mmol/L | Protein metabolism, kidney clearance |
| Creatinine (men) | 60-110 µmol/L | Kidney filtration capacity |
| Creatinine (women) | 45-90 µmol/L | Kidney filtration capacity |
| eGFR | >60 mL/min/1.73m² normal · 30-59 reduced · <30 severely reduced | Overall kidney function |
What do abnormal EUC results mean?
High sodium (hypernatraemia, >145 mmol/L)
Most often dehydration — inadequate water intake, excessive sweating, diarrhoea, vomiting, or diabetes insipidus. Some medications (lithium, certain laxatives) and rare endocrine conditions (Conn''s syndrome, hyperaldosteronism) cause persistent hypernatraemia.
Low sodium (hyponatraemia, <135 mmol/L)
Common in older Australians. Causes include excessive water intake, certain medications (thiazide diuretics, SSRI antidepressants, carbamazepine), heart failure, liver cirrhosis, kidney disease, and SIADH (syndrome of inappropriate ADH secretion). Symptoms range from mild (lethargy, headache) to severe (seizures, coma) depending on rate of fall.
High potassium (hyperkalaemia, >5.0 mmol/L)
Most commonly caused by medications — ACE inhibitors, ARBs, potassium-sparing diuretics (spironolactone, amiloride), NSAIDs. Also kidney disease, Addison''s disease, severe muscle injury (rhabdomyolysis), and haemolysis (sample artefact). High potassium is dangerous because it can trigger cardiac arrhythmias.
Low potassium (hypokalaemia, <3.5 mmol/L)
Causes include vomiting, diarrhoea, diuretics (especially thiazides and loop diuretics), excessive licorice intake, hyperaldosteronism (Conn''s syndrome), and rare conditions like Bartter and Gitelman syndromes. Symptoms include muscle weakness, cramps, fatigue and arrhythmias.
High urea
Suggests reduced kidney clearance, dehydration, high protein intake, gastrointestinal bleeding (proteins from blood get reabsorbed and metabolised), or muscle breakdown. Often the first marker to rise in mild kidney impairment.
Low urea
Liver disease (impaired urea synthesis), low-protein diet, pregnancy, or overhydration. Rarely clinically significant in isolation.
High creatinine
Reduced kidney clearance, severe dehydration, recent intense exercise, large muscle mass, certain medications (trimethoprim, cimetidine block tubular secretion without true kidney damage). The eGFR adjusts for age and sex but cannot adjust for muscle mass — bodybuilders and athletes often have creatinine in the upper-normal or just-above range without kidney impairment.
Low creatinine
Low muscle mass (elderly, malnourished, prolonged illness), pregnancy, or sometimes liver disease. Rarely clinically significant.
Low eGFR
The most important EUC result for assessing kidney function. eGFR <60 for more than 3 months defines chronic kidney disease (CKD) under Australian KHA-CARI guidelines:
- eGFR >90: normal kidney function
- eGFR 60-89: mild reduction (CKD stage 2 if other evidence of kidney damage)
- eGFR 45-59: moderate reduction (CKD stage 3a)
- eGFR 30-44: moderately severe (CKD stage 3b)
- eGFR 15-29: severe (CKD stage 4)
- eGFR <15: kidney failure (CKD stage 5; usually requires dialysis or transplant)
Persistent eGFR below 60 should be confirmed with repeat testing 3 months later, plus urine albumin-to-creatinine ratio (uACR) to assess kidney damage.
Common patterns and what they mean
Pattern: high urea + high creatinine + low eGFR
Reduced kidney function. Could be acute (dehydration, recent NSAID use, contrast dye, sepsis) or chronic (diabetes, hypertension, polycystic kidney disease, glomerulonephritis). Repeat testing and uACR are the next steps.
Pattern: high urea + normal creatinine
Often dehydration or high protein intake. Sometimes early kidney impairment. Less commonly, gastrointestinal bleeding.
Pattern: low sodium + high potassium
Suggestive of Addison''s disease (adrenal insufficiency) — needs cortisol, ACTH and short Synacthen test to confirm. Also seen in severe kidney disease and certain medication combinations.
Pattern: low potassium + high bicarbonate
Metabolic alkalosis. Common causes include vomiting, diuretics, hyperaldosteronism, or excessive antacid use.
Preparing for an EUC blood test
- Hydration — drink water normally before the test. Severe dehydration can falsely elevate urea, creatinine and sodium.
- Avoid heavy exercise for 24-48 hours before — intense exercise raises creatinine and can transiently affect potassium.
- Avoid creatine supplements for several days before testing if your GP is investigating kidney function — creatine raises creatinine.
- Take medications as normal unless your GP specifies otherwise — many EUC panels are ordered specifically to check medication effects.
- Fasting is usually not required for EUC alone, but is often required if other tests (lipids, glucose) are on the same form.
How often should EUC be tested?
- Healthy adults: every 1-2 years as part of a routine health check.
- Hypertension or diabetes: every 6-12 months.
- Chronic kidney disease (eGFR <60): every 3-6 months, more frequently if rapidly declining.
- Starting or changing ACE inhibitors, ARBs, diuretics: 1-2 weeks after the change, then every 3-6 months.
- On lithium, NSAIDs, metformin or other nephrotoxic medications: as recommended by your GP, often 6-12 monthly.
Tracking EUC over time with BloodTrack
EUC is one of the markers where trends matter more than single values. A creatinine that has crept from 75 to 95 µmol/L over 5 years tells a different story than a one-off creatinine of 95. Same with eGFR drifting from 90 to 65 — that is the early signal of progressing kidney disease, well before any symptom.
BloodTrack lets you upload pathology PDFs from any major Australian lab (4Cyte, Laverty, SNP, ACL, Dorevitch, QML, DHM, Western Diagnostic) and instantly see your EUC trends over time, alongside every other marker. Free, in your browser, no download. Upload your pathology PDF.
For deeper context on each individual EUC marker, see our glossary: BloodTrack biomarker glossary.
Medical disclaimer: This article is for educational purposes only and is not medical advice. Always discuss your blood test results with a qualified healthcare professional.
