Lab tests explained
What 23 common tests measure, why they are done and how results are generally read. Reference ranges are quoted from Pathology Tests Explained, run by Australian pathology organisations.
Ranges differ between laboratories, and a result outside a range does not always mean something is wrong. Your doctor reads results with your history and symptoms.
Blood 2
Blood sugar 3
- Blood glucose (fasting) and glucose tolerance testMeasures the glucose in your blood at the time of the test. A fasting sample or a 2-hour glucose tolerance test can help diagnose diabetes.
- HbA1cShows what your blood glucose levels have been like over the past two to three months.
- Insulin and C-peptideMeasures insulin in the blood. It is most often used to investigate low blood glucose, usually together with C-peptide.
Gut 1
Heart 1
Hormones 4
- Cortisol testsMeasures cortisol in blood, urine or saliva. It is used to help diagnose Cushing's syndrome and Addison's disease, which are both rare.
- TestosteroneMeasures testosterone, the main male sex hormone, which females also have in smaller amounts.
- Thyroid antibodies (TPO)A blood test for antibodies against the thyroid, used when an autoimmune thyroid condition such as Hashimoto's disease is suspected.
- Thyroid function tests (TSH, free T4, free T3)Blood tests that show how well your thyroid is working. TSH is usually measured first, and free T4 and free T3 are added if TSH is abnormal.
Immune 2
Inflammation 2
Kidney 3
- Electrolytes (sodium, potassium, chloride, bicarbonate)Measures sodium, potassium, chloride and bicarbonate, salts that help regulate heart rhythm, nerves and muscles.
- Kidney function tests (creatinine and eGFR)Blood and urine tests that show how well your kidneys are clearing waste, including creatinine, eGFR, urea and the urine albumin to creatinine ratio (ACR).
- Uric acid (urate)Measures uric acid (urate), a waste product made when the body breaks down substances called purines. It helps diagnose gout.
Liver 1
Vitamins and minerals 4
- Homocysteine testMeasures homocysteine, an amino acid. It is most often used to assess vitamin B12, folate and B6 levels.
- Magnesium testMeasures magnesium in the blood, and sometimes the urine. Only about 1% of the body's magnesium is in the blood.
- Vitamin B12 and folate testsBlood tests for vitamin B12 and folate, usually ordered after a full blood count shows a problem, or for nerve symptoms.
- Vitamin D testMeasures 25-hydroxyvitamin D, the form of vitamin D made in the liver, which shows your overall vitamin D level.