Lab tests
Arterial blood gas (ABG) report explainer
A blood gas result is usually a strip printed by an analyzer close to the bedside, full of chemical symbols, with some values measured and others worked out by the machine. Add your report below to see every symbol written out and each value shown beside the reference range printed with it.
Explain your arterial blood gas (ABG) report
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What you get
- Acid-base, oxygen and other lines grouped, each with your report's units.
- Symbols such as pCO2, HCO3-, BE, sO2 and FiO2 written out.
- Measured values told apart from the ones the analyzer calculates.
- Questions to ask the hospital team looking after you.
Lines you will usually see on a blood gas report
- pHA measure of the acidity of the blood
- pCO2 (or PaCO2)The pressure of carbon dioxide dissolved in the blood, in mmHg or kPa
- pO2 (or PaO2)The pressure of oxygen dissolved in the blood
- HCO3- (bicarbonate)A substance in the blood that buffers acid, usually calculated by the analyzer
- Base excess (BE)A calculated figure describing the balance of acid and base
- sO2 or SaO2The percentage of hemoglobin carrying oxygen
- LactateA substance produced when cells make energy, reported in mmol/L
What this tool cannot tell you
A blood gas is interpreted as a whole, together with how the person was breathing, how much oxygen they were receiving when the sample was taken and their existing conditions, and it is often repeated to follow a trend. Whether the sample was arterial, venous or capillary also changes which ranges apply. MedicDecode explains the symbols and shows what the printout marks as outside its own ranges. It does not name an acid-base pattern, say what caused it, or comment on oxygen or ventilator settings; the hospital team does that.
Common questions
What is the difference between pO2 and oxygen saturation?
pO2 is the pressure of oxygen dissolved in the blood, given in mmHg or kPa. Saturation (sO2) is the percentage of hemoglobin that is carrying oxygen. They are related, but they are separate lines with separate ranges.
What does FiO2 on the printout mean?
It is the fraction of oxygen in the air the person was breathing when the sample was taken, written as a decimal or a percentage. Staff record it because the oxygen results are read in the light of it. It is a setting noted on the report, not a blood result.
Why are my results in kPa when other reports use mmHg?
Both are units of pressure, and which one appears depends on the country and the hospital. The two scales give very different numbers, so a value can only be set against a range printed in the same unit. The explanation keeps the units on your report.
Words you may see on this report
Tap a word for its plain-English meaning, an example line and what it does not mean.
- ALT (Alanine Aminotransferase)
ALT is an enzyme found mainly in the liver; when liver cells are irritated or damaged, more ALT leaks into the blood.
- AST (Aspartate Aminotransferase)
AST is an enzyme found in the liver, muscles, heart and other tissues; raised levels can signal stress or damage in one of these.
- Bilirubin
Bilirubin is a yellow substance made when old red blood cells break down; the liver processes it so it can leave the body.
- Creatinine
Creatinine is a waste product from normal muscle activity that the kidneys filter out, so its blood level helps show how well the kidneys work.
- CRP (C-Reactive Protein)
CRP is a protein made by the liver that rises quickly when there is inflammation or infection in the body.
- Culture and Sensitivity
A culture and sensitivity test grows germs from a sample to identify them, then checks which antibiotics can stop them.
- eGFR (Estimated Glomerular Filtration Rate)
eGFR is an estimate of how well your kidneys filter waste from your blood, calculated from a creatinine blood test plus details like age.
- Electrolytes
Electrolytes are minerals in the blood, such as sodium, potassium and chloride, that carry an electric charge and help the body work.
- ESR (Erythrocyte Sedimentation Rate)
ESR measures how fast red blood cells sink in a tube of blood over an hour; a faster rate can be a general sign of inflammation.
- Fasting Sample
A fasting sample is blood taken after you have had nothing to eat or drink except water for a set number of hours.
- Ferritin
Ferritin is a protein that stores iron; its blood level gives a good idea of how much iron the body has in reserve.
- HbA1c
HbA1c shows your average blood sugar over roughly the past two to three months by measuring how much sugar is attached to red blood cells.