Haematology
Haemoglobin
Haemoglobin is the iron-containing protein in red blood cells that carries oxygen from the lungs to the tissues and returns carbon dioxide for exhalation. Its concentration in whole blood is the primary screen for anaemia and a core measure for monitoring blood loss, transfusion need and treatment response.
Why it is measured
Haemoglobin is one of the most frequently requested tests in medicine, underpinning decisions on anaemia, transfusion thresholds and chronic disease monitoring. Point-of-care measurement delivers a result in seconds from a small fingerprick or whole-blood sample, supporting rapid triage in clinics, blood donation centres and emergency settings.
| Typical range | Indicative adult range: men approximately 130 to 170 g/L (13.0 to 17.0 g/dL); non-pregnant women approximately 120 to 155 g/L (12.0 to 15.5 g/dL). WHO anaemia thresholds sit at about 130 g/L for men and 120 g/L for non-pregnant women. Ranges vary by method, analyser, altitude and pregnancy status. SI units are g/L, while many devices report g/dL (1 g/dL = 10 g/L); always check the units and reference range issued with the result. |
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| Sample | Capillary (fingerprick) or venous whole blood; blood gas platforms also accept arterial whole blood. Non-invasive transcutaneous measurement of total haemoglobin (SpHb) is available on certain spot-check monitors. No anticoagulant or fasting preparation is required for dedicated photometer microcuvettes. |
| Turnaround | Typically under 1 minute. Dedicated haemoglobin photometers and blood gas analysers report within roughly 10 to 60 seconds, and non-invasive spot-check monitors give a near-instant reading. |
Point of care devices that report it
- HemoCue Hb 201+ (dedicated haemoglobin photometer)
- HemoCue Hb 801 (dedicated haemoglobin photometer)
- Abbott i-STAT (handheld blood analyser, reports haemoglobin and haematocrit)
- Siemens Healthineers epoc Blood Analysis System
- Radiometer ABL90 FLEX (blood gas analyser, reports total haemoglobin)
- Masimo Pronto with SpHb (non-invasive total haemoglobin spot-check)
Questions, answered
Why can a point-of-care haemoglobin result differ from the main laboratory value?
Differences usually reflect sample type and method. Capillary fingerprick blood can read slightly differently from venous blood, poor sampling technique (such as excessive squeezing or the first drop not being wiped) can dilute or alter the reading, and POCT photometry differs from automated impedance counters in the laboratory. A small bias is expected; if a result is clinically important or unexpectedly low or high, it is good practice to confirm with a laboratory venous sample.
Does point-of-care haemoglobin testing need quality control?
Yes. Operators should run the manufacturer's quality control material at the intervals stated in the device instructions, log results, check calibration and lot numbers, and participate in an external quality assessment (EQA) scheme where available. Documented QC and operator training are expected under POCT governance frameworks such as ISO 15189 and ISO 22870.
Is non-invasive (SpHb) haemoglobin as reliable as a blood sample?
Non-invasive total haemoglobin monitors are useful for screening and for trending changes over time without a needle, but they are generally less precise than a whole-blood measurement and can be affected by perfusion, motion and pigmentation. A low or borderline non-invasive reading is normally confirmed with an invasive sample before acting on it.