From Sample Integrity to Analyser Confidence

Haemolysis, Icterus and Lipaemia (HIL)

 

Following a series of expert-led HIL sessions at ADLM 2026, we recap the key insights shared on haemolysis, icterus and lipaemia, exploring their impact on sample integrity, analyser performance and the importance of confidence in HIL detection.

 

Laboratories invest significant time and resources in quality control measures to ensure analytical systems are performing as expected. Yet before many clinical chemistry results are released, an equally important question needs to be considered:

 

 

Is the patient sample itself suitable for analysis?

 

Haemolysis, icterus and lipaemia (HIL) are among the most common and clinically significant sources of endogenous sample interference, with the potential to affect laboratory measurements and introduce clinically significant bias. Automated HIL checks provide an objective way of identifying potentially compromised samples before results are released.

 

 

But this raises another important question:

 

If laboratories rely on an analyser’s HIL index to determine whether a patient sample is acceptable, how can they be confident that the HIL detection system itself is performing correctly?

This is where Serum Indices Quality Control (QC) becomes important. Rather than simply generating another QC result, HIL QC challenges an analyser’s ability to recognise different levels of haemolysis, icterus and lipaemia, helping laboratories to have confidence in the decision that follows.

 

 

What are HIL indices?

 

HIL stands for:

• H – Haemolysis
• I – Icterus
• L – Lipaemia

 

Three important sources of interference that can affect serum and plasma samples used in clinical chemistry testing.

 

Modern automated analysers can assess patient samples for these characteristics and generate an HIL index, providing an objective assessment of sample integrity. Depending on the degree of interference and laboratory policy, this can help determine whether a result should proceed, trigger an interference alert or require further action.

 

 

Why does HIL matter?

 

HIL is not a single problem with a single cause. The condition of a sample can be influenced by the patient’s clinical condition as well as what happens during collection, handling, storage and transport.

 

Haemolysis occurs when red blood cells rupture and release intracellular components, including haemoglobin, into the surrounding serum or plasma. It can occur in vivo or during sample collection and handling. The scale of haemolysis highlighted at ADLM 2026 was significant, with some degree reported in 3.3% of routine samples received by central laboratories and an average of 30% in emergency department and trauma samples.

 

Icterus is associated with increased bilirubin within a sample and is predominantly linked to the patient’s underlying condition. Bilirubin can interfere with laboratory measurements, including certain enzymatic colorimetric reactions.

 

The potential impact extends across a range of laboratory tests, including iron, lipase, albumin, CK, ALT, AST, triglycerides, creatinine, uric acid, phosphate, potassium, LDH and cholesterol. The nature and magnitude of interference depend on the measurand, analytical method, instrument and degree of HIL present.

 

 

Who is checking the HIL check?

 

This is a key consideration for laboratories using automated HIL indices.

 

HIL indices can influence whether patient results are accepted, flagged or rejected. The analyser’s ability to detect and categorise HIL therefore needs to be monitored.

 

Routine instrument checks, such as blank calibration and optics checks, provide valuable information about analyser operation. However, dedicated HIL QC asks a different question:

 

Can the analyser correctly recognise different degrees of haemolysis, icterus and lipaemia?

 

Analyser performance can change over time due to factors including lamp ageing, optical path differences, algorithmic differences, reagent lot changes, calibration drift and maintenance inconsistencies. Even identical analyser models should therefore not automatically be assumed to perform identically.

 

For laboratories operating multiple analysers or sites, this can also make harmonisation an important consideration. HIL QC can help assess whether analysers are responding consistently to the same HIL challenge.

 

 

Why use a multi-level control?

 

HIL interference is not simply present or absent. Samples can contain different degrees of haemolysis, icterus and lipaemia, while laboratory alert thresholds may require different actions depending on the level of interference.

 

A multi-level control provides multiple challenge points, helping laboratories assess analyser performance across a range of HIL concentrations.

 

The Randox Acusera Serum Indices Control provides four HIL challenge levels, with haemolysis, icterus and lipaemia included at every level. The human-serum-based, commutable control is lyophilised, with a two-year shelf life, 14-day reconstituted stability at 2–8°C and true third-party independence for unbiased analyser performance assessment.

 

 

Why third-party QC?

 

Independence is an important principle of quality control. A true third-party control provides an external challenge to the analytical system rather than relying exclusively on the analyser manufacturer’s own processes.

 

For HIL testing, this means challenging the analyser’s ability to recognise haemolytic, icteric and lipaemic specimens correctly, rather than simply confirming that the instrument is operational.

 

From sample integrity to analyser confidence.

 

 

Laboratories use HIL indices because they recognise that sample integrity can affect analytical integrity. Once the HIL index becomes part of the decision-making process however, confidence in that index also becomes important.

 

The quality pathway can therefore be viewed as:

 

Sample integrity → Automated HIL detection → HIL QC verifies analyser response → Appropriate interference identification → Greater confidence in sample decisions → More reliable analytical results

 

HIL QC provides a means of challenging whether the system responsible for identifying compromised samples is itself performing as expected.

 

As laboratory networks become increasingly automated and interconnected, moving from assuming analyser fitness to demonstrating it is essential. HIL Quality Control helps move laboratories from assuming analyser fitness to demonstrating it, supporting confidence in every sample, every analyser and every result.