What are the steps involved in a hair analysis, and why does it take about one month to get the results?

To better understand why the processing time for a hair analysis averages 1 month after the sample collection date, we explain the process step by step below.

What is a hair analysis?

A hair analysis can be used to determine whether drugs or alcohol were used over an extended period of time. Drugs, medications, and alcohol enter the hair follicle through the bloodstream.

During the growth of new hair, very small amounts of the drug and/or its breakdown products (metabolites) are incorporated into the hair.

Blood samples are collected by an MLT (medical laboratory technologist) or a trained paramedical professional at one of our locations in Roeselare, Wezembeek-Oppem, Edegem, or Halen.

For more information about appointment options and business hours, please email us at info@testmijnbloed.be

How much hair is needed?

Depending on the number of substances to be tested, one or more pencil-thick strands of hair are collected from the crown of the head.

The hair is cut as close to the scalp as possible at the crown of the head. The hair that has grown most recently is located at the scalp.

What if someone doesn’t have any hair on their head?

Body hair grows more slowly and less evenly than head hair, making it more difficult to determine a reliable time frame. For this reason, we do not currently offer analyses of body hair.

Why aren’t you allowed to cut your own hair?

For a reliable analysis, the origin and direction of the hair must be correctly recorded. Therefore, the hair must not be cut by the patient beforehand. The sample is collected according to a standard procedure so that the patient’s identity can be verified and the integrity of the sample is guaranteed. Only in this way is it possible to ensure that the sample is collected and interpreted correctly, making it admissible for use in legal proceedings.

After collection, the sample is sent to a specialized clinical laboratory. That is where the most time-consuming part of the analysis begins.

How is the hair sample evaluated?

Based on an average hair growth rate of 1 cm per month, a 3-cm strand of hair indicates approximately 3 months of use or abstinence; a 4-cm strand, approximately 4 months; a 5-cm strand, approximately 5 months; and so on. Analysis is possible for hair lengths up to 6 cm. At 7 cm and longer, there is a risk that the measured substances become less and less reliable due to degradation or leaching, making drug residues more difficult to detect and quantify.

A positive result indicates that use occurred during the period under investigation, but does not specify the exact time. The entire hair segment is therefore analyzed. On the day of the sample collection, you can choose 1, 2, 3, 4, 5, or 6 cm.

In cases where the result was negative, no traces were found during the period under investigation.

Why don’t we offer segment analysis?

A segment analysis attempts to analyze hair on a month-by-month basis by examining each centimeter of hair separately. In reality, however, hair does not grow exactly 1 cm per month for everyone. The average hair growth rate varies between approximately 0.7 and 1.4 cm per month.

For example, if someone’s hair grows 1.2 cm per month, that theoretical monthly breakdown is no longer entirely accurate. As a result, it is impossible to determine with absolute certainty that a specific segment of hair corresponds exactly to a particular calendar month.

In addition, segment analysis is primarily used in forensic investigations. The lab also advises against this analysis for the following reasons:

• the limited reliability of precise time measurements,
• the large amount of hair required for this,
• and the significantly higher cost. The patient pays the price per drug to be analyzed per segment.

The hair is washed thoroughly

Before the lab can analyze what’s in the hair, everything on the hair must be removed.

That is why the hair is carefully washed several times to remove external contaminants such as sweat, smoke, dust particles, and hair products.

Equipment and Quality Control

The laboratory uses highly sensitive equipment capable of detecting minuscule amounts of substances. Each analysis is reviewed and evaluated by clinical biologists.

In addition to the analysis itself, the following takes place:

• quality checks,
• double-checking,
• Confirmation and Authorization
• and interpretation in accordance with the international guidelines of the Society of Hair Testing (SoHT).

This process takes time, but ensures that the final report is accurate and professionally substantiated.

Cut-off values and decision thresholds

Concentrations above the cut-off values (decision limits) are considered evidence of the presence of the corresponding drug.

The cutoff values used are based on the international guideline: “Consensus on Drugs of Abuse (DOA) Testing in Hair 2021” from the Society of Hair Testing (SoHT).

On the day of the sample collection, only the appearance and condition of the hair are assessed. No additional personal information is collected regarding the patient’s or client’s behavior or history.

The laboratory determines only the concentration of the requested substances in the hair and reports its findings based on the established threshold values.

A negative result means that no traces of the drug being tested or its metabolites were detected during the period under investigation.

A positive result means that traces of the drug or its metabolites were detected within the period under investigation, but does not provide an exact date of use within the analyzed period of 1 to 6 months.

How do I make an appointment?

Appointments for hair analyses can be made exclusively by email at info@testmijnbloed.be