Hair elemental analysis, (when performed properly), can serve as a highly accurate and qualitative screening test for exposure to toxic metals. But due to some of its limitations, namely that it is not considered capable of detecting acute toxicity (i.e. those stemming from a more immediately recent exposure) it is therefore not considered an acceptable method of diagnosing ‘metal toxicity’ in the conventional medical use of the term.
An Issue in Terms
The issue of differentiating ACUTE heavy metal ‘toxicity’ (aka ‘poisoning’) from the far more prevalent (albeit hard to quantify) situation of CHRONIC heavy metal ‘toxicity’, has led to much of the misunderstanding about the uses and credibility of clinical hair
analysis.
How do we therefore assess the all too common possibility of a chronic and accumulating toxic metal burden that may be impacting our client’s long term health status over time?
Hair is in fact an excretory tissue, that can provide a chronological record of bioavailable trace elements in the body. Once metals are incorporated into growing hair there is no ‘back exchange’ into the body. Therefore, the concentration of metals in hair is usually far greater than in the blood or urine. The length of the hair specimen analysed dictates the duration of time during which the exposure occurred (and segmental analysis of hair can even be used forensically to estimate the chronological course of exposure).
What is the Clinical Evidence?
A growing number of peer-reviewed publications support the considerable value of elemental analysis of hair specimens, especially for the toxic metals, in clinical practice. For example
- Elevated levels of Arsenic in both hair and urine confirmed arsenic toxicity from pesticide exposure in an individual with peripheral neuropathy and macrocytosis.
- There is correlative evidence linking hair levels of Lead, Manganese, Cadmium, and other toxic metals with psychological conditions such as anxiety, depression and even violent behaviours.
- Lead, cadmium and mercury levels in children’s hair has even been correlated with childhood intelligence.
- School children with relatively high levels of lead in their hair had slower reaction-times and less flexibility in changing their focus of attention than children with relatively low concentrations.
- History of fish consumption and mercury in hair samples are considered the best indicators of human exposure to methylmercury. Fish consumption among Scandinavian men was positively correlated with hair and blood mercury levels, and acute myocardial infarction.
- By using a leading hair analysis laboratory for the detection of 14 different elements, one team of investigators could distinguish between children with and without learning disabilities with a 98% accuracy rate.
Clinical Utility
- An important advantage to hair analysis is that the sample collection is so simple and non-invasive, as well as easily stored and transported.
- Hair analysis provides a useful screening tool for long-term trace element status and recent time-averaged exposure to potentially toxic metals over the medium-term.
- Beyond this broad use, other more specific and relevant clinical applications of elemental hair analysis include mental disorders, cystic fibrosis, coeliac disease, growth retardation, and diabetes.
- Qualified and trained clinicians are aware of the degree of inter-laboratory variation (and remain wary of laboratories that recommend nutritional supplements on the basis of their results).
- Qualified and trained clinicians only utilise laboratories that can validate their certification and their methodologies for washing, digesting and analysing hair specimens.
- This clinic only recommends laboratories that employ appropriate quality control characteristics and the validation of the establishment of reference ranges, accuracy, precision and reliability of state of the art hair analysis.
Lab Accuracy
Trace element analysis in biological samples has improved significantly over the last 40 years. Improvements in instrumentation and techniques such as inductively coupled plasma-mass spectrometry (ICP-MS), sample washing (to remove contaminants) and microwave digestion have resulted in improved precision, accuracy, reliability, and detection limits.
The analysis of human scalp hair has benefited significantly from these improvements. An article in the Journal of the American Medical Association found significant inter-laboratory variation amongst several laboratories performing trace metal hair testing. It concluded that standardisation was necessary to improve inter-laboratory comparability, and an accompanying commentary described the characteristics of a laboratory that should be used in performing hair analysis. This led to a study by Bass et. al. in 2001 that set out to demonstrate which laboratory practices will provide precise, accurate, and reliable hair element results as well as a method for establishing accurate reference ranges. After demonstrating the use of a prescribed clinical quality control process, including method validation, proficiency testing, split sampling, and good laboratory practices, it was clearly demonstrated that measuring trace elements in hair can be analytically valid, and the process by which the Doctor’s Data Laboratory has become known was confirmed.
Conclusions:
- Hair Element Analysis does NOT provide a quantitative ‘inventory’ of the body’s mineral levels, but instead a qualitative ‘screening tool’ for assessing mineral relationships and ratios as well as strong correlations between hair toxic metals and body tissue levels.
- When conducted and interpreted appropriately (according to current evidence) it is one of the most affordable, non-invasive and yet powerful biochemical assessments that can be made in clinic.
- Lab methodology matters.