All about Challenge Tests


What is a Challenge Test ?


A Challenge test is a means of comparing the respective quantities of minerals and heavy metals in two urine samples. The first sample is normally taken from an early morning specimen, whilst the second is sampled from a subsequent 24hr urine collection following the administration of a chelating agent.


Two such agents are typically used in Toxicological practice:


  1. DMPS – in Australia, this is administered intravenously in a solution of normal saline. The usual dose is 3mg/kg up to a maximum of 250mg. The solution is run in over one hour and all urine is collected over the following 24hrs. The volume of this collection is recorded, and a sample forwarded to the testing laboratory for analysis.                                                                                

  2. DMSA – this chelating agent is administered by mouth in the form of capsules, used in conjunction with the amino acid glycine. The dose is 20mg/kg as a single dose. The urine is again collected over 24hrs as per DMPS above. The advantage of this method is that it is simpler to administer and less expensive than an intravenous infusion. The downside is that only around 30-35% of an orally administered dose is absorbed by the gut; hence glycine is administered at the same time to enhance its absorption. In practice, using this approach, the results are similar in terms of the representation of toxic elements excreted; simply their quantities may differ. It is also safe to be given to children and is thus the preferred method to administer a Challenge Test in the paediatric age group.


How does it work?


Both DMPS and DMSA are relatively simple molecules, each containing two sulphydryl (-SH) groups.


They readily attach themselves to heavy metals, esp. mercury, as well as other elements such as copper, aluminium & nickel. The results are expressed as unit amount (metal or mineral) / gram creatinine. All the major commercial laboratories performing such tests provide their results in this format, due to the inter-individual variation in urine volumes received. Upon receipt of the test results, the treating Doctor or Practitioner can compare the excretion patterns before and after administration of the chelating agent, thereby obtaining vital information as to the propensity of the body to store both minerals and heavy metals.


In my practice, l always compare the two sets of data thereby obtained with the results of an hair analysis.


Some elements such as iron are much more readily assessed in hair, whilst mercury may only show a minor representation in hair and an early morning urine, yet be excreted in a substantial quantity in the post-chelation sample. This is due to polymorphisms (SNPs) in the genes encoding the MDR1 & MDR2 transport proteins, which are responsible for the excretion of mercury from the body. Such polymorphisms affect a significant proportion of the population, thereby reducing the transporting capacity of these proteins, often by a substantial amount.


The net result is that the unsuspecting Practitioner may completely miss a diagnosis of mercury toxicity, simply because it may not necessarily show to any great degree on standard hair tissue analyses.


This same principle also applies to some other heavy metals, esp. thallium, a widespread & highly toxic substance.


How much does it cost for a DMSA Challenge Test ?


The charges for this test consist of two separate parts:


Our charges cover the supply of the DMSA capsules, glycine tablets and a written comparative analysis of both the hair (HTMA) & urine (Challenge test) reports. This cost is AUD $150-00 within Australia.

Additional postage charges apply to overseas orders.


In addition, the Laboratory charges Euro 140.00 [70.00 (x2)] for standard profiles, or Euro 196.00

[98.00 (x2)] for more specialized tests. The (x2) is because each test consists of two urine samples, that have to be analysed separately.


The choice of test will depend upon the results of your prior hair analysis.


Initial payment must be made to Peninsula Clinical Nutrition by cheque, VISA / MasterCard or by bank transfer, whilst the second payment is made directly to the Laboratory, again by using either VISA or MasterCard. This second payment will be converted to your local currency at the time of processing by the Laboratory. This testing is performed in Germany.


How long do the results take to arrive ?


Normally 4-5 weeks from the time the samples are sent, depending on whether you select International Airmail (not recommended) or Courier services (recommended).


What happens next ?


After we have received your results, l will phone you to make an appointment to discuss them in detail. I will explain the significance of the test results and lay out the choices one may then make in regards to further testing and treatment options.


Treatment of heavy metal toxicities is highly individualized. What will work best for one person may not necessarily work well for someone else.


For example, simple detox measures and nutritional supplementation will be the obvious choice for some people, whilst chelation therapy will be indicated for more serious cases. Furthermore, some people may start off with a bout of chelation therapy to remove the bulk of the heavy metal burden, to be followed by a more extensive period of detox treatments to remove the remaining metals.

This is a commonplace scenario and is highly effective.


Can one do a Challenge test first without doing a prior hair test ?


In theory the answer is Yes, but in practice it’s almost never done.

The results from the hair test guide me in selecting which test panel to choose from, when ordering the Challenge test. Furthermore, one needs the three sets of results to make sense of what’s really going on.


Please note that all patients undertaking a Challenge test are also required to have a Functional Liver Detoxification Profile (FLDP test - Nutripath Laboratories), either before or after the Challenge test. This is needed because the correct dosing of DMSA for any subsequent chelation therapy is dependent both upon your body weight AND the results of the FLDP test.