Heavy Metal Testing – One of the Most Commonly Ordered, Yet Poorly Understood Tests

Heavy (or toxic) metal testing is very common amongst holistic / alternative / natural / integrative / functional doctors, however there is a lot of misunderstanding about the various testing methods and interpretation of the results.  This is unfortunate because toxic metals can cause a myriad of symptoms and can easily be treated, so it is important to properly assess heavy metal levels when attempting to improve your health.

The first step in assessing whether or not someone has a toxicant burden is by remembering the acronym “SET.” 

  • Symptoms – are symptoms consistent with one, or more, toxic metal? (I will go into more detail about symptoms related to the most common metals in future posts).  Or could a toxic metal burden be interfering with someone’s ability to get better?
  • Exposure – does someone have a possible exposure?   Have they lived in a home built prior to 1978 (lead)? Do they have a history of eating tuna or sushi? Dental amalgams?
  • Timing – did the onset of symptoms occur with exposure?  Some toxic metals accumilate over time, like lead accumulation in Parkinson’s disease.  Also, lead is stored in bones so can begin to be released in women when they enter menopause and bone density diminishes.

How to Test for Toxic Metals?

Where to look in the body for toxic metals is important for proper assessment.  If someone is concerned about a current (acute) exposure, blood, urine and hair are all reasonable places to look, however assessing total body burden is more complex. Toxic metals have a short half-life in the blood, then move into tissues for storage.  Testing blood or hair levels will only demonstrate a recent exposure, but not total body burden. 

Urine levels of toxic metals also reflect acute exposure, but provoked urine levels indicate total burden.  Metals will “pool” in certain tissues or organs which would not be practical for testing.  These metals can move into other compartments, such as urine, that reflect tissue and organ levels.  Provoking with a chelating substance (chelate just means “to bind”) pulls stored levels of toxic metals out of tissues and organs.  This is known as a metal mobilization test (MMT).  It is total body burden of toxic metals that are important to assess in chronic illnesses such as fatigue, cognitive issues, neurological conditions, immune dysfunction and depression.

Provoking dose for testing = 30mg/kg of body weight of DMSA prior to 6-hour urine collection

Interpreting test Results

Interpreting provoked urine metal results can be confusing if the patient or practitioner is not aware of established reference ranges.  Doctors Data laboratory is most commonly used for urine toxic metal testing, and many don’t realize the reference range is for an unprovoked sample.  A provoked sample will almost always look elevated when compared to the unprovoked range.  I have seen patients come to our clinic for treatment who were diagnosed with heavy metal toxicity based on this improper interpretation.  The physician also needs to determine what an “actionable level” is based on the following information.  

The best way to assess heavy metal burden is to collect a first morning urine in one test kit, then another test kit, collect urine for 6-hours after taking DMSA based on the above equation.  The first morning sample will demonstrate any recent or ongoing metal exposure based the lab’s reference range, or preferably the CDC’s 4th Report.  The 6-hour urine results will indicate the amount the body released over that period of time.  

False negative results can be identified if mercury levels do not increase at least 10 fold from first-morning urine to provoked urine, or if cadmium levels do not increase at all.  If this happens, the patient may not have absorbed the DMSA, likely due to gluten sensitivity or small intestine bacterial overgrowth (SIBO).  Another common issue is low glutathione levels which reduce the bodies ability to excrete toxic metals.  Some people need to take NAC or glutathione for a few weeks prior to collection.

The Take Home

Proper assessment of total body burden of heavy metals levels requires testing baseline urine and a provoked sample.  Proper interpretation of the results requires looking at relative increase from pre-flush to post-flush urine, and understanding what a treatable level is.  Taking these steps will ensure you have been properly assessed for toxic metals.

This is Part I of a multi-part post about toxic metals.  Look for future posts on sources of toxic metals and symptoms they cause.