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The relation between porphyrins and heavy metal exposure – how to detect your toxicity level?

The level of chemicals, metals and drugs in your body determine the status of your health. It is essential for you to know the levels of heavy metals in case you are at a risk of exposure to them.

What are porphyrins?

Porphyrins are natural chemicals in your body which assist in forming several essential substances in the body. They are essential components of proteins such as hemoglobin and myoglobin, the proteins in red blood cells and muscles respectively which carry oxygen in the blood and muscles.

Specific urine porphyrin profiles are associated with high-level exposure to mercury, arsenic, lead and some chemicals and drugs. Abnormal levels of urinary porphyrins are associated with genetic disorders, metabolic disturbances and diseases, anemias, oxidative stress, and high-level exposure to toxic chemicals or metals.

What does Porphyrins Profile measure?

Porphyrins profile measures the levels of porphyrins in your urine. The porphyrins profile checks for the presence of porphobilinogen and other types of porphyrins in the body such as uroporphyrinogen and coproporphyrinogen which are produced during heme biosynthesis.

Uses of Porphyrins Profile

The urine porphyrins profile assists in identification of your severity of heavy metal toxicity or organic chemical exposure. Heavy toxic burden or chemical exposure can have physiological effects resulting in impaired metabolism and cellular function. The urine porphyrins profile is used in detection of:

  • Oxidative stress
  • Toxic chemical or metal exposure
  • Anemia
  • Autism
  • Genetic disorders
  • Nutritional deficiencies

Interpretation of Porphyrins Profile

During heme biosynthesis, oxidized metabolites appear in the form of porphyrins and are readily excreted in urine when they accumulate as a result of inhibition of specific enzymes in the heme biosynthetic pathway. Heme is an essential compound required for oxygen binding, transport and utilization and electron transport in mitochondria. Due to the high rate of production of heme, urinary porphyrins have been used as early and sensitive biomarkers of disorders in heme production, associated with genetic disorders, metabolic disturbances and diseases, nutritional status, oxidative stress and high-level exposure to toxic chemicals and heavy metals.

We will review the relation between high levels of toxic metals such as Mercury (Hg), Arsenic (As) and Lead (Pb) to urinary porphyrins.


High levels of mercury in your blood result in accumulation of pentacarboxyporphyrinogen and coproporphyrinogen III due to inhibition of two enzymes in porphyrinogen metabolism -uroporphyrinogen decarboxylase and coproporphyrinogen oxidase (CPOX). Oxidation of those abnormally elevated porphyrinogens produces elevated urinary levels of total porphyrins, pentacarboxyporphyrin and coproporphyrin III. For instance, a study conducted on children with dental amalgams revealed specific urinary porphyrins as a biomarker for low-level mercury body-burden and that dental amalgams are a significant chronic contributor to mercury body-burden. Evidence has also shown twofold to threefold significantly higher Hg-associated porphyrins among children diagnosed with neurodevelopmental disorders in comparison to neurotypical children.

Precoproporphyrin is another mercury associated porphyrin as it comes after pentacarboxyporphyrin and before coproporphyrin I in the heme biosynthesis pathway. Precoproporphyrin appears to be elevated in mercury exposed individuals who carry a variant of the CPOX gene. There are three separate precoproporphyrin peaks which are reported separately along with the total precoproporphyrins-to-uroporphyrin ratio as uroporphyrin levels are not affected by mercury levels. It increases the sensitivity for detecting abnormalities in individuals with low heme biosynthesis which occurs in children with nutritional deficiencies or autism.

Arsenic - Elevated levels of uroporphyrins and coproporphyrin I and an elevated ratio of coproporphyrins (I: III) are found in case you are exposed to Arsenic. A study was done to investigate the effect of use of arsenic contaminated coal in heating, cooking and drying food in poorly ventilated dwellings. The excretion profile of the arsenic-exposed group which consisted of women, children and older age groups who stayed mainly indoors revealed significant increase in the levels of uroporphyrin and coproporphyrin III, indicating that porphyrins could be used as early warning biomarkers of chronic arsenic exposure in humans. Arsenic exposure is associated with skin changes, neuropathy, liver damage and cancer.

 Lead - A characteristic of lead poisoning is an increase in your urinary and serum δ-aminolaevulinic acid (ALA) and coproporphyrins in the absence of an increase in heme due to the inhibition of enzyme ferrochelatase and the associated loss of heme synthesis in the presence of a heavy metal such as lead. It produces an acquired porphyria known as plumbism, so-called because the symbol for lead is Pb. Erythroblasts which are precursors of red blood cells will acquire siderosomes as a result of the lack of enzymatic incorporation of iron into protoporphyrin IX, by heavy metal inhibited ferrochelatase. Siderosomes are histologically observable structures that result from iron deposition on mitochondria. Thus, the characteristic picture of lead poisoning has a strong correlation with porphyrins and affects various body systems.

Other drugs and chemicals - Various drugs include alcohol, sedatives, analgesics, antibiotics, estrogens and oral contraceptives which can suppress enzymes involved in porphyrin metabolism and affect your levels of urinary porphyrins. Likewise, exposure to hexachlorobenzene and dioxin has been associated with elevated levels of uroporphyrins and exposure to polyvinylchloride (PVC) and polybrominated biphenyl has been associated with elevated levels of coproporphyrins.

You must consult your doctor in case you suspect exposure to heavy metals and chemicals. A timely intervention will prevent and manage the long-lasting effects of acute or chronic exposure.