Blood Spot ICPMS Toxic and Essential Elements

Lead is a non-essential heavy metal with no physiological role. It accumulates in bone, red cells, and soft tissues over years of exposure and interferes with haem biosynthesis, mitochondrial function, and neurotransmission. The half-life in blood is approximately one month, in bone decades.

Blood lead reflects recent exposure and a fraction of total body burden. Chronic low-level exposure affects cognition and cardiovascular health in adults; even low concentrations harm neurodevelopment in children. Blood lead guides chelation decisions in acute poisoning and monitors occupational or environmental exposure.

Mercury exists as elemental vapour, inorganic salts, and organic methylmercury. Methylmercury from fish accumulates in red cells and crosses the blood–brain barrier; inorganic mercury binds sulfhydryl groups in kidney and other tissues. Blood mercury reflects recent methylmercury exposure; urine better captures inorganic mercury.

Elevated blood mercury in the absence of occupational exposure typically indicates dietary fish intake, particularly large predatory species. Chronic exposure affects the nervous system, kidneys, and cardiovascular system. Prenatal methylmercury exposure impairs foetal neurodevelopment.

Cadmium is a toxic metal released from industrial processes, batteries, and tobacco smoke. It accumulates in kidney cortex with a biological half-life of 10–30 years. Cadmium displaces zinc in metallothionein and inhibits DNA repair enzymes.

Blood cadmium reflects recent exposure and is elevated in smokers; urine cadmium better reflects cumulative body burden. Chronic cadmium toxicity causes proximal tubular dysfunction, osteoporosis, and is a human carcinogen.

Arsenic exists as inorganic (toxic) and organic (seafood-derived, largely non-toxic) species. Inorganic arsenic undergoes hepatic methylation to monomethyl- and dimethylarsenic acids, which are renally excreted. Blood arsenic has a short half-life (hours to days) so reflects very recent exposure.

Blood arsenic is useful in acute poisoning but less informative for chronic exposure than urine. Elevated values require speciation to exclude benign seafood arsenic. Chronic inorganic arsenic exposure causes skin lesions, peripheral neuropathy, vascular disease, and cancer.

Aluminium is ubiquitous in the environment but poorly absorbed from the gastrointestinal tract in healthy individuals. It is renally excreted, so accumulates in renal impairment. Aluminium competes with iron and magnesium and can deposit in bone and brain.

Elevated aluminium is classically seen in patients on chronic dialysis (dialysis dementia) or receiving aluminium-containing phosphate binders. Occupational inhalation and contaminated parenteral nutrition are other sources. Blood aluminium is less reliable for chronic body burden than bone or urine in provoked testing.

Zinc is an essential trace element and cofactor for over 300 enzymes involved in nucleic acid synthesis, immune function, wound healing, and antioxidant defence. Whole blood or serum zinc reflects recent intake and redistribution during inflammation; cellular or functional assays (e.g. red-cell zinc, alkaline phosphatase) may better assess status.

Zinc deficiency impairs growth, immune function, and wound healing and is seen with malabsorption, chronic liver or kidney disease, and inadequate intake. Excess zinc from supplementation can induce copper deficiency. Blood zinc falls during acute inflammation, complicating interpretation.

Copper is an essential cofactor for enzymes involved in mitochondrial respiration, connective tissue synthesis, neurotransmitter production, and iron metabolism. Most circulating copper is bound to caeruloplasmin, an acute-phase protein, so blood copper rises in inflammation, pregnancy, and oral contraceptive use.

Low copper indicates deficiency (malabsorption, excessive zinc, Menkes disease) or hypocaeruloplasminaemia. High copper is seen in Wilson disease (with low caeruloplasmin), inflammatory states, and oestrogen exposure. The copper:zinc ratio is used in functional medicine to assess inflammatory balance, though its clinical utility is debated.

Selenium is an essential trace element incorporated into selenoproteins, including glutathione peroxidases and thioredoxin reductases, that protect against oxidative stress. Blood selenium reflects recent intake; long-term status is better assessed by erythrocyte or toenail selenium.

Deficiency impairs immune function, thyroid hormone metabolism, and antioxidant defence and is endemic in low-selenium soils. Excess selenium (>400 µg/L) causes selenosis with hair loss, nail changes, and neuropathy. Selenium supplementation in deficient populations may reduce cardiovascular and cancer risk, though trial data are mixed.

Magnesium is the fourth most abundant cation in the body and a cofactor for over 300 enzyme systems, including those regulating ATP, protein synthesis, and neuromuscular transmission. Ninety-nine per cent is intracellular or in bone; serum represents less than one per cent of total body magnesium, so deficiency can exist with a normal serum level.

Hypomagnesaemia causes neuromuscular irritability, arrhythmias, and potentiates hypokalaemia and hypocalcaemia. It is seen with diuretics, proton-pump inhibitors, alcohol use, and gastrointestinal losses. Serum magnesium is insensitive for chronic deficiency; red-cell or ionised magnesium may be more informative. Hypermagnesaemia is rare and typically iatrogenic or occurs in renal failure.

The copper:zinc ratio is a derived marker used in functional and integrative medicine as a proxy for oxidative stress, inflammation, and hormonal balance. Copper (bound to caeruloplasmin, an acute-phase protein) rises with inflammation and oestrogen, while zinc falls; the ratio amplifies these changes.

An elevated Cu:Zn ratio has been associated with inflammation, cardiovascular risk, and mood disorders in observational studies, but its independent predictive value is contested. The ratio is influenced by acute-phase responses, supplements, and analytical variability, limiting its specificity. It is used in functional practice to guide zinc or anti-inflammatory interventions, but mainstream guidelines do not endorse it as a standalone diagnostic tool.