Trace/toxic Elements Flashcards
Essential element
If a deficiency impairs a biochemical or functional process and replacement of the element corrects this impairment
Trace elements vs ultratrace elements
- Trace = needed in mg/dl
- Ultratrace = needed in microgram/dl
Non-essential trace elements
Many are toxic and are thus of medical interest
List 5 important factors of elements that are important to the clinical significance of disease states or toxicity
- Absorption
- Transport
- Distribution
- Metabolism
- Elimination
Which blood collection tube is used for sample collection/processing upon suspicion of trace elements?
Royal blue stopper with or without EDTA
List trace element analytical methods
- Atomic emission spectroscopy
- Atomic absorption spectroscopy
- Inductively coupled plasma mass spectrometry
Atomic emission spectroscopy
- Quantify element by measuring intensity of emitted radiation from aerosolized sample
- Setup similar to spectrophotometer (flame or plasma -> light emission -> monochromator -> detector)
Atomic absorption spectroscopy
- Quantify element by measuring absorption of optical radiation by free atoms in gas phase
- Setup similar to spectrophotometer
Atomic absorption spectroscopy light sources
- Usually hollow cathode lamps (HCLs) and electrodeless discharge lamps (EDLs)
- Flame and graphite furnaces most common sources
ID the element
Most abundant metal in earth’s crust
Widely used in industrial and household ways
Corrosion-resistant
Lightweight
Aluminum
Aluminum mode of absorption
- Ingestion
- Inhalation
- Parenteral
- NOT TRANSDERMAL
What percent of aluminum concentrates in bone and lung?
50% bone and 25% lung
Aluminum health effects and toxicity
- Interferes with enzyme activity
- Encephalopathy, anemia, bone disease, progressive dementia
ID the element
Both metallic and non-metallic properties
In pesticides, pigments, manufacturing processes (wood-preservation)
Odorless/tasteless
Arsenic
Arsenic’s largest source of exposure
Food
One of the most common poisons in history
Arsenic absorption/transport
- Ingestion and inhalation
- Hepatic metabolism
Clearance of organic versus inorganic arsenic
- Organic arsenic rapidly cleared
- Inorganic and methylated forms are toxic
ID the element
Found in rice
Soft, bluish-white metal - can be cut with knife
Used in industry, contaminates soil
Cadmium
Cadmium absorption
- Ingestion (5%)
- Inhalation (10-50%)
- Higher in females + smokers than males + non-smokers bc iron stores different
Urine accounts for ___% of cadmium excretion and __% in bile
- 95%
- 2%
Cadmium health effects and toxicity
- No role in human physiology
- Affects liver, bone, immune system, blood, pulmonary, and nervous systems (everything)
ID the element
Used in making stainless steel
Has essential and toxic forms based on oxidation state
Chromium
Chromium absorption/transport
- Ingestion
- Inhalation
- Skin
- Transported bound to albumin and transferrin
Which forms of cadmium are essential or toxic?
Cr3+ is essential
Cr6+ is toxic and easier to absorb
Chromium health effects
- Lung irritation and dermatitis more common
- Liver, kidney, and immune system
ID the element
Relatively soft yet tough metal
Excellent electrical and heat conducting
Important cofactor for reduction of iron in heme synthesis
Copper
Copper absorption/transport/excretion
- Ingestion
- Inhalation
- Dermal
- Transported bound to albumin
- Bile accounts for 98% excretion, <3% in urine/sweat
Copper health effects and toxicity
- Important for many metalloenzymes
- Hepatic and renal damage
- Neurologic symptoms
- Mucous membrane irritant
- Wilson’s disease copper rings in eyes
Serum and urine copper levels in Wilson’s disease
Serum = normal or decreased
Urine = increased
Iron absorption
Ingestion (10% ingested is absorbed)
Ferric form must be reduced to Ferrous for absorption
Iron transport
Bound to proteins (ferritin)
Iron excretion
- Primarily by desquamation of epithelia
- RBC loss in urine/feces
- Menstruation
Iron health effects and toxicity
- Important for Hgb, Mgb, and enzymes
- Deficiency and overload states possible
- Stored as ferritin and hemosiderin in BM, spleen, and liver
- Iron deficiency in 15% world population
Lab eval of iron status
- Hgb
- RBC indices
- Total Fe
- TIBC
- % sat
- Transferrin
- Ferritin
Serum iron
Refers to ferric iron bound to transferrin, NOT the free iron circulating in plasma
Serum iron collection
Early morning collection preferred due to diurnal variation
No visible hemolysis
Transferrin
Primary plasma iron transport protein, which binds iron
Transferrin saturation
25-30%
Unsaturated iron binding capacity (UIBC)
Additional amount of iron that can be bound (empty binding sites left on transferrin)
Total iron binding capacity (TIBC)
Theoretical amount of iron that could be bound if transferrin and other minor iron-binding proteins present in serum/plasma were saturated
TIBC calculation
TIBC = transferrin X 1.18
Percent saturation
- Transferrin saturation
- Ratio of serum iron to TIBC
- % sat = 100 X serum iron/TIBC
Ferritin
Major iron storage protein
Concentration of ferritin is directly proportion to what?
Total iron stores in body
More sensitive and reliable test for iron deficiency
Ferritin
Iron deficiency serum iron, transferrin, ferritin, percent sat, and TIBC relative values
Serum iron = lower
Transferrin = higher
Ferritin = lower
Percent sat = lower
TIBC = higher
Iron overdose serum iron, transferrin, ferritin, percent sat, and TIBC relative values
Serum iron = higher
Transferrin = lower
Ferritin = higher
Percent sat = higher
TIBC = lower
ID the element
Soft, bluish-white, highly malleable/ductile
Used to be put in gas and paint
Lead
Lead absorption
- Ingestion and inhalation
- 99% absorbed by RBC
- Liver, kidney, and brain with highest in bone (90%)
Lead excretion
- 76% urine
- 16% feces
- Remainder in sweat, hair, and nails
Lead health effects and toxicity
- No physiological role
- Higher absorption in kids
- Neurological symptoms and low IQ
- Anemia
ID the element
Used in production of steel
Manganese
Manganese absorption
- Mainly ingestion
- Inhalation and dermal limited
- Found mostly in fat and bone
Manganese excretion
Bile accounts for majority of excretion
Manganese health effects
Important for many metalloenzymes and enzyme activation
Manganese deficiency effects
Clotting issues, dermatitis, elevated serum Ca/phosph/ALP
Manganese toxic effects
Nausea, vomiting, headache, disorientation, anxiety, compulsive laughing or crying (manganese madness)
ID the element
Quicksilver, heavy/silvery metal, liquid at room temp
3 oxidation states
Mercury
H^0, Hg1+, Hg2+
Mercury absorption
- Inhalation most common
- Ingestion, cutaneous, injection, and dental
Mercury major storage organ
Kidney
Mercury excretion
Fecal and urinary
Mercury health effects an toxicity
- No physiologic role
- CNS and PNS toxicity
- Can damage most organs/tissues before symptoms occur
Molybdenum absorption
- Up to 80% by ingestion
- Mainly liver, skeleton, kidneys
Molybdenum bound to
Alpha-macroglobulin and RBC membranes
Molybdenum excretion
Urinary
Molybdenum health effects and toxicity
- Important cofactor for several enzymes
- Deficiency and toxicity rare
ID the element
Used in electronic industry, nutritional supplements, pigments, pesticides, dandruff shampoos, and fungicides
Selenium
Selenium absorption
Ingestion most common (up to 50% of diet)
Selenium excretion
- Mainly urine
- Some in sweat and exhalation
Selenium health effects and toxicity
- Important antioxidant
- Thyroid hormone synthesis
- Deficient states -> cardiomyopathy
- Toxic states -> GI, tachycardia, CNS symptoms
ID the element
Bluish-white lustrous metal
Stable in dry air
Covered in white coating upon moisture exposure
Zinc
Zinc absorption
- Ingestion most common
- Mainly muscle (60%) and bone (30%)
- RBCs absorb most zinc in blood (80%)
Zinc excretion
Feces
Zinc health effects and toxicity
- Important for enzyme activity, DNA/RNA, membrane structure…etc
- Deficiency -> growth inhibition, testicular atrophy
- Toxicity rare
- Counteracts copper in Wilson’s disease
