MLS Clinical Chemistry 1 - Trace Elements PDF

MLS 301 CLINICAL CHEMISTRY 1 LABORATORY FINALS | 3RD YR...

MLS 301 CLINICAL CHEMISTRY 1 LABORATORY FINALS | 3RD YR FIRST SEMESTER LESSON 11: TRACE ELEMENTS I. TRACE ELEMENTS ALUMINUM TOXICITY INTRODUCTION SIGNS AND SYMPTOMS: Dietary requirements - levels established by WHO as the smallest - Encephalopathy (stuttering, gait disturbance, myoclonic amount to maintain optimal function and health jerks, seizures, coma, and abnormal EEG) - “All substances are poisons... dose differentiates a poison.” - Osteomalacia or aplastic bone disease (painful spontaneous Each of the essential and nonessential trace mineral elements fractures, hypercalcemia, and tumorous calcinosis) CAN BE TOXIC when present in high concentrations. - Proximal myopathy, Increased risk of infection - Microcytic anemia, Increased left ventricular mass and TRACE ELEMENTS / MICRONUTRIENTS decreased myocardial function. naturally occurring, homogeneous, inorganic substance required Seen in px with RENAL INSUFFICIENCY in humans in amounts less than 100 mg/day - dialysis (aluminum-contaminated solutions or oral agents have specific in vivo metabolic functions which cannot be that contain aluminum) effectively performed by other elements Prolonged intravenous feeding of infants - aluminum-contaminated formula may lead to neurologic CATEGORIES development Elements are categorized based upon their biological effect, diseases that occur due to their deficiency & toxicity due to LAB EVALUATION overdose Specimens: Urine and Serum 1. Essential elements - deficiency impairs a biochemical reaction Methodologies: and replacement of the element corrects the impairment - ICP-MS : Inductively coupled plasma mass spectrometry 2. Possibly essential elements - GFAAS: Graphite furnace atomic absorption spectroscopy 3. Nonessential elements - primarily of medical interest because of their TOXICITY. ARSENIC (NE) - Usually consists of metals except selenium and the Food is the largest source of arsenic exposure, with lower halogens fluoride and iodine amounts coming from drinking water and air Most commonly found in fish and seafood ROLES OF TRACE ELEMENTS Mainly used as a wood preservative 1. Structural signal transduction and special catalytic properties Arsenobetaine- main arsenic found in seafood 2. Some trace elements are components of metalloenzymes and Arsenic trioxide- white, odorless, tasteless powder and one of the most metalloproteins acting as cofactors common poisons in human history 3. Provides electron and oxygen transport - approved as tx for acute promyelocytic leukemia (M3) 4. Maintenance of macromolecule conformation 5. Influences vitamin or hormonal activity Acute exposure: gastrointestinal, bone marrow, cardiovascular, central nervous system, renal and hepatic symptoms CONCENTRATIONS IN THE BODY Chronic exposure: Iron, Copper, Zinc: Found in parts per million (mg/L) - dermatologic Selenium, Chromium, Manganese: Found in parts per billion (ug/L) o Mees' lines - white, transverse lines on fingernails o hyperkeratosis, hyperpigmentation, and alopecia ALUMINUM (NE) - hepatic damage and malignancies crystalline silver-white ductile metal - cardiovascular - Black foot disease most abundant metal in the earth’s crust o gangrenous tissue damage due to PVD) good conductor of heat and electricity - CNS ("socks and glove" neuropathy and tremor) found in consumer products such as antacids, astringents, - “Black foot disease” and PVD buffered aspirin, food additives, cosmetics, and antiperspirants Mode of exposure: orally, through inhalation and parenterally arsenic poisoning- patient have characteristic metallic taste and plasma: bound to carrier proteins such as transferrin garlicky breath Concentration in organs: Bone: 50% | Lung tissues: 25% Excretion: Urine: 95% | Bile: 2% FORMS OF ARSENIC 1. Organic forms- arsenocholine and arsenobetaine EFFECTS AND TOXICITY - non-toxic and are cleared rapidly known to produce encephalopathy 2. Methylated form- monomethylarsenic (MMA) and similar to that seen in Alzheimer’s disease dimethylarsenic (DMA) prolonged ingestion from OTC drugs may cause adverse effects - intermediate in toxicity breathing large amounts of aluminum dusts can result to lung 3. Inorganic forms- As(V), As(III) | highly toxic problems: Coughing, Changes that show up in chest X-rays 1 shainlee periabras  ARSENIC TOXICITY COPPER TREATMENT FOR POISONING: Lavage and Activated charcoal Third most abundant trace element in the human body after ANTIDOTES- Chelating agents: zinc and iron - Dimercaprol (a.k.a British anti-Lewisite) RICH SOURCES: liver, shellfish, chocolate, nuts, and seeds - Penicillamine and succimer Copper is present in all living cells and functions mostly as a component of the cuproenzymes and copper-containing proteins. LAB EVALUATION Specimen: Urine (due to the short half-life of arsenic in blood) ROLES OF COPPER Methodologies: ICP-MS, GFAAS Involved in electron transport and oxidation reactions - HG-AAS: Hydride Generation Atomic Absorption Spectroscopy Essential for cellular respiration, neurotransmitter regulation, collagen synthesis, and nutrient metabolism and as an CADMIUM (NE) antioxidant against free radicals. important cofactor for several metalloenzymes and is critical for Smokers of tobacco products have about twice the cadmium level their bodies than in nonsmokers. the reduction of iron in heme synthesis. nonsmokers: primary exposure to is through ingested food 90% is excreted through feces COPPER ABSORPTION Absorption decreased by: Zinc or iron intake and ascorbate CADMIUM TOXICITY Absorption enhanced by: Histidine, gluconate, citrate Newly absorbed copper is transported bound to albumin and Toxicity is due to formation of protein-cadium adducts which can lead to protein denaturation transcuperin Cleared from the circulation by the liver Renal dysfunction is common When copper reenters circulation, it is bound to ceruloplasmin & TREATMENT: Chelation using EDTA metallothionein: transports 65%–90% of the plasma copper CHROMIUM (E) COPPER-CONTAINING ENZYMES (CUPROENZYMES) from the Greek word chroma (“color”) maintaining normal metabolism of glucose, fat, and cholesterol Plasma amine oxidases- Catabolize some active amines such as tyramine, histidine, and polyamines SOURCES: meats, whole grains, green beans, broccoli, and some spices - Inactivate the catecholamines (norepinephrine, tyramine, EXISTS IN 2 MAIN VALENCY STATES: dopamine, and serotonin) 1. Trivalent (Cr3+)- ESSENTIAL Lysyl oxidase- Helps collagen proteins cross-link into larger fibers | Have anticancer activity - Enhances the action of insulin 2. Hexavalent (Cr6+)- Better absorbed, MORE TOXIC than Cr3+ Cytochrome-c oxidase- catalyzes cellular utilization of oxygen Superoxide dismutase- scavenge & reduce superoxide radicals - Oxidizing agent that can induce cellular apoptosis through formation of free radicals - Contact with salts produces contact dermatitis and skin ulcers COPPER-CONTAINING PROTEINS Ceruloplasmin – transports Cu Albumin & transcuperin CHROMIUM DEFICIENCY Metallothionine - sequesters and stores copper Insulin resistance: glucose intolerance, glycosuria Clotting factor V Hypercholesterolemia: decreased longevity Decrease Sperm Count: impaired fertility, peripheral neuropathy GENETIC COPPER DEFICIENCIES CHROMIUM TOXICITY MENKES' SYNDROME Severe dermatitis and skin ulcers Rare X-linked recessive congenital defect of copper absorption May irritate the respiratory tract resulting in airway irritation, that usually has clinical onset by 3 months of age airway obstruction, andpossibly lung cancer S/S: poor mental development, failure to keratinize hair, skeletal inhaled: affects lung, kidneys, liver, skin, & immune system problems, and degenerative changes in the aorta. brittle hair (steely) is “KINKY” or twisted, and poor skin and hair pigmentation, hypothermia, and seizures have been reported. LAB EVALUATION INCREASED serum ceruloplasmin SPECIMEN: Plasma, Serum, Urine METHODOLOGIES: GFAAS, ICP-MS ACQUIRED COPPER DEFICIENCIES - NAA: Neutron activation analysis Deficiencies have been observed in - Premature babies COBALT (E) - Patients with malabsorption syndromes Vitamin B12 constituent - Malnourished infants and adults Essential for folate metabolism, erythropoiesis and hgb synthesis Deficiency may lead to megaloblastic anemia - Long-term hyperalimentation Measure by AAS - Individuals with sickle cell disease receiving zinc therapy - Treatment copper-chelating agents like penicillamine shainlee periabras 2  GENETIC COPPER ACCUMULATION DISEASE Chronic manganese toxicity resembles Parkinson's disease WILSON’S DISEASE (HEPATOLENTICULAR DEGENERATION) with akinesia, rigidity, tremors and mask-like faces deposition in brain is seen w/ biliary atresia in children Autosomal recessive disease that results from impaired biliary LOCURA MANGANICA (MANGANESE MADNESS) - described in copper excretion Chilean manganese miners with acute manganese aerosol Usually presents at ages of 6 and 40 years. contamination Excess copper is deposited in the liver and in the basal nuclei of the brain, causing sclerosis and hepatitis Abnormalities of kidney, cornea, and brain may occur. IRON Kayser-Fleischer rings (green-brown discoloration) in the Ferrous (Fe2+) and ferric (Fe3+) irons cornea caused by copper deposition fourth most abundant element in the earth’s crust and the most DECREASED ceruloplasmin abundant transition metal - No excretory system is used for excess iron FLUORIDE Primary means of iron regulation Used to prevent dental caries and minimizes bone loss - Absorption of iron from the intestine Stimulates bone formation lost primarily by desquamation & red cell loss to urine and feces. Fluoridation of drinking water reduces the incidence of tooth With each menstrual cycle, women lose apporximately 20-40 decay now for more than 60% of the U.S. population and reduces mg iron the incidence of tooth decay by more than 60% Excess free iron in the body catalyze the formation of toxic free Excreted primarily through the kidneys radicals (prooxidant) contributing to lipid peroxidation, atherosclerosis, DNA damage and carcinogenesis 3-5 g of iron in the body FLUORIDE TOXICITY - 2-2.5 g --> hemoglobin, mostly in RBC and its precursors. 1. Calcification of soft tissues - 130mg is found in myoglobin 2. DENTAL FLUOROSIS - unsightly mottling of dental enamel, is - 8mg is found in enzymes like peroxidases, cytochromes and seen in erupting teeth of children and is caused by excessive many of Kreb cycle's enzymes fluoride possibly from ingestion of fluoride- containing toothpaste Iron is stored as ferritin or hemosiderin primarily in the bone marrow, spleen or liver. IODINE - Hemosiderin is formed when ferritin is broken down. Dietary iodine (I) is normally ingested as iodide and is the basic Only 3-5 mg of iron is found in plasma bound to transferrin, element in the synthesis of thyroid hormones albumin and free hemoglobin. transported to thyroid follicles, where it is trapped & concentrated to several hundred-fold over its concentration in serum IRON DEFICIENCY TSH stimulates thyroid gland to trap iodine and incorporate iodide into tyrosines forming thyronines within the follicular lumen Affects 15% of the worldwide population AT RISK: pregnant women, young children, adolescents, women of reproductive age IODINE DEFICIENCY Caused by increased blood loss, decreased intake or decresed results in inadequate thyroid hormone and hypothyroidism. release from ferritin 1. Mental retardation and cretinism- effect of congenital IDA – MOST COMMON ANEMIA IN THE PLANET hypothyroidism in children 2. Myxedema - hypothyroidism in adults results in mental status changes, and hypotension 3. Development of goiter MANGANESE constituent of many important metalloenzymes, including superoxide dismutase, pyruvate carboxylase, arginase, and glycosyl transferases Normal component of tissue and highest levels are found in fat IRON TOXICITY and bone Hemochromatosis - iron overload with or without tissue damage Food sources include whole grain foods, nuts, leafy vegetables, - associated hereditary hemochromatosis (HH) leading to soy, and teas abnormally high iron absorption - affects liver function, and often leads to hyperpigmentation MANGANESE DEFICIENCY of the skin results in low plasma cholesterol, impaired glucose tolerance, Hemosiderosis - iron overload without a demonstrable tissue damage. skeletal abnormalities, dermatitis, color changes in hair, & reduced blood-clotting function not responsive to vit K LAB EVALUATION Disorders of iron metabolism are evaluated by MANGANESE TOXICITY - Hematocrit & hemoglobin, RBC count & RBC indices causes nausea, vomiting, headache, disorientation, memory loss, - Total iron level, Percent saturation, Transferrin anxiety and compulsive laughing or crying - Ferritin, TIBC (Total Iron-binding Capacity) shainlee periabras 3  TOTAL IRON CONTENT (SERUM IRON) IQ declines are seen in children with blood lead levels (BLL) of 10 Refers specifically to the Fe3+ bound to transferrin ug/dL or higher Heparinized plasma may be used CNS symptoms: clumsiness, gait abnormalities, headache, - Oxalate, citrate, EDTA binds iron and are all unacceptable behavioral changes, seizures & severe cognitive problems Early morning sample is preferred because of diurnal variation GI symptoms: abdominal pain, constipation and colic Others: nephropathy, ANEMIA, peripheral neuropathies, motor weakness, chronic renal insufficiency, systolic hypertension TOTAL IRON BINDING CAPACITY (TIBC) amount of iron that could be bound by saturating transferrin and LEAD EXPOSURE other minor-iron binding prot. present in serum or plasma sample. Direct measure of the available transferrin receptors Childhood exposure: usually through paint chips All methods require addition of excess iron to saturate transferrin Occupational exposure: smelting, mining, ammunitions, Excess iron is removed by adding magnesium carbonate to soldering, plumbing, ceramic glazing and construction industries measure the bound iron Absorbed lead is excreted primarily in urine (76%) and feces IDA have high TIBC; non-iron deficiency anemias have low TIBC. (16%) and the remaining 8% in hair, sweat, nails and others PERCENT SATURATION LAB METHODOLOGIES It is also known as the transferrin saturation SPECIMEN: AN INDEX OF IRON STORAGE - WHOLE VENOUS BLOOD- Preferred over serum or plasma It is the ratio of serum iron to TIBC since majority of lead is found inside red cells This ratio is around 1/3 for normal individuals, and in IDA it is - URINE : useful for detecting RECENT exposure or significantly reduced to values of around 1/5 or lower monitoring of chelation therapy Increased: iron overdosage, hemochromatosis, sideroblastic anemias RADIOGRAPHIC METHODS: measure amount of lead in bones Decreased: IDA (lowest), malignancy, chronic infection, anemia of Others: plasma aminolevulinic acid, whole blood Zinc chronic disease. protoporphyrin, free erythrocyte protoporphyrin REFERENCE VALUES: 20-55% (conventional) %saturation = total iron (ug/dL)/TIBC x 100 MERCURY Also called quicksilver. LAB METHODOLOGIES Three naturally occurring oxidation states: Hg(0) , Hg+ , Hg2+ 1. COLORIMETRY: Uses HCl and ferrozine→ (+) blue color Organic mercury: Hg2+ attached to carbon atoms - Iron dyes: bathophenanthroline, tripyridyltriazine Mercury is used in dental amalgams, electronic switches, 2. ANODIC STRIPPING VOLTAMMETRY germicides, fungicides and fluorescent light bulbs - first step in quantitation of serum iron is separation from OTC drugs like topical antiseptics, stimulant laxatives, diaper- transferrin. rash ointment, eye drops, nasal sprays and eye cosmetics serum iron is falsely elevated by hemolysis and affected by especially mascara diurnal variation ROUTES OF EXPOSURE: - iron is highest in the morning and lowest at night - Inhalation, primarily elemental mercury vapor - Ingestion of HgCl2 and mercury- containing foods such as LEAD predatory fishes plays no known role in normal human physiology - Cutaneous absorption of methyl mercury through the skin and even through latex gloves - Lead-based household paints was banned in the US in 1972 - Injection of liquid mercury & mercury- containing tattoo - has been massive recall of toys from China. pigments Exposure is primarily gastrointestinal and respiratory 99% of absorbed lead is taken up by erythrocytes where it - Dental amalgams interferes with heme synthesis kidney is the major storage organ after elemental or inorganic mercury exposure LEAD POISONING Hg is efficiently absorbed and distribute to tissue including brain LEAD BLOCKS THE ACTION OF : Movement of MeHg across blood- brain barrier is dependent on - δ-aminolevulinic acid (ALA) synthetase cysteine - δ-ALA dehydratase (ALAD) Has no known function in normal human physiology - coproporphyrinogen decarboxylase Mercury is toxic to both CNS and PNS - Ferrochelatase → producing ANEMIA THIMEROSAL- Mercury-containing vaccine preservative lead blocks two other enzymes: - pyrimidine-5′-nucleotidase and Na-K dependent ATPase FORMS OF MERCURY - resulting in diminished energy supply for red blood cells, Elemental mercury vapors: highly absorbed and highly toxic; harmful leading to decreased cell membrane integrity. effects on nervous, digestive and immune systems Because pyrimidine-5′-nucleotidase is required for removal of Liquid elemental mercury: poorly absorbed and relatively nontoxic clumped intracellular RNA, lead inhibition of this enzyme results Inorganic salts: affects the skin, eyes, GIT and kidneys in clumping of RNA complexes, giving rise to the observed Methyl mercury: very toxic, highly selective for lipid-rich medium such basophilic stippling of red blood cells as brain shainlee periabras 4  MOLYBDENUM GENETIC ZINC DEFICIENCY An essential trace element which is a component xanthine ACRODERMATITIS ENTEROPATHICA oxidase, aldehyde oxidase and sulfite oxidase rare autosomal recessive disorder with impaired intestinal Binds molybdenum in the form of a cofactor called molybdopterin absorption and transport of zinc Grains, nuts, and legumes such as peas, lentils, and beans are SYMPTOMS INCLUDE: good sources. - hyperpigmented skin lesions, pustular and bullous Can cross the placental barrier and increase intake of dermatitis, alopecia, growth retardation, diarrhea, secondary molybdenum in the diet of the mother which can increase its level infection, irritability, lethargy, and depression in the neonate’s liver ZINC TOXICITY SELENIUM Inhalation of zinc oxide fumes is the most common cause of toxic element in the 1930s, carcinogen in 1940s, essential METAL FUME FEVER element in 1950s and anticarcinogen since 1960s Chronic oral zinc supplementation interferes with copper constituent of glutathione peroxidase, associated with vit E in its absorption and may cause copper deficiency forming the basis functions which is important in defense against oxidative stress for using zinc to treat Wilson's disease. Also involved in the metabolism of thyroid hormones deiodinase, thioredoxin reductase II. ANALYTICAL METHODOLOGIES Deficiency is associated with cardiomyopathy, skeletal muscle ANALYTICAL CONSIDERATIONS weakness and osteoarthritis Assessment of trace mineral status is difficult and requires - Keshan disease - an endemic cardiomyopathy that affects specialized analytical instruments (e.g, AAS, AES) mostly children and child-bearing age in certain Serum measurements are complicated by associated disease areas in China is associated w/ selenium def. states that affect levels of circulating binding proteins (e.g., - Kashin-Beck disease - endemic osteoarthritis that occurs albumin) during adolescent and preadolescent years, Dx is dependent on high degree of suspicion, careful inspection another disease linked to low selenium levels in for signs and symptoms, thorough understanding of predisposing Norther China, North Korea and Eastern Siberia. causes and resolution of symptoms with therapeutic trial. Toxicity: hair loss, garlic breath, irritability, mild nerve damage, Assessment of trace element status requires measurement of and nail damage either the CONCENTRATION in accessible tissues (hair, nails) and body fluids (serum, urine) or the ACTIVITY OF A TRACE ZINC ELEMENT–dependent enzyme. Second only to iron in importance as an essential trace element Hair and nail clippings should be collected with care and washed The most common catalytic metal ion in the cytoplasm of cells to avoid surface contamination. Main biochemical role of zinc is seen in its influence on the activity Assays in blood, serum, or urine usually reflect the current of more than 300 enzymes in classes such as oxidoreductases, nutriture or RECENT exposure tranferases, lyases, isomerases and lipases. Hair, fingernail, or toenail analyses provide an assessment of Zinc is ubiquitous in food: Oysters, Shellfish and meats. CHRONIC exposure Nutritional zinc deficiency is fairly common prevalent despite There are no particularly good indicators for the determination of the wide availability of zinc in foods trace element dietary status because of poor correlation with total Conct in body organs: Skeletal muscle: 60% | Bone: 30% body stores. only definitive test of human trace mineral element deficiency is: ZINC-CONTAINING METALLOENZYMES - clinical response to controlled supplementation Carbonic anhydrase, Alkaline phosphatase RNA and DNA polymerases, Reverse transcriptase SPECIMEN COLLECTION & PROCESSING Thymidine kinase, Caboxypeptidases Trace elements must be analyzed with considerable care Alcohol dehydrogenase, Superoxide dismutase Clean room techniques and ultra-pure reagents must be used. - Type I water ACQUIRED ZINC DEFICIENCY Reference materials and strict quality control are requisite with Zinc deficiency produces a syndrome of: each assay run to ensure analytic accuracy. - growth retardation, male hypogonadism, skin changes Special collection and handling are necessary. - mental lethargy, hepatosplenomegaly, IDA - They are ubiquitous - reduced taste acuity, geophagia (eating clay). - Materials of biological devices (e.g., needles, syringes, Encountered most often in male children in Iran and Egypt as a stoppers) can readily contaminate a sample result of a low-zinc diet and a high fiber content that decrease o Remedy: use trace element–free syringes available zinc for absorption o Evacuated tubes with fitted siliconized needles, acid- Zinc deficiency has been reported from Turkey, Portugal, washed glassware Morocco, and Yugoslavia o Use standard reference materials with certified values Middle East: people frequently eat unleavened bread that is high in phytate. shainlee periabras 5  PRECAUTIONARY MEASURES ATOMIC EMISSION SPECTROSCOPY (AES) Control of laboratory environment THREE COMPONENTS: Trace element laboratory must be placed in a separate room 1. Source- Flame or inductively coupled plasma incorporating rigorous contamination control measures - Liquid sample is converted into aerosol and delivered into - sticky mats at doors, non-shedding ceiling tiles the source where sufficient energy will excite the atoms - carefully controlled air flow 2. Monochromator- Isolates specific wavelengths - disposable booties worn over shoes 3. Detector- Measures the intensity of radiation - particulate monitoring equipment - Photographic film (obsolete), replaced by photomultipliers and array-based detector systems CAUSES OF DEFICIENCY Decreased intake→ nutritional deficiency ELEMENTAL SPECIATION Total parenteral nutrition→ inadequate supplementation Toxicity of the elements may depend on their chemical form Increased utilization→ increased catabolism - EXAMPLE: Arsenic Interactions between trace elements (zinc, copper) or with other o Arsenobetaine: nontoxic form of arsenic nutrients (zinc, vitamin C) o Methylated forms: intermediate in toxicity Zinc interferes with copper absorption resulting in copper o Inorganic arsenic (As[V], As[III]): highly toxic deficiency and anemia Hyphenated techniques Increased excretion - Allows determination of elemental species DISEASE STATES- insufficient intestinal absorption - Combination of two or more complementary analytical - acquired: malabsoprtion syndromes, intestinal resection techniques - genetic: mutation resulting in the lack of protein needed to absorb the element o Menkes’ kinky hair syndrome (copper) o Congenital atransferrinemia (iron) o Acrodermatitis enteropathica (zinc) o Xanthine & sulfite oxidase deficiencies (molybdenum) LAB METHODOLOGIES ATOMIC ABSORPTION SPECTROMETRY most commonly used for trace and toxic metal analysis FLAME AAS: Uses flame - used in the measurement of copper, iron, zinc - LOQ (limit of quantitation) - parts per million (mg/L) GFAAS: Uses graphite furnace - used in the measurement of selenium, cadmium, lead most widely used instrument for clinical trace element analysis in biological samples Analytic procedure for the quantitative determination of elements through the absorption of optical radiation by FREE ATOMS on the gas phase FOUR IMPORTANT COMPONENTS 1. Radiation (light) source - emits the spectrum of the analyte element. 2. Atomizer - in which the atoms of the element of interest in the sample are formed. 3. Monochromator - for the spectral dispersion of the radiation & separation of analytical line from other radiation. 4. Detector INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY (ICP-MS) highly sensitive and specific method for measurement of multiple trace elements in a single run uses ionized gas (argon) to excite the atoms uses internal standard Yttrium shainlee periabras 6