Clinical Chemistry 2 - Trace Elements PDF

CLINICAL CHEMISTRY 2 FINALS Lecture - Trace Elements...

CLINICAL CHEMISTRY 2 FINALS Lecture - Trace Elements L.N.L RMT, MD TRACE AND TOXIC ELEMENTS SAMPLE COLLECTION AND PROCESSING Essential element Special collection tubes (Royal Blue stopper with or without EDTA additive) should be used. It corrects the impairment if a deficiency impairs a biochemical or functional process. Do not insert pipette into specimen instead, transfer by pouring. Metalloenzyme Do not ream serum with a wooden applicator stick. Essential trace elements are often associated with an enzyme. When submitting hair and nails specimens, submit in separate containers to avoid Metalloprotein contamination. Essential trace elements are often associated with a protein. Dietary Requirement for Nutrients ATOMIC EMISSION SPECTROSCOPY According to WHO, this is the smallest amount of nutrients needed to maintain optimal Has 3 most important components: function and health. 1. Source, in which the sample is atomized at a sufficient temperature to produce an Nonessential elements excited-state species. Any element that is not considered essential. 2. Wavelength-selecting device (Monochromator), for the spectral dispersion of the Nonessential trace elements are of medical interest primarily because many of them are radiation and separation of the analytical line from other radiation. toxic 3. Detector which permits measurement of radiation intensity. Trace Element mg/dL conc. ATOMIC ABSORPTION SPECTROSCOPY Ultratrace Element An analytical procedure for the quantitative determination of elements through the ug/dL conc. absorption of optical radiation by free atoms in the gas phase. Governed by Beer-Lambert Law INSTRUMENTATION AND METHODS Has 4 most important components: Atomic Absorption Spectrometer (AAS) 1. Radiation (light) source, which emits the spectrum of the analyte element. For many years, the most commonly used instrumentation for trace and toxic metal analysis - Most common sources: has been the atomic absorption spectrometer, either with flame (FAAS) or flameless (i.e., a. Flame (FAAS) graphite furnace, GFAAS) atomization. b. Graphite furnace (GFAAS) a.k.a flameless or electrothermal AAS Emission Spectrum allows for measurements of both liquid and solid samples. Composed of a series of very narrow peaks (sometimes known as “lines”), with each line at a 2. Atomizer, in which the atoms of the element of interest in the sample are formed. different wavelength and matched to a specific transition. - Graphite tubes are the most commonly used atomizers in flameless AAS. Inductively Coupled Plasma Mass Spectrometry (ICP-MS) 3. Monochromator, for the spectral dispersion of the radiation and separation of the Now more widely used because of its increased sensitivity, wide range of elements covered, analytical line from other radiation. and relative freedom from interferences. 4. Detector permitting measurement of radiation intensity. Atomic Emission Spectroscopy A liquid sample, containing element(s) of interest, is converted into an aerosol and delivered INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY (ICP-MS) into the source, where it receives energy sufficient to emit radiation. Plasma in ICP refers to an ionized gas (typically argon), in which a certain proportion of Atomic Absorption Spectroscopy electrons are free. An analytical procedure for the quantitative determination of elements through the Components: absorption of optical radiation by free atoms in the gas phase. 1. Ion source 2. Mass analyzer 3. Ion detector  CLINICAL CHEMISTRY 2 FINALS Lecture - Trace Elements L.N.L RMT, MD The argon plasma induced by commercial ICP instruments (both ICP-AES and ICP-MS) For chronic arsenic exposure: dermatologic, cardiovascular, CNS, hepatic, malignancies generates temperatures ranging from 6000 K to 10,000 K - Chronic arsenic exposure has been shown to cause blackfoot disease, a severe form Several purpose of Argon Plasma: of peripheral vascular disease that leads to gangrenous changes - Dries and then vaporizes the droplets produced by the nebulizer. Characterized by: Mees’ lines, sock and gloves neuropathy - Atomization of any molecular species. Arsenic trioxide - Atoms are thermally ionized, at which point they are ready for introduction into - Odorless, tasteless, and one of the most common poisons in human history. the mass spectrometer. - Lethal dose: 0.12-0.30g - Immediate tx: lavage and use of activated charcoal to reduce arsenic absorption ALUMINUM (Al) - Most effective antidotes: dimercaprol (a.k.a., British anti-Lewisite [BAL]), Silver-white, crystalline, ductile metal. penicillamine, and succimer. Most abundant metal in the earth’s crust (~8%). Always found combined with other elements such as oxygen, silicon, and fluorine. ABSORPTION, TRANSPORT, AND EXCRETION Main route of exposure: SIGNS AND SYMPTOMS OF Al TOXICITY - As-containing food, water and beverage, and inhalation of contaminated air Encephalopathy Organic form Proximal myopathy - Such as arsenocholine and arsenobetaine are commonly found in fish and Increased risk of infection seafood, are considered relatively nontoxic, and are cleared rapidly (1 to 2 days). Occurs in people with renal insufficiencies who are treated by dialysis with Inorganic species aluminum-contaminated solutions or oral agents that contain aluminum - Highly toxic and occur naturally in rocks, soil, and groundwater. - They are also found in many synthetic products, poisons, and industrial processes. CLINICAL MANIFESTATIONS OF Al TOXICITY Methylated species Anemia - Intermediate in toxicity and arise primarily from metabolism of inorganic species, Bone disease but small amounts may arise directly from food. Progressive dementia with increased concentrations of aluminum in the brain LAB EVAL OF As STATUS LAB EVAL OF Al STATUS Primarily measured using ICP-MS, GFAAS, or HGAAS (which only requires the hydride Primarily measured using ICP-MS, GFAAS generation (HG) module) Must use: metal-free collection tubes Spx: urine is the best spx due to short half-life in serum; hair and nails has high affinity Spx: urine or serum binding to keratin Ref. range: 0-6 ng/mL Ref. range: