Clin Chem

• Clinical Chemistry


  The systematic study of biochemical processes associated with health & disease & the measurement of constituents in body fluids or tissues to facilitate diagnosis of disease
• Purpose & function of laboratorians through clinical pathology & laboratory medicine

  • Confirming or rejecting a diagnosis
  • Providing guidelines in patient management
  • Establishing a prognosis
  • Detecting disease through case finding or screening
  • Monitoring follow-up therapy
• Scope of Clinical Chemistry

  • Anatomy & Physiology
  • Computers
  • Analytical Chemistry
  • Pharmacology
  • Instrumentation
  • Toxicology
  • Biochemistry
  • Cell Biology & Genetics
  • Endocrinology
  • Immunology
• It is much easier to detect a MALFUNCTION than to elucidate or document the cause
• Causes of cell malfunction

  • Destruction by trauma or by invasive agents
  • Genetic deficiency of a vital enzyme
  • Insufficient supply of one or more essential nutrients
  • Insufficient blood supply
  • Insufficient oxygen supply
  • Malignancy
  • Accumulation of waste products
  • Failure of a control system
  • Defect in the cellular recognition of certain signals
• Point-of-care Testing (POCT)


  Also known as near-patient testing, alternate-site testing or patient-focused testing
• Point-of-care Testing


  • Used in emergency dept., operating suites, clinics, health maintenance organization (HMO), physicians offices & nursing homes
  • Addresses acute patient needs
  • Instrumentation includes portable chemistry analyzers, glucometers, BG Analyzers, hemoglobin meters & coagulation testing
• Specimens or samples are analyzed while substances in them are measured or quantitated
• Types of Substances

  • Substances which are normally present to sustain life (e.g. glucose, proteins, lipids, vitamins, hormones, electrolytes, ABG)
  • Substances which are excreted waste products of metabolism (e.g. NPNs and bilirubin)
  • Substances released from cells as a result of cell damage & abnormal permeability or abnormal cellular proliferation (e.g. enzymes such as LD, ALT, AST, CK, AMS, GGT, ALP & ACP; ferritin)
  • Substances foreign to the body (e.g. antibodies, substances of abuse, poisons, and therapeutic drugs)
• Laboratory Wares

  • Glasswares
  • Plasticwares
• Glasswares


  • Breakable
  • Reusable
  • Ideal for acidic solutions
  • High thermal & corrosion resistance
  • Good optical properties
  • Low cost
• Plasticwares


  • Disposable
  • Highly shock proof; shatterproof
  • Ideal for alkaline solutions
  • Relatively inert
  • Flexible
  • For cryogenic experiments
• 5 General Types of Glass

  • High thermal resistant glass
  • Corex
  • Vycor
  • High silica glass
  • Glass with high resistance to alkalies
  • Low actinic glass
  • Standard flint glass
• High thermal resistant glass


  • Borosilicate glass with low alkali content
  • Resists heat, corrosion and thermal shock
  • Most common are Pyrex, Kimax and Exax
• Corex


  • 6x stronger than borosilicate glass
  • Alumina-silicate glass
  • Better able to resist clouding due to alkali or scratching
  • Ideal for higher temperature thermometers, graduated cylinders and centrifuge tubes
• Vycor


  • Recommended for use in application involving high temperature and drastic heat shock and extreme chemical treatment with acids and dilute alkalies
  • Heatable to 900oC and withstand downshock from 900oC to ice water
  • Ideal for ashing and ignition techniques
• High silica glass


  • 96% silica content comparable to fused quartz in its thermal endurance, chemical stability and electrical characteristics
  • Radiation resistant, good optical qualities and temperature capabilities
  • Ideal for high precision analytical work and can also be used for optical reflectors and mirrors
• Glass with high resistance to alkalies

  • Boron-free glassware for strong alkali solutions and digestion with strong alkalies
  • Less thermal resistant than borosilicate glass
  • Known as soft glass
• Low actinic glass


  • Amber or red-colored to reduce the amount of light passing through the substance within the glassware
  • Highly protective laboratory glassware for handling heat-labile substances in the 300-500nm range (bilirubin, carotene and vitamin A)
• Standard flint glass


  • Soda-lime glass which is composed of a mixture of oxides of Si, Ca and Na
  • Lowest in cost and readily fabricated
  • Poorly resistant to high temperature and sudden changes in temperature
  • Easy to melt and shape thus used as reagent bottles and disposable laboratory glasswares
  • Releases alkali into the pipetted liquid
• Plastics


  • Polyolefins (polyethylenes, polypropylenes)
  • Polycarbonate resin
  • Tygon
  • Teflon fluorocarbon resins
• Polyolefins (polyethylenes, polypropylenes)


  • Unique group of resins with relatively inert chemical properties
  • Unaffected by acids (however, concentrated sulfuric acid slowly attacks polyethylene at RT), alkalies, salt solutions and most aqueous solutions
  • Aromatic, aliphatic and chlorinated hydrocarbons cause moderate swelling at RT
  • Organic acids, essential oils and halogens slowly penetrate these plastics
  • Strong oxidizing agents attack this group at elevated temperatures only
  • Polypropylene is more expensive than polyethylene therefore the latter is used in most disposable plastic wares
  • Polypropylene is sterilizable however it absorbs pigment and tends to become discolored
• Polycarbonate resin


  • Twice as strong as polypropylene (from –100oC to +160oC)
  • Chemical resistance is not as wide as the polyolefins
  • Unsuitable for use with bases as amines, ammonia and alkalies also oxidizing agents
  • Glass-clear and shatterproof
  • Ideal for centrifuge tubes and graduated cylinders
• Tygon


  • Nontoxic, clear plastic of modified PVC (polyvinylchloride)
  • Used extensively for the manufacture of ACA (automated clinical analyzer) tubings
  • Flexible and used to handle most chemicals
  • Can be steam-autoclaved or chemically sterilized
  • Tubing is soft and flexible and quickly slips over tubulatures but gripping tightly on glass or metals
• Teflon fluorocarbon resins


  • Almost chemically inert with high corrosin resistance at extreme temperatures
  • For cryogenic experiments and work at high temperatures over extended periods (-270oC to +255oC)
  • Pure translucent white and inert
  • Easy to clean and fast drying but it can be scratched and misshaped
• Large Volume Pipets - Volumetric or Transfer Pipet


  • Designed to deliver (TD) a fixed volume of liquid
  • Consists of a cylindrical bulb joined at both ends to narrower glass tubing
  • Calibration mark is etched around the upper suction tube
  • Lower delivery tube is drawn out to a fine tip
  • Used for accurate measurements of aliquots of nonviscous samples, filtrates and standard solutions
• Large Volume Pipets - Ostwald-Folin Pipet


  • Similar to volumetric pipet but have their bulb closer to the delivery tip
  • Used for measuring viscous fluids as blood or serum
  • Has an etched ring near the mouthpiece (blowout pipet)
  • Blown out only when the fluid has drained to the last drop in the delivery tip
• Large Volume Pipets - Graduated or Measuring Pipets


  • Plain, narrow tube drawn out to a tip
  • Graduated uniformly along its length
  • Two types which are calibrated for delivery are available: Mohr pipet (calibrated between two marks on the stem) and Serological pipet (has graduation marks down on the tip and blown out to deliver the entire volume of the pipet if etched ring or double rings are evident near the mouth of the pipet)
  • Intended for the delivery of predetermined volumes
  • Principally used for the measurements of reagents and are not generally considered accurate enough for measuring samples and standards
  • Serological pipets have large orifice than the Mohr pipet and thus drain faster
• Micropipets

  • Sahli (TC)
  • Kirk (TC)
  • Lang-Levy (TD/ TC)
  • Overflow (TC)
  • Capillary (TC)
  • Sanz Pipet (TD=TC)
  • Unopette (TC)
  • Semiautomatic pipet Eppendorf (TD/TC)
• Analytical Reagent (AR) or ACS


  Chemicals of very high purity, as established, used in most analytical laboratory procedures and making up reagents for spectrophotometry, chromatography, trace metal analysis, atomic absorption spectrophotometry (AAS), fluorometry and standardization procedures
• Primary standard (PS)


  A chemical that is the highest purity and can be measured directly to produce a substance of exact known concentration
• Secondary standard


  A substance of lower purity whose concentration is determined by comparison to a primary standard
• Reagent grade water (RGW)


  Water suitable for reagent and standard preparation, including distilled water and deionized water
• Type I Reagent Grade Water


  • Used for procedures that require maximum water purity such as preparations of standard solutions, ultramicro chemical analysis, measurement of nanogram or subnanogram concentration and tissue or cell culture (or both)
• Type II Reagent Grade Water


  • Used in most laboratory determination in chemistry, hematology, microbiology, immunology and other chemical laboratory areas
• Type III Reagent Grade Water


  • Used in most qualitative measurement / examinations, most procedures in urinalysis, parasitology and histology, washing glasswares and procedures not requiring Type I or Type II water
• Carbon dioxide-free water


  Obtained by boiling Type II water, used when carbon dioxide, ammonia and oxygen may affect analysis
• Relative Centrifugal Force (RCF)


  Obtained by using a nomogram or by using the formula: RCF = 1.118 x 10-5 x r x rpm2, where r is the radius in cm. between the axis of rotation and the center of the centrifuge tube, and rpm is the speed in revolutions per minute
• Centrifuge safety


  • CAP recommends cleaning of any spills or debris such as blood, glass and others daily; checking of the timer, brushes and speed every three months
  • Speed of the centrifuge is checked using the tachometer or strobe light
• Safety equipment required in laboratories

  • Safety showers
  • Eyewash stations
  • Fire extinguishers
  • Fire blankets
  • Spill kits
  • First aid supplies