Quiz

• Tests for Pancreatic Function

  • Cholecystokinin Test
  • Fecal Fat Analysis
  • Fecal Enzymes
  • Sweat Electrolyte Testing
  • Serum Enzymes
• Cholecystokinin (CCK) Test

  1. Intubation of duodenum without contamination by gastric fluid

  2. Pancreatic secretion stimulated by intravenously administered secretin

  3. CCK administration

  4. Pancreatic secretions collected for 30, 60, or 80 minutes

  5. pH, secretory rate, enzyme activities, and amount of bicarbonate determined
• Normal bicarbonate excretion

  • 15 mmol/L for men
  • 12 mmol/L for women
• Sources of fecal lipids

  • Unabsorbed ingested lipids
  • Lipids excreted into the intestine
  • Cells shed into the intestine
  • Metabolism of intestinal bacteria
• Normal fecal lipid composition

  • 60% fatty acids
  • 30% sterols, higher alcohols, and carotenoids
  • 10% triglycerides
  • Small amounts of cholesterol and phospholipids
• Qualitative screening tests for fecal fat

  Use fat-soluble stains to visualize lipid droplets (Sudan III, Sudan IV, Oil Red O, Nile blue sulfate)
• Sudan staining for fecal fat

  1. Sudan III/IV stains triglycerides and other lipids yellow-orange to red

  2. Free fatty acids do not stain appreciably unless heated in 36% acetic acid

  3. Detection of meat fibers by staining with eosin
• Normal feces

  40-50 (1-5mm) neutral lipid droplets per high-power microscope field
• Steatorrhea

  • Increased number and size of stained droplets
  • Often has fat globules in 50–100mm range
  • Fatty assessment >100 stained small droplets with meat fiber is expected
• Quantitative fecal fat analysis

  1. 72-hour stool collection

  2. Gravimetric method: Emulsify entire fecal specimen in water, convert fatty acid soaps to free fatty acids, extract with petroleum ether and ethanol, evaporate and weigh lipid residue
• Reference range for fecal fat (adults)

  1. 7g per 24hrs
• Fecal elastase-1

  • Chymotrypsin-like enzyme secreted by the pancreas, remains stable in feces
  • Reference range: >200 ug/g
  • 100-200 ug/g suggests moderate pancreatic insufficiency
  • Less than 100 ug/g suggests severe pancreatic insufficiency
• Sweat electrolyte testing

  • Measures chloride concentration in sweat
  • Cystic fibrosis patients have reduced ability to resorb chloride from sweat, resulting in significantly elevated sodium and chloride concentrations
• Sweat collection by iontophoresis

  Pilocarpine is administered by iontophoresis to induce sweating, usually on the inside of the forearm
• Sweat chloride concentration diagnostic of cystic fibrosis

  Greater than 60 mmol/L in children
• Serum enzymes for pancreatic function

  • Lipase is more sensitive and specific than amylase
  • Lipase increases within 24 hours in acute pancreatitis and persists for 8-14 days
  • Amylase increases within 3-6 hours, peaks at 24 hours, and returns to normal within 3-5 days
• Conditions with significantly increased amylase

  • Mumps
  • Cholecystitis
  • Hepatitis
  • Cirrhosis
  • Ruptured ectopic pregnancy
  • Macroamylasemia
• Conditions with significantly increased lipase

  • Bone fractures
  • Fat embolism
• Essential trace elements


  Deficiency impairs a biochemical or functional process, and replacement corrects the impairment
• Nonessential trace elements


  Elements of medical interest primarily because they are toxic
• Trace element analysis

  Commonly uses atomic absorption spectrometry, either with flame (FAAS) or graphite furnace (GFAAS)
• Amylase


  Significantly increased in mumps, cholecystitis, hepatitis, cirrhosis, ruptured ectopic pregnancy, macroamylasemia
• Lipase


  Significantly increased in bone fractures, fat embolism
• Trace elements

  Essential element - if a deficiency impairs a biochemical or functional process and replacement of the element corrects this impairment
• Trace element deficiency

  Decreased intake, impaired absorption, increased excretion, and genetic abnormalities could result in deficiency
• Non-essential elements


  Elements are of medical interest primarily because many of them are toxic
• Cofactors

  Metalloenzyme, metalloprotein
• Instrumentation for trace and toxic metal analysis

  Atomic absorption spectrometer, either with flame (FAAS) or flameless (graphite furnace, GAAS) atomization
• Sample collection and processing

  1. Use special collection tubes

  2. Do not insert a pipette into the specimen, transfer by pouring

  3. Do not ream the serum with a wooden applicator stick

  4. Submit hair and nails specimens in separate containers
• Atomic emission spectroscopy (AES)

  • Useful for some elements, particularly if used in the form of inductively coupled plasma atomic emission spectroscopy (ICP-AES) for atomization and excitation
  • 3 most important components: source, wavelength-selecting device, detector
• Atomic absorption spectroscopy (AAS)


  1. Quantitative determination of elements through the absorption of optical radiation by free atoms in the gas phase

  2. 4 most important components: radiation source, atomizer, monochromator, detector

  
• Inductively coupled plasma spectrometry (ICP-MS)

  Sensitive analytical technique for elemental analysis, measures the mass-to-charge ratio

  
• Quadrupole mass spectrometers

  Typical mass spectrometer used for ICP-MS, with an analyzer consisting of four parallel conducting rods

  
• High resolution mass spectrometers

  Usually "double focusing sector field" instruments, separate ions of different m/z values via deflection in a magnetic field

  
• Interferences

  Classified as spectroscopic (result from a spectral overlap) or nonspectroscopic (matrix interferences)

  
• Aluminum

  • Silver-white, crystalline, ductile metal, most abundant metal in the earth's crust (-8%), combined with other elements such as oxygen, silicon, and fluorine, applicable to a wide variety of industrial and household uses
• Absorption, transport, and excretion of aluminum


  1. Human organism can absorb aluminum and its compounds orally, through inhalation

  2. Approximately 1.5% to 2% of inhaled and 0.01% to 5% of ingested aluminum are absorbed

  3. In plasma, aluminum is bound to carrier proteins such as transferrin

  4. Aluminum binds to various ligands in the blood and distributes to every organ, with highest concentrations ultimately found in bone and lung tissues

  5. Urine accounts for 95% of aluminum excretion, with 2% eliminated in the bile
• Health effects and toxicity of aluminum

  • Administration of aluminum to experimental animals is known to produce encephalopathy similar to that seen in Alzheimer's disease in humans
  • Workers who breathe large amounts of aluminum dusts may develop lung problems
  • Signs and symptoms of aluminum toxicity include encephalopathy, osteomalacia or aplastic bone disease, proximal myopathy, increased risk of infection, microcytic anemia, increased left ventricular mass, decreased myocardial function
• Laboratory evaluation of aluminum

  1. Measured using ICP-MS and may also be measured by GFAAS

  2. Metal-free collection tubes must be used for samples intended for aluminum measurement

  3. Urine and serum levels are used for screening
• Reference range for aluminum

  0-6 ng/mL