CLSChem 05 - Carbs and Diabetes Nutrition Proteins Tumor Markers

  1. What are the monosaccharides and disaccharides w/ components?
    • Glucose, fructose, galactose
    • sucrose (glucose + fructose)
    • lactose (glucose + galactose)
    • maltose (glucose + glucose)
    • *NOTE - absorbed as monos
  2. BASICALLY describe the major metabolic pathways (glycolysis, tricarboxylic acid cycle, glycogenesis, pentose phosphase/HMP shunt, glycogenolysis, gluconeogenesis)
    • glycolysis: anaerobic, glucose -> pyruvate <-> lactate
    • TCA: aerobic, glucose -> pyruvate + CO2 + H2O + ATP
    • glycogenesis: glucose -> glycogen
    • pentose phosphase/HMP shunt: glucose -> ribose + CO2 + NADPH
    • glycogenolysis: glycogen -> glucose
    • gluconeogenesis: noncarbohydrates (AA, lipids) -> glucose
  3. Insulin - synthesis/production, effect, testing
    • Secreted by pancreated beta cells in response to increased blood glucose
    • proinsulin -> insulin + C-peptide
    • facilitates uptake of glucose into cells
    • inc glyogenesis, glycolysis, and lipogenesis
    • inhib glycogenolysis
    • only hormone to lower blood glucose
    • Testing primarily concerned w/ hypoglycemia
    • Testing interpretation complicated
    • C-peptide testing may be a better substitute
  4. What is C-peptide and why might it be tested?
    • proinsuling -> insulin + C-Peptide
    • Better substitute for insulin testing
    • evaluating insulin-induced hypoglycemia
    • endogenous insulin: elevated C-peptide (normal synth)
    • exogenous insulin: normal/low C-peptide (eg artificial intake)
  5. Glucagon - synthesis/production, effect, testing
    • Secreted by pacreatic alpha cells in response to low blood glucose
    • stimulates glycogenolysis and gluconeogenesis in liver
    • enhances ketogenesis
    • raises blood glucose
    • rarely measured
  6. How do cortisol, epinephrine, and growth hormone interact with blood glucose?
    All RAISE blood glucose
  7. What is the problem with peroxidase steps in testing?
    Interference with bilirubin, hgb, and vitamin C
  8. What are the intervals for glucose. What is a challenge of processing?
    • Ref: 70-100mg/dL (fasting)
    • Hypo (crit): <50mg/dL, <30 life threatening
    • Hyper (crit): >500mg/dL
    • Levels decrease 5-7%/hr in uncentrifuged blood (higher w/ high WBC)
    • Oxalate tubes not effective for 1-2 hours
  9. 3 causes of hypoglycemia
    • Reactive: overshoot following a meal
    • Decreased production: severe hepatic dysfunction, Addison's disease
    • Increased uptake/utilization: over-administration of insulin (dec C-peptide), insulin-producing tumors (inc C-peptide)
  10. BASIC info for DM1, DM2, and GDM
    • DM1: insulin deficiency is primary issue (autoimmune against beta cells)
    • requires insulin replacement
    • 5-10% of all cases
    • DM2: insulin resistance is primary issue
    • not as 
    • 90% of all cases
    • GDM: insulin resistance is primary issue
    • onset/diagnosis during pregnancy
    • *macrosomia and hypoglycemia in baby (response to hyperglycemic mother)
  11. Acute vs chronic complications of DM
    • Acute: glucose deficit within cells (glucose can't get in)
    • hyperosmolar hyperglycemic state (HHS)
    • chronic: glucose excess over time causes damag
    • acute leads to diabetic ketoacidosis (lipolysis, acetoacetate formation)
  12. What are the ketone bodies?  Describe the testing
    • Acetoacetate, Acetone, beta-hydroxybutyrate
    • Acetest/ketostix: urine/serum dipsticks
    • BHB enzymatic: quant and spp, automated
    • AcOAc and BHB normally low, ~equal
    • Excess NADH from lipolysis pushes >70% to BHB
    • *NOTE - BHB dec and AcOAc inc during recovery
  13. How do you diagnose DM?
    • Hgb A1C ≥6.5% (not using POCT)
    • Fasting plasma glucose ≥126mg/dL
    • 2hr plasma glucose ≥200mg/dL during oral glucose tolerance test
    • Random plasma glucose ≥200mg/dL WITH symptoms of hyperglycemia
  14. Describe the oral glucose tolerance test (GTT) and its interpretation
    • For fasting, ambulatory, non-preggos
    • Given 75gm glucose
    • Diabetes: fasting sample ≥126mg/dL or 2hr sample ≥200gm/dL
    • Impaired glucose tolereance: 2 hr 140-199mg/dL
    • Impaired fasting glucose: 101-125mg/dL ("prediabetes")
  15. Describe the process to diagnose GDM
    • 50g 1hr GTT (non-fasting)
    • if ≥140mg/dl then...
    • 100g 3hr fasting GGT
    • exceeding any 2/4 cutoffs over a 3 hour period (including fasting draw) signifies GDM
  16. What is Hgb A1 w/ variants.  Compare/contrast the 3 testing methods
    • Hgb A1: glycated Hgb (A1a1, A1a2, A1b, A1c)
    • A1c has an attached glucose (relevant to blood glucose levels over past 120 days)
    • Normally 4-5% of HgbA
    • 80% of all Hgbs
    • Ion exchange chrom: separates based on charge change when glucose binds
    • potential interference w/ some alt Hgbs
    • Immunoassay: Ab against the glycopeptide Ag
    • may require manual dilution
    • potential interference w/ some alt Hgbs
    • Affinity chrom: only binds glycated Hgb
    • binds all glycated Hgb, calculation must reduce value to accurate A1C value
    • Typical POC method
    • *note - decreased RBC life underestimates the true value
  17. What is fructosamine?
    • Generic name for glycated plasma proteins (ketoamine adducts)
    • These can be measured, and indicated a more narrow timeframe than A1c
    • Useful for hemoglobinopathies, anemia, and GDM
  18. What is the purpose of the microalbumin test?
    • Demonstrates minimal (initial) glomerular damage from diabetes
    • *note- small amounts of albumin in urine, not detected by dipstick
  19. How is iron transported and stored? (3 subs + general info)
    • Transferrin: binds 2x Fe3+ ions in serum
    • in excess, normally 20-50% saturation
    • special receptor for tissue uptake
    • Ferratin: binds up to 4500 Fe3+ in most cells
    • Readily mobilized if needed
    • Hemosiderin: insoluble complex derived from ferritin
    • releases iron less readily than ferratin
  20. Serum iron measurement test basics
    • Fe3+ is released from binding proteins (not heme/Hgb) by acidification
    • Reducing agent (vit c?) = Fe3+ -> Fe2+
    • binds to a dye and is measured
    • tests should include iron-binding capacity
    • iron shows diurnal variation (highest in AM)
  21. transferrin measurement test basics
    • Direct: immunoassay against transferrin
    • TIBC: total iron binding capacity
    • add excess Fe3+ to sample (equilibrate)
    • complex non-bound iron and separate it
    • measure Trf-bound iron
    • UIBC: unsaturated iron binding capacity
    • add excess Fe3+ to sample (equilibrate)
    • measure unbound iron only
    • *NOTE - tferrin sat = Fe/TIBC x 100%
  22. Ferritin test basics
    • Measured directly by immunoassay (sandwich)
    • ferritin is proportional to stored iron levels
    • *NOTE - acute phase reactant! Inflammation will artificial inflate the result.
  23. 3 stages of iron deficiency anemia
    • Iron depletion: depletion of stores (ferritin decrease)
    • normal serum iron and TIBC
    • No anemia or abnormal RBCs
    • Iron-deficient erythropoiesis: decreased iron for erythropoeisis (stores depleted)
    • decreased ferratin, serum iron, transferrin saturation
    • increased TIBC, transferrin
    • No anemia
    • slightly microcytic RBCs, increased RDW
    • Iron deficiency anemia: Decrease in ferritin, iron, transferrin saturation
    • Increase in TIBC, transferrin
    • decrease in Hgb, MCV, MCH, MCHC
    • increased RDW
    • microcytic, hypochromic anemia
  24. What are porphyrias?  How might they manifest?
    • Rare disorders of partial enzyme deficiency for creation of porphyrin rings (heme, cytochromes)
    • *NOTE - could not be full deficiency or life could not exist (cytochromes)
    • buildup of ALA since heme does not inhibit -> symptoms
    • Acute neurologic presentations
    • Chronic photosensitivity
  25. Copper - function, transport, deficiency symptoms, excess symptoms
    • function: enzyme cofactor
    • transport: bound to ceruloplasmin (α2 globulin)
    • deficiency: microcytic, hypochromic anemia
    • neutropenia
    • excess: Wilson's disease (copper deposition in tissues, esp liver/brain)
    • decreased ceruloplasmin and serum Cu, with elevated urine Cu
  26. compare/contrast Fat soluble vitamins vs water soluble vitamins
    • Fat soluble: A, D, E, K
    • readily stored in body, deficiency develops slowly
    • Water soluble: Thiamine (B1), Niacin (B3), Pyridoxine (B6), Cobalamin (B12), Ascorbic acid (C)
    • Not stored (except B12), require continuous intake
    • Toxicity uncommon (except B6)
  27. Vitamin B12 - structure, absorption/storage, testing, deficiency symptoms
    • AKA Cobalamin
    • structure: ring with Co+ (not Fe) coordination atom
    • abs/stor: absorption requires low pH to dissociate B12 from food and intrinsic factor to absorb
    • stored in liver (5 year supply)
    • testing: immunoassay OR intrinsic factor binding assay
    • def: megaloblastic anemia, irreversible neuropathy
    • treat w/ intramuscular injections if necessary
  28. Folate: what is the problem?
    • Serum folate can be skewed by a single salad before the test
    • Not representative of that actual picture
    • RBC better reflects body stores
  29. Why does macronutrition revolve around protein?
    • We cannot synthesize essential AA
    • We do not recycle nitrogen well
  30. What is nitrogen balance and what is the best marker?
    • Reltionship of nitrogen intake vs excretion
    • Prealbumin is the most common marker due to it's fast half life (2 days)
  31. Describe a basic electrophoresis setup (charges, pH, application, etc)
    • Cathode: negative
    • Anode: positive
    • gel pH 8.6 (makes all proteins neg charge)
    • application of sample at cathode (moves toward anode)
  32. What is electroendosmosis?
    • A net solvent flow toward the cathode that occurs during electrophoresis
    • Uncharged/low charge proteins will migrate toward cathode w/ the solvent (charged proteins migrate toward anode)
  33. How is isoelectric focusing different from other electrophoretic methods?
    • Isoelectric focsing has a pH gradient
    • Proteins STOP migrating when they reach their isoelectric point (pI)
  34. What is hypergammaglobulinemia? Categories w/ examples
    • Polyclonal: increase in multiple Igs
    • Monoclonal: single Ig (paraprotein or M-protein)
    • Multiple myeloma (plasma cell malignancy)
    • Lymphoid tumors
    • Waldenstrom macroglobulinemia (IgM, bence-joyce)
    • Heavy chain disease
    • Serum free light chains (inc levels or abn ratio)
    • *NOTE - malig can also be non-secretory (no Ig production)
  35. What are cryoglobulins and why might they cause testing trouble?  How can you test for them?
    • Igs that reversibly ppt at >37C
    • They can ppt in analyzers causing performance issues
    • Test via collect and cfuge @37, incubate @4 for several days, reinc @37 and see what redissolves
    • NOTE - related to monoclonal gamm.
  36. What are the three REVERSE acute phase reactants?
    Albumin, Pre-albumin, and transferrin
  37. IEP vs IFE
    • Immunoelectrophoresis: very difficult/confusing
    • antisera in adjacent trophs with sample innoc between
    • Looking for thickening/arc at zone of equivalent (ppt sample)
    • Immunofixation: G, A, M, κ, λ
    • 6 lanes of sample are electrophoresed
    • Addition of antisera to 5 lanes (#6 is ref)
    • Look for abnormalities (heavy + light?)
Card Set
CLSChem 05 - Carbs and Diabetes Nutrition Proteins Tumor Markers
CLSChem 05 - Carbs and Diabetes, Nutrition, Proteins, Tumor Markers