Chemical and Enzymatic methods Flashcards
Reduction of cupric ions to cuprous ions forming
cuprous oxide in hot alkaline solution by glucose.
Alkaline copper reduction method
Cuprous lons + Phosphomolybdate
= Phosphomolybdic Acid or Phosphomolybdenum Blue
Folin Wu method
Cuprous lons +
Arsenomolybdate
=Arsenomolybdic Acid or Arsenomolybdenum Blue
❑Accurate but labor intensive and difficult to automate
Nelson Somogyi method
Cuprous lons + Neocuproine = Cuprous-Neocuproine Complex (Yellow or Yellow
Orange)
Neocuproine method
Modification of Folin Wu
❑It is used for the detection and quantitation
of reducing substances in body fluids like
blood and urine.
Benedict’s method
stabilizing agents of benedict
tartrate
citrate
❑It involves reduction of a yellow ferricyanide
to a colorless ferrocyanide by glucose
(Inverse Colorimetry).
Hagedorn Jensen
Ortho-toluidine (Dubowski
Method)
❑Glacial HAC heat/AC
Schiff’s base
Condensation method
Acts on glucose but not on other sugars and
not on other reducing substances.
Enzymatic methods
Glucose oxidase method measures:
B-D glucose
Csf
Urine glucose
Glucose + O2→gluconic acid +
H2O2
H2O2 measurement methods:
Trinder’s
Peroxidase
Hydrogen peroxidase measurement methods
Trinder
Peroxidase
initially colorless but when
exposed to O2 becomes orange-brown
Ortho-dianisidine method
It measures rate of oxygen consumption
which is proportional to glucose
concentration.
Polarographic Glucose oxidase
The hydrogen peroxide is prevented from reforming oxygen by adding:
Molybdate
Iodide
Catalase
Ethanol
• It is the most specific glucose method;
reference method.
Hexokinase method
Additives used for specimen in hexokinase
EDTA
heparin
fluoride
oxalate
citrate
Besides form plasma, what ate other samples used in hexokinase?
urine
CSF
serous fluids
Enzyme involved in hexokinase method
Glu-6-PD
Substances responsible for false decreased values in glucose oxidase method
bilirubin
ascorbate
uric acid
glutathione
methyldopa
creatinine
l-cystine
l-dopa
dopamine
citric acid
True or False. Hexokinase method is not affected by the presence of ascorbic acid or uric
acid.
True
true or false. Hexokinase method is not affected by the presence of ascorbic acid or uric
acid
true
❑In this method, glucose is reduced to produce a
chromophore that is measured
spectrophotometrically or an electrical current
Glucose dehydrogenase method
this is added to shorten the time
necessary to reach equilibrium.
mutarotase
• It is effective in reducing the rate of
development of diabetic complications
Dextrostics
❑It is requested during insulin shock and hyperglycemia
ketonic coma.
RBS
It is a measure of overall glucose homeostasis.
❑Requirement: NPO (Non-Per Orem) at least 8 hours
before the test
FBS
❑It measures how well the body metabolizes glucose.
2-Hour PPBS
It is a multiple blood sugar test
It is not generally recommended for routine
clinical use in the diagnosis of diabetes.
GTT
GTT is for diagnosis of:
Gestational diabetes
two methods under OGTT
Janney-Isaacson Method
Exton Rose Method
single dose method
Janney-Isaacson Method
Divided Oral Dose or Double
Dose method
Exton Rose Method
It is used for DM patients with
gastrointestinal disorders.
– Fasting blood sample is also required
Intravenous Glucose Tolerance Test
(IVGTT)
criteria for FPG:
Non diabetic
Impaire PG
DM
100
100-125
>126
Categories of OGTT:
Normal/Non-diabetic
Impaired GTT
DM
2-hr PG < 140mg/dl
2-hr PG 140-199
mg/dl
2-hr PG
>200mg/dl
Formation of a hemoglobin compound which is produced
when glucose reacts with the amino group of hemoglobin
Glycosylated hb
Increased Glycosylated Hb
Pregnancy in 2nd and 3rd trimester and DM
Decreased gkycosylated hb
Hemoglobinopathies, blood loss, transfusion, Hemolysis
Also known as GLYCATED ALBUMIN
Fructosamine
Inborn errors of CHO metabolism
Galactosemia
Lactose intolerance
Glycogen storage disease
Group of inherited disorders impairing the ability
of the body to process and produce energy from
galactose
galactosemia
characterized by
complete deficiency of Signs and symptoms
include liver dysfunction, susceptibility to
infections, failure to thrive and cataracts
classic galactosemia
Impairs ability of liver to produce free glucose
from glycogen in glycogenolysis and also
affects gluconeogenesis
Glycogen storage disease
Most common GSD; results from deficiency of
glucose 6 phosphatase
GSD Type 1 or Von Gierke disease
Gastrointestinal condition characterized by
low levels of lactase in the small intestine
Lactose intolerance
refers to diabetes occurring as a result of the diseases of exocrine pancreas
Type 3C DM
other names of type 3c dm
– Pancreatogenic or
– pancreatogenous diabetes mellitus.
– Pancreatic diabetes.
– Pancreoprivic diabetes.
causes of type 3c diabetes
• Chronic pancreatitis.
• Acute pancreatitis.
• Pancreatic cancer.
• Hemochromatosis.
• Cystic fibrosis.
• Pancreatectomy
give the minor criteria for type 3c
– Impaired β-cell function
– No excessive insulin resistance
– Impaired incretin or pancreatic polypeptide secretion.
– Low serum levels of lipid (fat) soluble vitamins (A, D, E, or K).
most commonly detected; glucose attached to one
or both N terminal valine of the beta polypeptide chain of
normal adult Hb
HbA1c
Specimen requirement of Glycosylated Hb
EDTA whole blood
Fructosamine is useful for monitoring diabetes with:
Chronic Hemolytic anemia
Hemoglobin variants
Most common and most severe type of galactosemia
Galactosemia type 1
Causes of lactose intolerance
gastrointestinal discomfort
cramps
diarrhea
