Carbohydrates (Part 3) Flashcards
Hexokinase reagents and products
Reagent: hexokinase and glucose-6-phosphate dehydrogenase
Products: glucose6-phosphate and 6-phosphoglyconate +NADPH + H
A two step reaction that is proposed to be the reference method when a protein-free filtrate is used
Hexokinase
The first step of hexokinase is ________ while the second is ________
specific; non-specific
absorbance in hexokinase is measure at ________
340 nm
A two-step reaction with the first step being specific and the second, non-specific; good method for serum, plasma, urine, and csf; o-dianisidine is the chromogen
Glucose oxidase; “trinder”
Glucose Oxidase “Trinder” reagents
glucose oxidase; peroxidase
Plasma glucose reference interval
-Adults
70-100 mg/dL
Plasma glucose reference interval
-children
70-100 mg/dL
Plasma glucose reference interval
-preemies
25-80 mg/dL
Plasma glucose reference interval
-term babies
60-95 mg/dL
CSF glucose reference interval
60-70% of concommitant plasma levels
Patient preparation instructions for an oral glucose tolerance test (OGTT)
1 minimum of 150 g CHO for 3 days prior to test
2 fasting for 10-16 hrs (water only)
3 discontinue medications that alter glucose levels
4 normal amount of activity before and during test
Three indications for performing an intravenous glucose tolerance test
malabsorption, sprue (Celiac Disease), GI surgery
can be used for preliminary diagnosis of diabetes mellitus; give 75 g oral glucose load or have patient eat a meal; 2 hours later if glucose is _____ may be diabetic
Postprandial Testing; >126 mg/dL
used to diagnose gestational diabetes, performed at _____to_____ weeks gestation; give _____ g glucose load to fasting patient and draw sample at 1 hour; if ____mg/dL perform OGTT
O’Sullivan Test; 24-28 weeks; 50g; >140 mg/dL
ESSAY
metabolic pathway that leads to ketone body formation
formed from Beta-oxidation of free fatty acids
ESSAY
Name three ketone bodies and their specific relative proportions in the blood
1 Beta-hydroxybutyric acid (78%)
2 Acetoacetic acid (20%)
3 Acetone (2%)
ESSAY
Specific starting points of ketone bodies
*pyruvate, amino acids, and fatty acids
Three processes that lead to ketosis due to patients deficiency of glucose
decreased sodium, decreased bicarbonate, and decreased blood pH
Why does patient develop acidosis and hyperlipidemia?
The body is using fatty acids as energy in hyperlipidemia.
Increased in free ketone bodies produce excess H+ ions in acidosis.
Five conditions of decreased CHO availability that can lead to ketosis
starvation, frequent vomiting, glycogen storage diseases, alkalosis, and alcoholism
ESSAY
Specific reagent used in colorimetric method (Acetest or Ketostix)
Sodium nitroprusside
ESSAY
Specific relative reactivity with each of the three ketone bodies in the colorimetric method
Reacts ONLY with acetone and acetoacetate; five times more sensitive to acetoacetate; does NOT react with beta hydroxybutyrate
ESSAY
specimen storage requirements for the colorimetric method (Acetest/Ketostix)
Keep container closed and keep refridgerated
Describe the pathogenies of hyperosmolar hyperglycemic nonketonic coma (HHNC)
- occurs in older patients
- Increased blood glucose (no ketosis)
- Increased osmolality
- Intracellular dehydration
- cellular edema in brain
Three causes of Type A lactic acidosis
Decreased tissue oxygenation from:
- shock
- hypovolemia
- cardiac failure
5 causes of Type B lactic acidosis
Metabolic causes associated with disease (DM, neoplasia, liver diseases) or dug/toxins (alcohol, salicylates)
5 causes of increased CSF lactate
- CVA
- Intracranial hemorrhage
- Bacterial meningitis (normal in viral)
- Epilepsy
- Other CNS disorders
Patient preparation, specimen collection, and sample analysis requirements for lactate
- no tourniquet
- no exercising of arm
- must be placed on ice IMMEDIATELY
- separate from cells within 15 minutes of draw
Essay?
describe the process of glycation
Glycation is the non-enzymatic addition of a sugar residue to amino groups of protein
Essay?
Why can the measurement for glycated hemoglobin be used to assess diabetic blood sugar control over a three to four month at a time span?
Since glycated hemoglobin formation is irreversible AND the normal RBC lifespan is 120 days, these tests assess diabetic compliance with therapy for the preceding 120 days! Levels are unaffected by day-to-day fluctuation, exercise, etc
Essay?
Two general categories of glycated hemoglobin measurement methods
- Methods based on charge differences
2. Methods based on structural differences
Specific clinical application of measuring:
- Insulin
Evaluates fasting hypoglycemia; not necessary to measure to diagnose diabetes mellitus
Specific clinical application of measuring:
- Proinsulin
Evaluates patients with benign or malignant beta-cell tumors of pancreas
Specific clinical application of measuring:
- C-Peptide (3)
Evaluates fasting hypoglycemia, insulin-producing beta-cell tumors, response to pancreatic surgery
Specific clinical application of measuring:
- Urine glucose
Uses glucose oxidase to produce color change; specific for glucose only
Specific importance of urinary albumin and miroalbumin measurements in predicting diabetic nephropathy
persistent proteinuria is the best indicator for renal disease and can be used to screen diabetics for nephropathy development
Importance of urinary micro albumin excretion
It precedes nephropathy and is a marker for mirovascular disease!
