CHEMICAL EXAM prt.1.3 Flashcards
GLUCOSE
•Ideal specimen:_____
•For diabetes monitoring:_____
fasting specimen
2-hour post-prandial specimen
•Most frequently performed chemical analysis on urine
GLUCOSE
•Early diagnosis of diabetes mellitus through blood and urine glucose tests provides a greatly improved prognosis
Blood glucose levels fluctuate, and a non-fasting normal person may have_____ following a meal containing a high glucose content
glycosuria
GLUCOSE
CLINICAL SIGNIFICANCE
Hyperglycemia-associated…(2)
Diabetes mellitus
Nondiabetic origin
HYPERGLYCEMIA
Nondiabetic origin CHAPPS
• Cushing syndrome
• Hyperthyroidism
• Acromegaly
• Pancreatitis
• Phylomotoma
• Severe stress
GLUCOSE
CLINICAL SIGNIFICANCE
•Renal-associated
• End-stage renal disease
• Fanconi syndrome
• May be caused by cystinosis
Measurement of glucose by copper reduction method
A color change progressing from a negative blue (CuSO4) through green, yellow, and orange/red (Cu2O)
CLINITEST
CLINITEST
Measurement of glucose by _____ method
A color change progressing from a____ through______
copper reduction
negative blue (CuSO4)
green, yellow, and orange/red (Cu2O)
Intermediate products of fat metabolism
KETONES
KETONES (3)
•Acetone (2%)
•Acetoacetic acid (20%)
•B-hydroxybutyrate (78%)
Present only when the use of available carbohydrates becomes compromised
Fats are metabolized to supply energy in lieu of carbohydrates
Normally no measurable ___ are produced
KETONES
KETONES
• Renal threshold:_____
• Also eliminated in the____
70 mg/dL
lungs
FORMATION of KETONES
•Normal end products of fatty acid metabolism are_____ and ____
Limited availability of
carbohydrates forces the liver to oxidize_____
carbon dioxide and water
fatty acids
KETONES
CLINICAL SIGNIFICANCE
Inability to metabolize carbohydrate
Increased loss of carbohydrate
Inadequate intake of carbohydrate
KETONES
Inability to metabolize carbohydrate
Diabetes mellitus
mostly type 1 (diabetic ketoacidosis)
KETONES
Increased loss of carbohydrate
Vomiting
KETONES
Inadequate intake of carbohydrate
Prolonged starvation
Malabsorption/pancreatic disorders
Severe alcoholism (alcoholic ketoacidosis)
- Patients can have breath that smells fruity or like nail polish remover (acetone breath)
DIABETIC KETOACIDOSIS
Because of the acidosis, patients often breathe very deeply and rapidly to eliminate carbon dioxide and cause respiratory alkalosis (Kussmaul breathing) and can experience respiratory distress due to the prolonged exertion of respiratory muscles.
DIABETIC KETOACIDOSIS
•Patients are usually very dehydrated from being hyperglycemic
high glucose levels lead to osmotic diuresis, involving greater osmole concentrations that cause an
increased osmotic pressure, which leads to reduced water reabsorption in the kidneys.
DIABETIC KETOACIDOSIS
•Once carbohydrate stores become depleted and gluconeogenesis cannot occur anymore, ketogenesis is substantially increased, leading to metabolic acidosis.
DIABETIC KETOACIDOSIS
Because of the acidosis, patients often breathe very deeply and rapidly to eliminate carbon dioxide and cause respiratory alkalosis (_______breathing)
Kussmaul
The pathophysiology starts with low glycogen stores and a lack of oral food intake
shifts the metabolism from carbohydrates to fats and lipids
Decreased oral intake causes decreased insulin levels and increased counter-regulatory hormones such as cortisol, glucagon, and epinephrine
• Ethanol is metabolized to acetaldehyde and acetyl-CoA, leading to an increased NADH/NAD+ ratio
•End result: increased NADH/NAD+ ratio increases lipid metabolism and increased breakdown of lipids to ketoacids
ALCOHOLIC KETOACIDOSIS
CLASSIC TESTS FOR KETONE
Ferric chloride test (Gerhardt’s test,
1865)
Nitroprusside test (Legal’s test, 1883; modified by Rothera in 1908)
Discontinued due to many false-positive reactions (salicylates)
Ferric chloride test (Gerhardt’s test,
1865)
More sensitive to acetone and acetoacetate than reagent strips
•Acetoacetate: 1-5 mg/dL
• Acetone: 10-25 mg/dL
Nitroprusside test (Legal’s test, 1883; modified by Rothera in 1908)
Nitroprusside test
• Acetoacetate:
• Acetone:
1-5 mg/dL
10-25 mg/dL
KETONES
REAGENT STRIP REACTIONS
Uses _______to measure ketones
______reacts with sodium nitroprusside to produce a change in color from____ to ____
•The addition of_____ enables detection of____ (Chemstrip)
sodium nitroprusside (nitroferricyanide)
Acetoacetate
beige to purple
glycine; acetone
KETONES
REACTION INTERFERENCE
•False positive (difference: color fades rapidly on standing)
Phthalein dyes
Highly-pigmented red urine
Levodopa (medication for Parkinson’s disease)
Medications containing free sulfhydryl groups (MESNA, captopril)
KETONES
REACTION INTERFERANCE
•False negative
Improperly preserved specimens due to rapid volatilization of ketones (remedy: test immediately or refrigerate!)
• Confirmatory test for questionable ketone strip results
•May be used on other specimens
ACETEST TABLETS
ACETEST TABLETS
• Contains (3)
1 drop of specimen into the tablet and wait for 30 seconds
nitroprusside
glycine
lactose
KETONES
REAGENT STRIP REACTIONS
Acetoacetate:
Acetone:
5-10 mg/dL
20 mg/dL
