Week 4 Lab: Pre-Analytical Variables Flashcards
Components of Pre-analytical Phase?
- Test ordering/requisition
- Patient identification
- Phlebotomy
- Specimen transport
- Specimen examination
- Centrifugation
- Time to testing and storage
Any influence before testing of the specimen that causes the test to fail to reflect the patient’s in vivo body functions
Pre-analytical variables
Factors leading to preanalytical variability?
- Complex biochemical and cellular reactions measured in assays
- Lability of several analytes
- Dependence of reactions on certain substances
Tests most affected by diet?
Glucose and Triglycerides
It can interfere with any test result.
Lipemia
turbidity of the serum or plasma and potentially interfering with instrument readings
Hyperchylomicronemia
Diet elevates?
plasma potassium, alkaline phosphatase, and 5-HIAA (5-Hydroxy indoleacetic acid)
Effects of long-time vegetarian diets?
decreased concentrations of low-density lipoproteins (LDLs), very-low-density lipoproteins (VLDLs), total lipids, phospholipids, cholesterol, and triglycerides.
A high meat or other protein-rich diet affects?
serum urea, ammonia, and urate levels
High protein, low carbohydrate diets cause?
greatly increase ketones in the urine and increase the serum blood urea nitrogen (BUN)
High unsaturated-to-saturated fatty acid causes?
decreased serum cholesterol
Purines cause?
increased urate value
Bananas, pineapples, tomatoes, and avocados cause?
elevated urine excretion of 5-HIAA due to serotonin content
Obesity causes?
Increased serum LD activity, cortisol production, and glucose. Plasma insulin concentration –> increased; glucose tolerance is impaired.
Obese men causes?
reduced testosterone concentration
Alcohol consumption causes?
transient elevation in glucose levels
Chronic alcohol consumption causes?
tests associated with the liver and increases triglycerides
Caffeine causes?
affect hormone levels; elevate plasma free fatty acids and cause catecholamine release from the adrenal medulla and brain tissue
Drinking too much liquid affects?
hemoglobin levels and electrolyte balance
Basal state collection is used for what tests?
glucose, cholesterol, triglyceride and electrolytes
Specimen that requires fasting?
FBS, GTT, TAG, lipid and lipoprotein tests, gastrin and insulin
8-14 hours fasting is used for what tests?
glucose, lipids, and lipoproteins
48 hours of fasting may?
increase serum bilirubin
72 hours of fasting may result to?
increase of plasma triglyceride while glucose decreases in health women to 45 mg/dL (2.5 mmol/L), while men show an increase in plasma triglycerides, glycerol, and free fatty acids, with no significant change in plasma cholesterol
Changes in patient posture from a supine to an erect position affects?
cellular elements, plasma proteins, compounds bound to plasma proteins, and high molecular-weight substances
NIH recommends?
that patients be lying or sitting for 5 minutes prior to blood collection for lipid profiles to minimize the effects caused by posture
Congestive heart failure and liver diseases cause?
increased fluid to remain in the tissue
Changing from supine to sitting or standing causes?
Increased levels of albumin, enzymes, and calcium
Changing from sitting to supine causes?
Increased levels of proteins, lipids, BUN, iron and calcium
Changing from standing to supine causes?
Decreased levels of cholesterol, triglycerides and lipoproteins
30 minutes of standing causes?
Significant elevation of potassium
Prolonged bedrest causes?
Decreased plasma albumin
Standing effects?
Plasma renin is higher than supine position
It is recommended that tourniquet application should not be more than?
one minute
Prolonged tourniquet application results in ________________. The pressure from the tourniquet causes biological analytes to leak from the tissue cells into the blood.
hemoconcentration and anaerobiosis
Prolonged tourniquet application causes increased levels of?
Increased levels: potassium (1 mmol/L), proteins (albumin), enzymes, lactate, cholesterol, and ammonia
Prolonged tourniquet application causes decreased levels of?
Venous pO2 and pH
Moderate or strenuous exercise causes?
increasing the blood levels of creatinine, fatty acids, lactic acid, aspartate aminotransferase (AST), creatine kinase (CK), lactic dehydrogenase (LD), aldolase, hormones (antidiuretic hormone, catecholamines, growth hormone, cortisol, aldosterone, renin, angiotensin), bilirubin, uric acid, high-density lipoprotein (HDL), and white blood cell (WBC) count and decreasing arterial pH and PCO2
Physical activity can have different effects on analyte concentrations, such as?
volume shifts between the vascular and interstitial compartments, volume loss by sweating and changes in hormone concentration
Exercise causes increased?
- Prolactin
- Testosterone
- LH
- Protein (urine)
- Potassium, Lactate, and Phosphate (fist clenching)
Exercise causes a transient increase in?
- Lactate
- Pyruvate
- Fatty Acid
- Creatinine
- Ammonia
Exercise causes a long-term increase in?
- CPK
- AST
- LD
- Aldolase
Exercise causes a decrease in?
- FSH
- LH (In long-distance athletes)
Stress/Anxiety causes?
Increased levels of adrenal hormones (cortisol and catecholamines), increase WBC counts, decrease serum iron, and markedly affect arterial blood gas (ABG) results
WBC counts collected from a violently crying newborn may be markedly?
elevated
Severe anxiety causes?
hyperventilation –> acid-base imbalances and increased lactate and fatty acid levels
Mild stress causes?
- increase in total cholesterol
- HDL cholesterol to decrease by as much as 15%
Immediate effects of nicotine?
- Increase in plasma catecholamines, cortisol (decreased numbers of eosinophils, while neutrophils, monocytes, and plasma fatty-free acids increase), glucose, blood urea nitrogen (BUN), cholesterol, and triglycerides
- Glucose and BUN can increase by 10% and triglycerides by 20%
Chronic smoking increases?
hemoglobin, red blood cell (RBC) counts, the mean corpuscular volume (MCV) and immunoglobulin (Ig) E
Chronic smoking decreases?
Immunoglobulins IgA, IgG, and IgM are decreased, lowering the effectiveness of the immune system
Tobacco smokers have high?
blood carboxyhemoglobin levels
High-altitude areas such as the mountains where there is reduced oxygen levels cause?
RBC counts and hemoglobin (Hgb) and hematocrit (Hct) levels increased. The body produces increased numbers of RBCs to transport oxygen throughout the body.
Laboratory results vary between infancy, childhood, adulthood, and the elderly because?
there is a gradual change in the composition of body fluids
Hormone levels vary with age and gender. RBC, Hgb, and Hct values are higher for?
males than for females
During pregnancy, there is increased plasma volume, which can cause?
a dilutional effect
The dilutional effect causes?
lower RBC counts, protein, alkaline phosphatase, estradiol, free fatty acids, and iron values
It is the normal fluctuation in blood levels at different times of the day based on a 24-hour cycle of eating and sleeping.
Diurnal rhythm
Diurnal variation: which analyte levels are highest in the morning?
Cortisol, aldosterone, renin, luteinizing hormone, follicle-stimulating hormone, estradiol, thyroid-stimulating hormone (TSH), testosterone, bilirubin, hemoglobin, insulin, potassium, RBC count, and serum iron levels
Diurnal variation: which analyte levels are lower in the morning?
Eosinophil counts, creatinine, glucose, triglyceride, and phosphate levels
Medications that are toxic to the liver can cause?
an increase in blood liver enzymes and abnormal coagulation tests
Patients taking medications that impair renal function cause?
Elevated BUN levels or imbalanced electrolytes
Patients taking corticosteroids, estrogens, or diuretics can develop pancreatitis and would have?
elevated serum amylase and lipase levels
