Considerations Flashcards
Basal state
Resting metabolic state of the body early in the morning after fasting approximately 12 hours
The effects of diet, exercise, and other controllable factors are minimized or eliminated
How does age affect testing
Rbc and wbc are higher in newborns than in adults
Kidney function (creatinine clearance) decreases with age
How does altitude effect testing
Higher altitude = increase in rbcs, hemoglobin, hematocrit, c reactive proteins and uric acid
Lower altitude = decrease in urinary creatinine and plasma renin
How does dehydration affect testing
Hemoconcentration is which blood components cannot easily leave the blood stream become concentrated in the smaller plasma volume
Affect rbcs, enzymes, iron, calcium, sodium and coagulation factors
How does diet affect testing
Blood specimens collected soon after a meal or snack are unsuitable for many testing
8-12 hour fasting negates this discrepancy
Ammonia, urea, and uric acid increase with beverages containing caffeine
Cortisol and atch levels increase with beverages containing caffeine
Glucose levels increases dramatically with ingestion of carbs or sugary substances but return to normal within 2 hours
Hgb levels decrease and electrolyte balance can be altered by drinking excessive amounts of water and other fluids
Lipid levels increase with ingestion of foods (high fat foods)
Triglycerides, certain liver enzymes and other liver function analytes are increased large amounts of alcohol
How time of day can affect testing…(diurnal variations)
Melatonin is affected by light, increase with dark, decrease with light
Max renin and tsh levels occur in the predawn hours
Peak cortisol levels occur later in the morning
And more
How drug therapy can affect testing
Chemo drugs decrease blood cells, especially wbc and platelets
Many drugs that are toxic to the liver can increase ast, alp and ldh and decrease production of clotting factors
Opiates increase liver and pancreatic enzymes
Oral contraceptives can affect a lot of testing including increasing esr rates and decreasing levels of vit b12
Steroids and diuretics can cause pancreatitis and increase amylase and lipase values
Thiazide diuretics can increase calcium and glucose and decrease sodium and potassium levels
Drugs that interfere with testing should not be taken….
4-24 hours prior to the blood sample
48-72 hours prior to urine sample
How exercise can affect testing
Usually return to normal when stopping exercise
Arterial pH and PaCO2 levels are reduced by exercise
Glucose, creatinine, insulin, lactic acid and total protein are elevated
Potassium increases
Creatinine kinase and ldh remain elevated 24 hours after exercise
Vigorous exercise can temporarily increase cholesterol levels by 6 percent or more, and can affect hemostasis
How fever can affect testing
Increases insulin levels therefore increase glucagon levels
Increases cortisol and may disrupt its normal diurnal variation
How gender can affect testing
Most differences are only apparent after sexual maturity
Rbc, hgb, Hct are higher in males
How jaundice can affect testing
Can affect Chem tests based on color reactions including reagent-strip analysis on urine
Can turn serum, plasma, and urine specimens an abnormal deep yellow or yellow-brown color due to high bilirubin levels
How body position can affect testing
A change in lying to standing can cause up to a 15 percent variation in hdl
Plasma aldosterone and plasma renin activity levels - patient has to be lying down for 30 min prior to collection
Rbc count and potassium are higher in someone who has been standing for 15-30 minutes
How pregnancy can affect testing
Increases body fluid which has a dilution effect on rbcs leading to lower rbc counts
How smoking can affect testing
Smoking before testing can increase cholesterol, cortisol, glucose, growth hormone, triglycerides levels, and wbc counts
Chronic smoking decreases pulmonary function and increases rbcs and hemoglobin levels, decreases immune response (decreases immunoglobulin IgA, IgG and IgM but increases levels of IgE)
