ASCP Chem
Toxic levels of lithium can cause lethargy, apathy, muscle weakness up to and including seizures and coma. What is the toxic level of lithium? -0.5-1.2 mmol/L -1.2-1.5 mmol/L -1.5-2 mmol/L ->2 mmol/L
Lithium has a very low therapeutic level due to its highly toxic effects. However, concentrations starting at 1.5 mmol/L and above can affect the CNS system in serious ways.
To assess drug concentrations during the trough phase: -Blood should be drawn about one hour after the administration of an oral dose of the drug. -Blood should be drawn about half an hour before the next dose is given. -Blood should be drawn about two hours after the administration of an oral dose of the drug. -Blood should be drawnimmediately before the next dose is given.
To assess drug concentrations during the trough phase, blood should be drawn immediately before the next dose is given. If the blood specimen was collected at one or two hours after the administration of an oral dose of the medication, the result would most likely reflect the peak level. If the blood specimen was collected half an hour before the dose is given, it will not be representing the real trough phase.
You are collecting a blood specimen to be used for forensic (legal) alcohol testing. Which of the following must be done before you can start the specimen collection process? -Label the tubes in the presence of the patient. -Must inform the patient that the blood about to be collected is for alcohol testing. -Seal the collection tubes in front of the patient. -Collect the specimen, the patient does not need to be informed what the blood is collected for.
Before starting the blood collection process, the patient must be informed that the specimen collected will be tested for blood alcohol. Labeling the blood tubes and sealing them in front of the patient is done after collection is complete.
All of the following specimen processing examples are considered processing errors that can have a negative impact on the test results, EXCEPT? -Transporting an ammonia specimen to the laboratory in an ice slurry. -Centrifuging a plasma specimen 4 hours after collection. -Rimming the clot in a serum collection tube prior to centrifugation. -A blood specimen that is frozen and thawed a few times before testing.
Blood ammonia levels increase fast at room temperature because of in vitro amino acid breakdown. Therefore, a whole blood ammonia specimen must be placed in an ice slurry, quickly transported to the lab, separated from the cells, and quickly tested. A serum or plasma specimen should be centrifuged within 2 hours of collection. Prolonged plasma/serum contact with the cells increases the possibility of altered analyte levels, intracellular changes, and hemolysis. Rimming the clot in a serum collection tube can cause contamination due to aerosols and hemolyze the specimen. It should be avoided. Freezing and thawing a blood specimen multiple times can hemolyze the red blood cells, affecting the lab results.
Estriol levels in conjunction with hCG, inhibin A (inhA), and alpha-fetoprotein (AFP) can be obtained during pregnancy to assess which of the following? -The risk of Down's syndrome -Fetomaternal function -Multiple gestations -Maternal diabetes mellitus
Estriol "the estrogen of pregnancy" is synthesized by the placenta from precursor substances synthesized in the fetal adrenal and modified in the fetal liver. Measuring maternal serum estriol in conjunction with AFP, inhA, and hCG during the second trimester of pregnancy can be used to help predict the risk (up to 80% of the time) of Down's syndrome. Estriol, AFP, inhA, and hCG run as a panel is referred to as the Quadruple Test or Quad test. - The risk of Down's syndrome
In which of the following condition(s) would an increased serum osmolality be an expected finding? -Increased arginine vasopressin hormone (AVP formerly ADH) secretion -Diabetes insipidus -Hyponatremia -Acute myocardial infarction
In diabetes insipidus, renal insensitivity to vasopressin results in the excretion of an increased volume of dilute urine, a decrease in body water, and a rise in serum osmolality. In hyponatremia and when ADH is abnormally secreted, the serum osmolality values can be expected to decrease.Acute myocardial infarction is not associated with a rise in serum osmolality.
Which of the following is most likely to interfere with the measurement of hemoglobin? -Leukocytopenia -EDTA -Heparin -Lipemia
Increased turbidity of the specimen may interfere with the measurement of hemoglobin and result in a falsely increased hemoglobin result. Lipemia, leukocytosis, paraproteinemia, cryoglobulinemia, cryofibrinogenemia, and presence of abnormal hemoglobin (e.g., HbS, HbC), are all possible causes of increased turbidity.
The parathyroid hormone (PTH) is important in the regulation of: -Iodine and bromine -Calcium and phosphate -Acid and alkaline phosphatase -Zinc and magnesium
PTH is secreted by the parathyroid glands and its major functions are to regulate serum calcium and phosphate. PTH regulates calcium and phosphate by: Stimulating bone resorption or bone formation to increase or decrease serum calcium levels. Increasing reabsorption of renal tubular calcium and decreasing the reabsorption of phosphate by the proximal tubule Enhancing 1a-hydroxylation of 25-hydroxy vitamin D to produce 1,25 (OH)2D which stimulates both calcium and phosphate
Which one of the following is the correct definition of isoelectric point (pI)? -Buffer formation of a positively charged ionic cloud that can affect the migration of the negative ionic cloud of the sample -The ability of a molecule to have both negatively and positively charged groups -The pH where a molecule has a net charge of zero -The movement of charged particles in an electrical field
A molecule that has both negatively charged groups and positively charged groups is described as amphoteric. These charges can be changed by changing the pH of the solution. The pH where there is an equal number of positive and negative charges is the isoelectric point, that is the molecule has a net charge of zero.
Which of the following are considered two of the positive risk factors for coronary heart disease as determined by the National Cholesterol Education Program (NCEP)? -LDL-C concentration < 100 mg/dL; HDL-C concentration = 60 mg/dL -LDL-C concentration = 100 mg/dL; HDL-C concentration = 60 mg/dL -LDL-C concentration < 100 mg/dL; HDL-C concentration < 40 mg/dL -LDL-C concentration = 100 mg/dL; HDL-C concentration < 40 mg/dL
According to the NCEP, there are several positive risk factors for coronary heart disease. Two positive risk factors for coronary heart disease are the LDL-C concentration of = 100 mg/dL and the HDL-C concentration of < 40 mg/dL. According to the NCEP two negative risk factors for coronary heart disease are the LDL-C concentration of <100 mg/dL and the HDL-C concentration of = 60 mg/dL.
Which of the following enzymes is associated with conditions affecting skeletal muscles? -Aldolase -Alkaline phosphatase (ALP) -Gamma-glutamyltransferase -5'-nucleotidase
Aldolase is an enzyme that aids in the glycolytic breakdown of glucose to lactate for energy. Aldolase is associated with muscles and is currently used in the monitoring of patients with muscular dystrophy and a few other rare conditions affecting skeletal muscles. A serum ALP measurement's most useful clinical attribute is its sensitivity in distinguishing hepatobiliary disease associates with biliary tree obstruction. It is also used to detect bone disease associated with an elevated osteoblastic activity. Gamma-glutamyltransferase, or GGT, is elevated in liver diseases affecting the biliary system, especially in patients who are heavy drinkers. Serum concentrations of 5'-nucleotidase, or 5NT, reflect hepatobiliary disease with high specificity as well.
Which of the following blood tests needs to be placed on ice immediately after collection? -Amylase -Sodium -Ammonia -Glucose
Ammonia must be collected in a green-top tube (lithium heparin or sodium heparin) and placed immediately in an ice slurry. Ammonia levels help evaluate liver function.
Approximately how many doses are required to obtain a steady-state oscillation allowing for peak and trough levels to be evaluated? -1 to 2 -3 to 4 -5 to 7 -> 10
Approximately five to seven doses are required before a steady-state oscillation is achieved. After the first dose, absorption and distribution occur, followed only by elimination. Before the concentration of the drug drops significantly, the second dose is given and the peak of the second dose is additive to what remains of the first dose. The third through the seventh scheduled doses all have the same effect, increasing the serum concentration and the amount eliminated. By the end of the seventh dose, the amount of the drug administered is equal to the amount eliminated during the dosage period. At this point, a steady-state is established and peak and trough concentrations can be evaluated.
Why are small dense LDL molecules more atherogenic? -Small dense LDL molecules contain less cholesterol and phospholipid. -Small dense LDL molecules increase the concentration of HDL-C in the blood. -Small dense LDL molecules increase the concentration of adiponectin and inflammatory cytokines. -Small dense LDL molecules have greater mobility in the endothelium and arterial wall.
Most researchers believe that the small size and increased density of LDL molecules found in atherogenic dyslipidemia enable the molecules to more easily invade the endothelium and arterial wall of vessels, making them more proatherogenic. LDL particles are considered to be a good marker for coronary heart disease (CHD) risk.
What is the term used to describe inadequate blood supply that decreases availability of oxygen to the myocardium? -Acute myocardial infarction (AMI) -Angina -Congestive heart failure (CHF) -Myocardial ischemia
Myocardial ischemia - an inadequate blood supply that decreases the availability of oxygen. CHF - a clinical syndrome caused by heart disease, represented by abnormal sodium and water retention and breathlessness, usually resulting in edema. AMI - cardiac tissue death (necrosis) due to lack of oxygen caused by obstruction of circulation. Angina - chest pain caused by an inadequate supply of oxygen to heart myocardium.
Select the equation which is used to determine the pH of a solution containing a weak acid and its salt. -Van Deemter equation -Van Slyke equation -Nernst equation -Henderson-Hasselbalch equation
The Henderson-Hasselbalch equation is as follows: pH = pKa + log ([A-]/[HA]), which is used to calculate the pH of a solution. The Van Deemter equation is used to relate the variance per unit length of a separation column to the linear mobile phase velocity. The Van Slyke equation is for the CO2 equilibration curve of blood in vitro. The Nernst equation is used to calculate the voltage of an electrochemical cell or to find the concentration of one of the components of the cell.
An adult's plasma cortisol of 22 µg/dL at 8:00 a.m. and 10 µg/dL at 4:00 p.m. would be: -Consistent with Addison's disease -Consistent with Cushing's syndrome -Found in a healthy individual -Consistent with pheochromocytoma
The amount of cortisol present in the blood undergoes diurnal variation, with the highest levels present in the early morning, and the lowest levels present around midnight or 3-5 hours after the onset of sleep. Reference intervals for an adult are as follows: 5-23 µg/dL at 8:00 a.m. 3-16 µg/dL at 4:00 p.m. <50% of 8:00 a.m. values at 8:00 p.m. Addison's disease will show lower levels of cortisol and other steroid hormones without fluctuation in the day/night. Cushing's syndrome is associated with high levels of cortisol throughout the day and night. Pheochromocytoma is associated with an increased release of epinephrine and norepinephrine.
After experiencing extreme fatigue and polyuria, a patient's basic metabolic panel is analyzed in the laboratory. The result of the glucose is too high for the instrument to read. The laboratorian performs a dilution using 0.25 mL of patient sample to 750 µL of diluent. The result now reads 325 mg/dL. How should the technologist report this patient's glucose result? -325 mg/dL -1,300 mg/dL -975 mg/dL -1,625 mg/dL
The correct answer for this question is 1,300 mg/dL. The laboratorian performed a 1:4 dilution by adding 0.25 mL (or 250 µL) of patient sample to 750 µL of diluent. This creates a total volume of 1,000 µL. So, the patient sample is 250 µL of the 1,000 µL mixed sample, or a ratio of 1:4. Therefore, the result given by the chemistry analyzer must be multiplied by a dilution factor of 4. 325 mg/dL x 4 = 1,300 mg/dL.
How is the majority of urobilinogen that is produced daily removed from the body? -Through urine excretion -Through sweat -Through saliva -Through fecal excretion
The majority (about 80%) of urobilinogen that is produced daily is broken down further to urobilin in the intestines and excreted in the feces; this is what gives stool its color. The remaining 20% is reabsorbed and recirculated, with some elimination by the kidneys.
Which assay, using 24-hour urine, is considered the BEST single screening test for pheochromocytoma? -Catecholamines -Vanillylmandelic acid (VMA) -Homovallic acid (HVA) -Metanephrines
The most reliable screening test for the diagnosis of pheochromocytoma is the measurement of plasma-free fractionated metanephrines and urinary fractionated metanephrines. Pheochromocytoma is an adrenal or extraadrenal neoplasm that secretes catecholamines. Patients with pheochromocytoma often exhibit persistent and paroxysmal hypertension. Urinary free catecholamines and vanillylmandelic acid are also elevated.
The normal De Ritis ratio (AST/ALT) should be: -Equal or < 1 -2:1 -3:1 -4:1
The normal De Ritis ratio of AST/ALT should be <1 since ALT tends to be higher than AST. In patients with alcoholic hepatitis, the AST will increase higher than the ALT, resulting in a ratio greater than 2. The De Ritis ratio is also used for other liver diseases and indicates the damage to hepatocytes.
Which one of the following is a TRUE statement concerning alkaline phosphatase? -It is optimally active at pH 5 -It is decreased in bone disorders involving the osteoblasts -It is increased in obstructive jaundice -It is increased in myocardial infarctions
The only correct answer is choice 3, as increased levels of alkaline phosphatase are found in patients suffering from obstructive jaundice. This enzyme is optimally active around a pH of 9.0-10.0 and is increased in bone disorders involving osteoblasts such as Paget's disease.
The MOST accurate observation about osmotic pressure is that it is: -Proportional to concentration of solute particles -Equal to number of solvent molecules times a factor -Measurable by how much it raises the freezing point of water -Directly proportional to the inverse log of solvent molecules
The osmotic pressure does not depend on the solute type or its molecular size but only on its molar concentration, the concentration of solute particles. There is no factor involved nor inverse log involved in the osmotic pressure in relation to the solvent molecules in the sample. Osmolality is measurable by how much it depresses the freezing point of samples.
Which of the following lipid results would be expected to be MOST falsely elevated on a serum specimen from a non-fasting patient? -Cholesterol -Triglyceride -HDL -LDL
Triglycerides show marked elevation after an individual eats. So a non-fasting specimen will show a falsely high triglyceride level. Cholesterol does not show much fluctuation after eating. HDL and LDL may be slightly elevated due to a non-fasting sample, but not to the same extent as the triglycerides. This is the reason that patients are told to fast; the laboratory needs a fasting sample to determine a lipid profile or panel which includes the latter four components.
