Clinical Chemistry
What is the main goal of therapeutic drug monitoring (TDM)?
To keep the level of drug between the lowest concentration known to be toxic, but above the lowest concentration considered effective.
What characteristic finding would you see on the blood smear in Hairy Cell Leukemia?
Lymphocytes with "hair-like" projections on them
A male patient with acute urethritis and purulent discharge came into the hospital. A specimen was collected and intracellular gram negative diplococci in PMNs were found on the gram stain. What is the organism's presumptive identification?
Neisseria gonorrhoeae
Why must pathogen reduction be done on platelet units?
They are kept at room temperature so infectious agents can grow in the unit if not treated.
A positive DAT is indicative of the presence of what?
Bound antibodies already on the RBCs
IgG or C3d antibodies
What are the specimen/transport requirements for lactate samples?
Collect without tourniquet
Collect on ice (prevent lactate from rising)
A patient who is known to have many NRBCs has a CBC ran on an automated analyzer. Would this have an effect on the results and if so what?
Yes, there was be an erroneously high WBC count. The nuclear contents allow them to be counted as WBCs.
An organism that is halophilic indicates what? Name at least one example.
Halophilic - salt requiring
Examples: Vibrio cholerae, Vibrio mimicus, etc.
When doing an antibody identification, the technician adds dithiothreitol or 2-mercaptoethanol to the sample. What is the goal of this step? How does it aid in identification?
DTT/2ME destroy IgM antibodies in the sample.
This allows other IgG antibodies that were also reacting but being covered up to be identified.
Name the anticoagulant and tube color used for coagulation testing. Bonus 100 points if you know why that’s the color used.
Sodium citrate (light blue)
Kenneth Brinkhous (the creator of the APTT test) is from UNC so the color is UNC blue!
Name the five peaks seen in a normal electrophoretic pattern.
Albumin, alpha-1, alpha-2, beta, and gamma
What is the difference between AML subtypes M1 and M2?
M1: AML w/o maturation, >90% blasts, prominent nucleoli, may see auer rods.
M2: AML w/ maturation, 30-89% blasts, auer rods.
A lower respiratory sample is sent to the microbiology lab. The technologist makes a gram stain and evaluates it for acceptability, what are they grading?
PMNs and epithelial cells
PMNs > epithelial
A patient's blood has the following results. What is the most likely Rh haplotype?
Anti-D: 4+ Anti-C: 4+ Anti-E: 0
Anti-c: 0 Anti-e: 4+
R1/R1
What are the expected hemoglobin types and percentages for a sickle cell disease patient?
HgbS: 80 - 95%
HgbF: 5 - 20%
HgbA2: minimal
If a patient is said to have primary hyperthyroidism, what would the TSH and T3/T4 values look like?
Increased T3/T4 (hyper-)
Decreased TSH (due to increased T3/T4)
What is the most common cause of iron overload and what is the treatment?
Hereditary Hemochromatosis (genetic defect causing increased absorption of iron in the intestines)
Therapeutic phlebotomy (removing intact RBCs)
Name the two enteric fecal pathogens that MALDI-TOF often has a hard time differentiating.
Escherichia coli and Shigella spp.
Drug induced hemolytic anemia can sometimes be caused by drugs such as cephalosporins and fludarabine. Name the three types of drug induced hemolytic anemias.
Drug-dependent: Antibody reacts with drug-coated cells and antibody reacts with untreated cells in the presence of the drug
Drug-independent: autoantibody induced by the drug
A TSI slant is inoculated for a specimen to aid in its identification. After 18 hours the slant is all yellow, what sugars does this organism utilize?
Glucose
Lactose and/or Sucrose
A blood gas sample was drawn for a patient with the following results. How would you interpret them?
pH:7.36 pCO2: 27 mmHg HCO3: 19 mEq/L
Fully Compensated Metabolic Acidosis
pH is in the normal range indicating compensation. This patient has a low HCO3 indicating a metabolic issue. The pCO2 has decreased to remove the acid in the system.
Describe the mechanism of disease in Thrombotic Thrombocytopenia Purpura (TTP)?
An autoantibody to the vWF cleaving protein (ADAMTS 13) causes the development of ultra large vWF. Because of this platelet micro-thrombi occlude the capillaries and arterioles.
Beta-lactams are common antibiotics used to fight infection. How do these drugs work?
Inhibit cell wall synthesis by binding enzymes involved in peptidoglycan production.
Name the qualitative and quantitative tests for determining a fetal-maternal hemorrhage in postpartum HDFN patients.
Qualitative: rosette test
Quantitative: flow cytometry or Kleihauer-Betke Acid Elution test
Explain the relationship between pH and free (ionized) calcium. What would you expect on a sample with a decreased pH?
The quantity of free (ionized) calcium is affected by the pH of the blood. H+ ions compete with calcium for protein binding sites.
↑ pH = ↓ H+ ions = more Ca2+ binding = less free Ca2+
↓ pH = ↑ H+ ions = less Ca2+ binding = more free Ca2+