🩺 Q572: In a competitive ELISA for a hormone, what is the relationship between the concentration of the unlabeled patient antigen and the signal intensity?
Anonymous Quiz
0%
A) Directly proportional
100%
B) Inversely proportional
0%
C) No relationship
0%
D) Logarithmic increase
🩺 Q573: Which HLA class of molecules is predominantly responsible for the presentation of exogenous antigens to CD4+ T-helper cells?
Anonymous Quiz
10%
A) HLA-A
70%
B) HLA-B
10%
C) HLA-C
10%
D) HLA-DR
🩺 Q574: Which lab finding is most specific for the diagnosis of Rheumatoid Arthritis?
Anonymous Quiz
9%
A) Elevated Rheumatoid Factor (RF)
91%
B) Anti-cyclic citrullinated peptide (anti-CCP)
0%
C) Elevated ESR
0%
D) Positive ANA
🩺 Q575: A patient has a reactive RPR test but a non-reactive FTA-ABS test. What is the most likely explanation for these results?
Anonymous Quiz
9%
Active primary syphilis
27%
B) Late latent syphilis
64%
C) Biological false-positive RPR
0%
D) Neurosyphilis
🩺 Q576: Which of the following is an example of a Type III hypersensitivity reaction?
Anonymous Quiz
18%
A) Contact dermatitis
18%
B) Serum sickness
55%
C) Goodpasture syndrome
9%
D) Tuberculin skin test
🩺 Q577: A urine specimen shows a positive result for blood on the dipstick but microscopic examination reveals no intact red blood cells. What is the most likely cause?
Anonymous Quiz
9%
A) Hematuria
91%
B) Myoglobinuria
0%
C) Pyuria
0%
D) Glucosuria
🩺 Q578: A patient with nephrotic syndrome provides a urine sample. Microscopic examination reveals oval fat bodies. These structures are most likely degenerated:
Anonymous Quiz
0%
A) Red blood cells
18%
B) White blood cells
73%
C) Renal tubular epithelial cells
9%
D) Squamous epithelial cells
🩺 Q579: Which crystal is described as a 'coffin-lid' appearance and is typically found in alkaline urine?
Anonymous Quiz
0%
A) Calcium oxalate
100%
B) Triple phosphate
0%
C) Uric acid
0%
D) Cystine
🩺 Q580: A urine specimen appears port-wine colored. Upon testing, the sample is negative for blood. Which substance should be suspected?
Anonymous Quiz
9%
A) Bilirubin
73%
B) Porphyrins
18%
C) Myoglobin
0%
D) Melanin
🩺 Q581: Which type of cast is most indicative of chronic renal failure and is characterized by a wide, homogeneous, 'waxy' appearance?
Anonymous Quiz
9%
A) Hyaline cast
55%
B) Granular cast
27%
C) Waxy cast
9%
D) Fatty cast
🩺 Q582: A dipstick test is positive for nitrites. What does this result primarily indicate?
Anonymous Quiz
9%
A) Presence of leukocytes
91%
B) Presence of gram-negative bacteria
0%
C) Presence of protein
0%
D) Presence of glucose
🩺 Q583: Which crystal is pathognomonic for severe liver disease and appears as yellow, concentric spheres with radial striations?
Anonymous Quiz
0%
A) Tyrosine
73%
B) Leucine
18%
Cystine
9%
D) Cholesterol
🩺 Q584: When performing a urine dipstick, what is the significance of a positive bilirubin and a negative urobilinogen?
Anonymous Quiz
9%
A) Hemolytic jaundice
73%
Biliary obstruction
18%
C) Liver cell damage
0%
D) Normal findings
🩺 Q585: A 55-year-old patient with cirrhosis presents with increased ammonia levels. Which of the following is the most critical pre-analytical requirement for accurate venous ammonia measurement?
Anonymous Quiz
20%
A) Use of a red-top tube with immediate centrifugation at room temperature
70%
B) Sample must be placed on ice and plasma separated immediately
0%
C) Patient must be fasting for 24 hours to prevent protein interference
10%
D) Use of serum separator tube to prevent hemolysis
🩺 Q586: A patient with suspected pheochromocytoma has elevated plasma free metanephrines. What is the primary advantage of measuring plasma free metanephrines over 24-hour urinary VMA?
Anonymous Quiz
33%
A) Higher sensitivity due to continuous secretion of catecholamines
56%
B) Lower cost and faster turnaround time in the laboratory
11%
C) Less interference from dietary intake of bananas and caffeine
0%
D) Reduced risk of false positives from chronic hypertension
🩺 Q587: A patient presents with severe fatigue and a CBC showing macrocytic anemia. The peripheral smear reveals hypersegmented neutrophils and ovalocytes. Which lab finding would confirm a diagnosis of folate deficiency over B12 deficiency?
Anonymous Quiz
33%
A) Elevated methylmalonic acid (MMA)
67%
B) Normal methylmalonic acid (MMA)
0%
C) Decreased serum homocysteine
0%
D) Elevated serum gastrin
🩺 Q588: A patient on heparin therapy for DVT develops a sudden drop in platelet count from 250,000/uL to 80,000/uL. Which assay is the gold standard for confirming Heparin-Induced Thrombocytopenia (HIT)?
Anonymous Quiz
20%
A) Platelet aggregation study
30%
B) Heparin-PF4 ELISA
50%
C) Serotonin Release Assay (SRA)
0%
D) Prothrombin Time (PT) mixing study
🩺 Q589: A CSF culture from a patient with meningitis grows a Gram-negative diplococcus that is oxidase-positive and ferments glucose and maltose. What is the most likely pathogen?
Anonymous Quiz
0%
A) Neisseria gonorrhoeae
82%
B) Neisseria meningitidis
9%
C) Moraxella catarrhalis
9%
D) Haemophilus influenzae
🩺 Q590: An isolate from a blood culture is a Gram-positive coccus in clusters, catalase-positive, coagulase-positive, and resistant to oxacillin. What is the mechanism of resistance?
Anonymous Quiz
0%
A) Production of beta-lactamase
91%
B) Altered penicillin-binding protein (PBP2a)
9%
C) Increased cell wall thickness
0%
D) Hydrolysis of the methicillin ring
🩺 Q591: In a patient with suspected Celiac disease, which antibody is considered the most sensitive and specific for diagnosis?
Anonymous Quiz
0%
Anti-gliadin IgA
45%
B) Anti-endomysial antibody
55%
C) Tissue transglutaminase (tTG) IgA
0%
D) Anti-reticulin antibody