STP Clinical Sciences 5

Question 1

A 60-year-old male has serum protein electrophoresis showing a monoclonal band in the gamma region. Serum free light chain ratio is 8.2 (normal 0.26-1.65). What additional investigation is most critical to differentiate MGUS from multiple myeloma?

Accepted Answer

Bone marrow trephine biopsy

Answer

Bone marrow trephine biopsy is essential to quantify plasma cell percentage; multiple myeloma requires ≥10% clonal plasma cells plus myeloma-defining events, differentiating it from MGUS.

Question 2

In platelet function testing, a patient shows normal platelet aggregation with collagen but absent aggregation with ADP and absent second wave with epinephrine. Which disorder does this pattern suggest?

Accepted Answer

ADP receptor (P2Y12) defect

Answer

Absent ADP-induced aggregation and absence of the epinephrine second wave (which requires ADP amplification) with normal collagen aggregation is the hallmark pattern of P2Y12 receptor deficiency.

Question 3

A reference interval study is performed on 200 healthy adults. Using a non-parametric method, what percentile range defines the standard reference interval?

Accepted Answer

2.5th to 97.5th percentile

Answer

The standard clinical reference interval encompasses the central 95% of the reference population, defined by the 2.5th to 97.5th percentiles using non-parametric or parametric methods per CLSI EP28-A3c.

Question 4

Which cytogenetic abnormality is the most common translocation found in acute promyelocytic leukemia (APL) and determines eligibility for ATRA therapy?

Accepted Answer

t(15;17)(q24;q21)

Answer

The t(15;17) translocation creates the PML-RARA fusion gene in APL; this fusion protein drives the disease and is specifically targeted by all-trans retinoic acid (ATRA), which induces differentiation.

Question 5

A urine culture grows 10^5 CFU/mL of E. coli. The patient is asymptomatic. Which action is most appropriate according to UK clinical guidelines?

Accepted Answer

Treat only if the patient is pregnant or pre-operative

Answer

Asymptomatic bacteriuria should not be treated in most populations; UK guidelines recommend treatment only in pregnant women and patients undergoing urological procedures to prevent complications.

(STP) Scientist Training Programme Practice Test

(STP) Scientist Training Programme Practice Test

STP Clinical Sciences 5