STP Clinical Sciences 4

Question 1

A 25-year-old woman has a positive lupus anticoagulant, elevated anti-cardiolipin IgG, and a history of recurrent miscarriages. Her APTT does not correct on 1:1 mixing. Which diagnosis is most consistent?

Accepted Answer

Antiphospholipid syndrome

Answer

Antiphospholipid syndrome is characterized by antiphospholipid antibodies (lupus anticoagulant, anti-cardiolipin) causing thrombosis and pregnancy morbidity, with non-correcting APTT confirming an inhibitor.

Question 2

In the context of clinical pharmacology, which pharmacokinetic parameter describes the volume of fluid required to contain all of the drug in the body at the observed plasma concentration?

Accepted Answer

Volume of distribution

Answer

Volume of distribution (Vd) is a theoretical volume that relates total drug in the body to plasma concentration; a high Vd indicates extensive tissue distribution.

Question 3

A patient has sodium 128 mmol/L, urine osmolality 520 mOsm/kg, urine sodium 55 mmol/L, and normal thyroid/adrenal function. Which condition best explains these findings?

Accepted Answer

SIADH

Answer

SIADH presents with euvolemic hyponatremia, inappropriately elevated urine osmolality (>100 mOsm/kg), and elevated urine sodium (>20 mmol/L) with normal thyroid and adrenal function.

Question 4

Which PCR technique allows simultaneous quantification of multiple target sequences in a single reaction by using different fluorescent probes?

Accepted Answer

Multiplex real-time PCR

Answer

Multiplex real-time PCR uses multiple primer pairs and fluorescent probes with distinct emission wavelengths to simultaneously detect and quantify several targets in one reaction.

Question 5

In immunohistochemistry, heat-induced epitope retrieval (HIER) is used primarily to overcome which problem?

Accepted Answer

Antigen masking by formalin cross-links

Answer

Formalin fixation creates protein cross-links that mask antigenic epitopes; HIER uses heat and buffer to break these cross-links and restore antigen-antibody binding capacity.

(STP) Scientist Training Programme Practice Test

(STP) Scientist Training Programme Practice Test

STP Clinical Sciences 4