CLS Diagnostic Methods & Technologies 5

Question 1

In flow cytometry, side scatter (SSC) mainly reflects which cellular property?

Accepted Answer

Internal complexity or granularity

Answer

Side scatter is light deflected at about 90° by internal structures, so granulocytes show high SSC.

Question 2

In an impedance (Coulter principle) cell counter, the height of each voltage pulse is proportional to which property?

Accepted Answer

Cell volume

Answer

A cell passing through the aperture displaces conductive fluid, and the size of the resistance change matches the cell's volume.

Question 3

Which CD marker is enumerated by flow cytometry to assess hematopoietic progenitor cell yield before stem cell transplant?

Accepted Answer

CD34

Answer

CD34 is the standard marker for hematopoietic stem and progenitor cells, usually counted with the ISHAGE gating protocol.

Question 4

Which technology lets newborn screening labs measure amino acids and acylcarnitines together from a single dried blood spot?

Accepted Answer

Tandem mass spectrometry (MS/MS)

Answer

MS/MS can quantify dozens of metabolites in one run, which allows panels for amino acid, fatty acid oxidation, and organic acid disorders.

Question 5

A peritoneal dialysis patient using icodextrin has a falsely elevated point-of-care glucose. Which strip chemistry is most likely responsible?

Accepted Answer

Glucose dehydrogenase with PQQ cofactor

Answer

GDH-PQQ is not specific for glucose and also reacts with maltose, which forms when icodextrin is metabolized, so results read falsely high.

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