CMT Urinalysis and Body Fluids Flashcards

In a cerebrospinal fluid (CSF) analysis, a markedly elevated protein with normal glucose most likely indicates:

Answer: Guillain-Barré syndrome

Guillain-Barré syndrome classically presents with albuminocytologic dissociation: very high CSF protein with a normal cell count and normal glucose.

Which finding in CSF is most consistent with bacterial meningitis?

Answer: Increased protein, decreased glucose, neutrophilia

Bacterial meningitis typically causes elevated CSF protein, reduced glucose (bacteria consume it), and a predominance of neutrophils.

Xanthochromia of CSF refers to:

Answer: Yellow or orange discoloration

Xanthochromia is the yellow or orange pigmentation of CSF due to hemoglobin breakdown products (oxyhemoglobin, bilirubin) after subarachnoid hemorrhage.

When differentiating a traumatic tap from true subarachnoid hemorrhage, which finding supports subarachnoid hemorrhage?

Answer: Uniform RBC count across all tubes

In subarachnoid hemorrhage, blood is uniformly distributed throughout all CSF collection tubes, while a traumatic tap shows decreasing RBCs in successive tubes.

The reference method for synovial fluid crystal identification is:

Answer: Compensated polarized light microscopy

Compensated polarized light microscopy distinguishes monosodium urate (gout, negatively birefringent) from calcium pyrophosphate (pseudogout, positively birefringent) crystals.

A pleural fluid Light's criteria exudate requires LDH greater than what fraction of the upper limit of serum LDH?

Answer: 0.45

By Light's criteria, a pleural fluid is an exudate if pleural fluid LDH is more than 0.45 times (>2/3 of some sources use 0.67, but the classic ratio threshold is >0.6 for the fluid/serum LDH ratio — the threshold here is 0.45 for the pleural LDH/serum LDH upper-limit ratio), indicating an inflammatory process.