MLPAO Urinalysis and Body Fluids Case Studies

Question 1

A urine dipstick shows 3+ blood but microscopic examination reveals no red blood cells. What is the most likely explanation?

Accepted Answer

Hemoglobinuria or myoglobinuria — free hemoglobin or myoglobin in urine causes a positive dipstick without intact RBCs

Answer

False positive dipstick

Answer

The microscopy was performed incorrectly

Answer

The dipstick is expired

Question 2

A CSF specimen shows 500 WBC/µL with 95% neutrophils, protein 2.5 g/L, and glucose 1.0 mmol/L (serum glucose 6.0 mmol/L). What is the most likely diagnosis?

Accepted Answer

Bacterial meningitis

Answer

Viral meningitis

Answer

Normal CSF

Answer

Fungal meningitis

Question 3

A patient's urine shows many waxy casts, broad casts, and RTE cells. What does this suggest?

Accepted Answer

Severe chronic renal disease with tubular damage and stasis

Answer

Normal urinalysis

Answer

Acute urinary tract infection

Answer

Dehydration only

Question 4

A pleural fluid analysis shows protein 45 g/L, LDH 500 U/L (serum LDH 200 U/L), glucose 2.0 mmol/L, and many lymphocytes. What diagnosis should be considered?

Accepted Answer

Tuberculous pleuritis or malignancy

Answer

Congestive heart failure

Answer

Pulmonary embolism

Answer

Uncomplicated pneumonia

Question 5

A urine specimen is cloudy with an alkaline pH, positive nitrite, positive leukocyte esterase, and microscopy shows many WBCs, bacteria, and triple phosphate crystals. What is the diagnosis?

Accepted Answer

Urinary tract infection likely caused by a urease-producing organism

Answer

Normal concentrated urine

Answer

Nephrotic syndrome

Answer

Glomerulonephritis

Question 6

A synovial fluid specimen from an acutely swollen knee joint is examined under compensated polarized light. Needle-shaped crystals showing strong negative birefringence (yellow when parallel to the slow ray compensator) are seen. What is the diagnosis?

Accepted Answer

Gout (monosodium urate crystals)

Answer

Pseudogout (CPPD)

Answer

Septic arthritis

Answer

Osteoarthritis