Test 14

Question 1

Sensitivity, specificity, NPV, PPV

Answer 1

A screening test must have a high sensitivity. The high sensitivity helps to ‘RULE OUT’ the dx by decreasing the number of false-negative results, and by increasing the negative predictive value (SnNOut).

Question 2

SLE

Answer 2

Although virtually all patients with SLE screen positive for antinuclear antibody (ANA), the test is nonspecific and can also be positive in healthy populations and in patients with connective tissue dxs. Both the anti-dsDNA and anti-Smith antibodies are associated with SLE, although anti-dsDNA Abs are more sensitive at 66-95%.

Question 3

SLE

Answer 3

Anti-dsDNA Abs and complement levels (immune complex deposition induces complement fixation and leads to low levels of complement) can be used to follow dx activity in SLE patients and is associated with the development of lupus nephritis.

Question 4

Infectious mononucleosis

Answer 4

Infectious mononucleosis is a viral syndrome most commonly caused by Epstein-Barr virus and commonly presents with fever, fatigue, LAD, exudative pharyngitis, and hepatosplenomegaly. Splenic rupture is a rare but dangerous sequela. Spelnomegaly is often present when not detected on PE; therefore, the most important recommendation is for all patients to avoid contact sports to prevent this sequela.