1. Presented by Abi Norwood, M.D.  and reviewed by Herleen Rai, MD

A child arrives at the emergency department (ED) presenting with fever, fatigue, and dark brown discolored urine. The child has no significant past medical problems.

A history and physical reveals the child had a recent upper respiratory infection. On exam, the child is currently febrile (with a Tmax 102.1°F), lethargic, and exhibiting diffuse jaundice. Initial laboratory results indicate severe anemia (hemoglobin 5.7 g/dL) and signs of hemolysis (total bilirubin: 2.5 mg/dL, lactate dehydrogenase: 2,255 U/L, haptoglobin: <3 mg/dL). An expedited blood bank workup is performed and includes a Donath-Landsteiner test, the results of which are shown below.

Donath-Landsteiner test:

30 minutes 0°C, 60 minutes 37°C​			90 minutes 0°C​			90 minutes 37°C​			​
A1​	A2​	A3​	B1​	B2​	B3​	C1​	C2​	C3​	Interpretation ​
++++​	+++​	0​	++​	+​	0​	++​	+​	0​	Positive

Question:  Given the clinical presentation, what is most likely direct antiglobulin test (DAT) results for this patient?

	Poly Specific (anti-IgG, anti-C3)	Anti-IgG	Anti-C3
A.	+	+	+
B.	+	+	-
C.	+	-	+
D.	-	-	-