A urine dipstick is strongly positive for blood, but no red blood cells are seen microscopically. Which explanation is most likely?
1Contamination with menstrual blood
2A false negative dipstick reaction
3Hemoglobinuria or myoglobinuria✓ 정답
4Bacterial overgrowth in the specimen
해설
The reagent strip reacts with the heme moiety, so it is also positive with free hemoglobin or myoglobin, not only with intact red cells. This discrepancy is seen in intravascular hemolysis and in rhabdomyolysis, and further testing is needed to distinguish the two.