Red urine without RBCs is seen in:
**Core Concept**
Red urine without RBCs is a clinical presentation that can be caused by various conditions affecting the urinary system. Hemoglobinuria, myoglobinuria, and porphyrins can cause red discoloration of the urine without the presence of red blood cells (RBCs).
**Why the Correct Answer is Right**
The correct answer is caused by the presence of hemoglobin in the urine, which can occur due to intravascular hemolysis. This can be seen in conditions such as sickle cell crisis, hemolytic uremic syndrome (HUS), or severe burns. The hemoglobin breaks down into biliverdin and then bilirubin, which is excreted in the urine, causing it to appear red or tea-colored.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not specify a condition that would cause red urine without RBCs.
* **Option B:** This option is incorrect because myoglobinuria, caused by muscle breakdown, would typically cause a dark brown or tea-colored urine, not red.
* **Option C:** This option is incorrect because porphyrins can cause urine to appear red or dark, but it is typically accompanied by other symptoms such as neurological or abdominal pain.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that red urine without RBCs can be a sign of an underlying condition that requires prompt medical attention, such as hemolytic uremic syndrome (HUS).
**Correct Answer: C. Porphyrins.**