Isolated HBc IgM false reactivity in the absence of acute Hepatitis B: a case report
This case report describes a 28-year-old male with multiple sclerosis whose initial isolated HBc IgM positivity was determined to be a false-positive result caused by heterophile antibodies, as confirmed by undetectable viremia and negative results upon retesting with a heterophilic blocking tube.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Imagine your body is a high-tech fortress, and the medical lab is the security team checking for intruders. Usually, when they find a specific "wanted poster" (a marker) for the Hepatitis B virus, they know exactly who the intruder is. But sometimes, the security system gets confused by a glitchy signal, flashing a red alert for a criminal who isn't actually there.
That's exactly what happened in this story about a 28-year-old guy who walked into the emergency room with a headache and some weird tingling on his left side. Doctors ran a brain scan and found he had a very active case of multiple sclerosis, a condition where the body's immune system gets a bit too excited and attacks the nervous system. He was about to start a powerful new treatment called ocrelizumab to calm things down.
Before starting that treatment, the doctors ran a standard check-up to make sure he didn't have any hidden infections. Everything looked normal: his blood count was fine, his liver enzymes were behaving, and he tested negative for HIV, Hepatitis C, and even the usual Hepatitis B signs. But then, a follow-up test two weeks later threw a curveball.
The lab reported that he had isolated HBc IgM antibodies. In the world of Hepatitis B, finding this specific antibody usually means the person is in the middle of a fresh, acute infection—like catching a cold right now. It's a big deal because if you have an active infection, you can't just start certain treatments without a plan.
But here's where the plot thickens: the patient had no symptoms of Hepatitis B. His liver was happy. He had no fever. And when they looked for the actual virus itself (the HBV DNA) in his blood, it was completely invisible—undetectable. It was like finding a "Wanted" poster for a bank robber in a town where the bank is still open, the vault is untouched, and the police have no record of a robbery.
The doctors suspected a "ghost signal." They knew that sometimes, the body produces heterophile antibodies—these are like mischievous little gremlins that can stick to test kits and trick them into saying "Yes!" when the answer is actually "No." These gremlins often show up in people with autoimmune issues, like the multiple sclerosis this patient had.
To catch the gremlin, the team ran a special test. They took the patient's blood and treated it with a "blocking tube" designed to neutralize these tricky antibodies. When they re-tested the blood after this treatment, the "Wanted" poster for Hepatitis B vanished. The result turned negative. They also sent a sample to a different lab with a different machine, and that lab also said, "Nope, no Hepatitis B here."
So, what did they learn? The paper suggests that the initial positive result was a false alarm caused by those heterophile antibodies messing with the test. It wasn't a new Hepatitis B infection; it was just a case of the test kit getting confused.
The authors point out that while labs have gotten better at stopping these gremlins from messing with the main Hepatitis B marker (HBsAg), this case shows they can still cause trouble with other markers, like HBc IgM. They argue that when a test result doesn't make sense with the patient's story—like a positive infection test in a perfectly healthy liver—doctors and scientists need to pause and double-check. They even suggest that test manufacturers should add a warning about this specific type of confusion in their instruction manuals, because right now, it's a bit of a hidden trap.
In the end, the patient didn't have Hepatitis B. He just had a very confused test kit, and thanks to some detective work, the medical team cleared the name of the virus and could safely move forward with his multiple sclerosis treatment.
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