It was overuse of paracetamol, which eventually led to Nic Petermann’s cancer diagnosis. For months, the then 26-year-old struggled with exhaustion, night sweats, recurring fever and such annoying stomach pains that she regularly woke up in the middle of the night to take soothing baths. Her ongoing flu-like symptoms, she had read online, were likely just the lingering effects of a Covid infection she had in January 2021; The pain revealed the strange symptom, but an ultrasound had revealed nothing.
In June, the pain was unbearable – Petermann called a telemedicine hotline and was immediately referred to the hospital after staff learned how much acetaminophen she had been taking. After extensive testing, Petermann finally had an answer: All of her symptoms, even those that seemed to be due to Covid for a long time, were due to stage IV Hodgkin lymphoma. The next day she started chemotherapy.
Today, Petermann is in remission, although she is still struggling with the after-effects of months of aggressive chemotherapy. If she hadn’t assumed that most of her symptoms were due to long Covid, she might have received proper treatment and diagnosis much sooner. “When I had my pain symptoms evaluated, I didn’t mention the flu-like symptoms because I felt I had to deal with them,” she says.
Most people with Petermann’s symptoms will not get into their situation. Long Covid is widespread – estimates of its prevalence vary widely, but even the most conservative studies suggest millions of people are struggling with long-lasting symptoms of their infections. Hodgkin lymphoma, on the other hand, is rare. But with dozens of possible symptoms, Long Covid can easily be confused with myriad other conditions, including cardiovascular diseases like high blood pressure and diabetes, autoimmune diseases like lupus and multiple sclerosis, and cancer. Add in the fact that Covid can exacerbate pre-existing conditions and determining whether or not someone has had Covid for a long time becomes a daunting task.
Analyzing this multitude of alternatives is the responsibility of clinicians at the forefront of long Covid care, from the GPs who see patients first to the experts overseeing long Covid clinics. For each patient, they must conduct a careful differential diagnosis, a medical term for the process of considering all possible causes of a patient’s symptoms.
Accurate differential diagnosis is essential not only for patient care, but also for medical understanding of an as yet unclear condition. “We have to be careful not to make long-term Covid a collective diagnosis,” says Linda Geng, co-director of the Stanford Post-Acute Covid-19 Syndrome Clinic.
In the absence of objective testing, however, Covid has long remained a “diagnosis of exclusion” – a diagnosis made only after other reasonable options have been exhausted. Recent data suggests that many patients will emerge from this process not with a diagnosis of Long Covid but with something else. A July newspaper Nature which analyzed the medical records of over 2 million patients in the UK found that 5.4 per cent of patients with a previous Covid infection had recorded at least one long-term Covid symptom in their medical records, 4.5 per cent without Evidence of infection also had at least one symptom.