Society looks upon doctors as among the smartest people around. When people get sick, it is expected that their doctor will make them feel better. Doctors study for a very long time. Four years of pre-med, four years of medicine proper, one year of internship, two to four years of residency and one to four years of fellowship. Learning for doctors is a lifelong activity and we have to continuously update our knowledge in order to take the best care of our patients. For those of us who did specialty and subspecialty training in the United States, we are encouraged to recertify every ten years with an exam because of how quickly the practice of medicine changes.
It is therefore understandable that a patient can get frustrated when they see a doctor who cannot quickly diagnose his or her illness. Doctors diagnose diseases by observing patterns. Most of the time, these patterns make sense and point us in the right direction. Unfortunately, some people will have rare diseases that are difficult to recognize, especially for general practitioners who may have never seen these. Sometimes, a common disease with an unusual pattern can be mistaken for something else. Occasionally, the symptom pattern is prolonged and spread out over months to years and the patient is still in the early stages of the disease which has not yet fully evolved to its typical form. Nevertheless, the race is on from the point when the patient starts feeling bad to coming up with a good diagnosis followed by proper treatment.
Diagnosing disease is such a fundamental part of being a doctor that it is one of the first things we learn in medical school. A common misperception is that doctors just simply order laboratory tests in order to make a diagnosis. This is actually one of the last things we do.
Figuring out what’s wrong with a person starts with a history: the chief complaint, or what brought the patient to the doctor; the history of the present illness; past medical history including maintenance medications; family medical history for possible inheritable diseases; a personal and social history which can include risk factors such as smoking and sexual habits and exposure histories. Some specialties and subspecialties have additional history items, like an obstetric/gynecologic history or a psychiatric history.
After completing history taking, we take the vital signs and do a complete physical examination. Some specialties and subspecialties have additional exams, like an ophthalmologic exam for eye doctors, an internal exam for obstetrician/gynecologists, and a detailed skin exam for dermatologists. Following the complete history and physical examination, we then formulate our differential diagnoses—a list of possible diseases that may be causing the patient’s sickness. We do laboratory and imaging tests based on these possibilities and most of the time these give us a good idea of what the patient has and we can begin treatment. Unfortunately, this isn’t always the case.
If the primary doctor can’t figure out what is wrong with a patient, the next step is to refer to a specialist or a subspecialist. Many times, the chief complaint can at least narrow down the possibilities to a specific organ system or to a possible cause. For instance, someone with uncontrolled seizures will probably be referred to a neurologist. Someone with a heart failure symptoms will be sent to a cardiologist. As an infectious diseases doctor, one of the most common diagnostic dilemmas referred to me is the very descriptively named “fever of unknown origin” or FUO.
A fever of unknown origin is a fever that has lasts more than two weeks with no clear source despite a reasonable attempt at working up the case. The reason for the two-week time frame is because a lot of fevers from infection are caused by viruses which are difficult to diagnose with the usual tools but usually get better on their own in two weeks. Some doctors prior to referring to a subspecialist will go ahead and start some antibiotics for a possible infection but there is no adequate response. This trial of medication is known as “empiric” treatment which represents their best hypothesis as to what the patient may have in terms of an infection. A “reasonable” workup can also vary among doctors and the capabilities of each laboratory or hospital, and so we sometimes get patients with very extensive (and very expensive) workups which haven’t found anything, while some come to us with very rudimentary laboratory test results.
Diagnostic dilemmas such as FUOs are particularly distressing for patients since they feel like they have no control over what is happening. We usually admit FUO patients to the hospital to expedite their workup. Among the causes of FUOs are infection, rheumatologic diseases (such as lupus), cancer (some are notorious for causing fevers), and hypersensitivity (e.g., drug fever). We do workups that help us narrow these broader categories. For instance, one set of laboratory tests we typically look at are inflammatory markers such as highly sensitive C-reactive protein (hsCRP) and the erythrocyte sedimentation rate (ESR). If these are elevated, it is more likely an infectious, rheumatologic, or hypersensitivity cause, while normal hsCRP and ESR suggest cancer or some other non-inflammatory cause. Ten percent of FUOs never end up with a firm diagnosis, while some only have a partial diagnosis. Luckily, some FUOs resolve on their own even without treatment. The most important goal for doctors is to make sure there is nothing that is missed that could seriously jeopardize the patient’s health.
In the Philippines, one of the most common causes of FUO is tuberculosis. Most lay people are familiar with tuberculosis in the lungs, but almost all parts of the body can be infected with tuberculosis even without lung manifestations. It can be difficult to get a proper specimen to prove that someone has tuberculosis outside the lungs. For instance, someone with tuberculosis of the liver may show some suggestive findings on CT-scan, such as enlarged lymph nodes in the vicinity of the liver or some ill-defined nodules in the liver. Getting a tissue sample can be invasive and so sometimes we do what we call a therapeutic trial of tuberculosis medications. This can be nerve-wracking because tuberculosis of the liver usually elevates the liver enzymes AST and ALT, but the medications themselves are processed in the liver and so it can be risky. The decision to proceed is what distinguishes clinical medicine from other hard sciences. Even without a definitive diagnosis, a potentially toxic treatment is started based on a reasonable conclusion taking into account the pattern of disease and supporting lab tests.
Most patients with FUO from tuberculosis start to feel better in about five days, with the fever eventually going away and the liver enzymes normalizing in a week or two. A good response is enough to make the diagnosis, and treatment can be completed with close monitoring.
Many people are familiar with the TV show House which features a very cranky but brilliant doctor along with his long-suffering team who can diagnose the most obscure diseases with pattern recognition. While entertaining, a real Dr. House would not remain in practice for very long.
The best way to resolve challenging diagnostic dilemmas is through a close partnership between the doctor and the patient, and this requires a lot of empathy and good rapport. Doctors need to be honest to patients about the limits of their knowledge, and should be willing to team up with other specialists if they aren’t sure of the next steps.
Making timely treatment decisions even with incomplete information can sometimes mean the difference between life and death, and all these decisions need to be made in the best interest of the patient’s health. Doctors don’t always have the answers, but they should always take care of their patients.