Prologue: So That Even Non-Doctors Have Nothing to Fear

I take warfarin. It’s a blood thinner—an anticoagulant—that keeps clots from forming. Clots (basically, blood that’s solidified) can be life-saving when they seal a cut, but inside a vessel they can block flow and turn deadly.

One common reason to use warfarin is a mechanical heart valve. Heart valves are like one-way doors: they open to let blood move forward, then close to prevent backward flow. The left side of the heart pushes oxygen-rich blood to the body; the right side sends blood to the lungs to pick up oxygen. For that circuit to work, blood must travel in one direction, and valves enforce that.

When a valve is badly diseased, surgeons sometimes replace it with a mechanical device made of ceramics or metal alloys. Those valves do the job, but they change local blood flow and raise the risk of clotting. Warfarin reduces that risk by making the blood slower to clot. It’s standard therapy after valve replacement.

In the winter of my first year of high school I had my mitral valve replaced—the valve on the heart’s left side that prevents backflow into the atrium. I’ve taken warfarin every night since.

Because warfarin’s effect varies, the blood’s tendency to clot has to be checked regularly. We summarize that with the INR (international normalized ratio). A typical INR is 1.0; mine needs to sit around 2–3. In other words, my blood should clot two to three times more slowly than average.

Warfarin is a finicky partner. The same dose can act differently depending on your health that week. A single drink can push the number around. Food matters too, especially anything rich in vitamin K, which counteracts warfarin. Think spinach and other leafy greens; in Korea, cheonggukjang—a strong, fermented soybean stew akin to Japanese natto—is loaded with vitamin K and best avoided if you’re on warfarin.

Because everyday life can nudge the INR up or down, people like me get blood tests at least every three months to be sure the number stays in range. Mine wanders a bit but usually hovers where it should.

That day was my routine lab day. The blood draw takes a minute; the machine needs about an hour. So I always show up an hour before my clinic slot, get my sample taken, then wait outside the exam room. If results aren’t back when my name is called, my turn gets bumped until they arrive.

The nurse called me in. Behind the desk sat a professor with kind, white eyebrows—he’d taken over my care when my original pediatric cardiologist neared retirement. After years of three-monthly visits we were familiar enough to recognize each other on the street. I bowed, slid onto the low, round exam stool, and settled in for an ordinary check-in.

Until it wasn’t. He clicked my name, opened the labs, and suddenly leaned closer to the monitor. I didn’t need him to spell it out. That day’s INR was over 7.

My target is 2–3. A seven means my blood’s clotting ability is severely suppressed. At that level, even bumping a hip on a desk could trigger bleeding I couldn’t stop. The professor stayed calm but visibly tightened. My own fear was different in kind. It was happening to me. Doctors and patients may share the goal of recovery, but the risk—and the fear of what happens if things go wrong—lands squarely on the patient’s body.

I tried to think through causes. I hadn’t changed my routine, I’d taken my meds, I wasn’t bruising more than usual. But the number on the screen told another story. The professor sent me to the ER.

I walked—carefully. If your INR might be seven, you don’t jog to the emergency department. That was the first time I learned how slowly time moves in an ER when you might be the bomb. Of course the staff were triaging; I knew that as a physician. But the ER you know as a doctor and the ER you endure as a patient are two different planets.

Eventually I got a bed. A junior doctor arrived, asked sensible questions, typed into the chart, thought for a moment, then proposed vitamin K to reverse the anticoagulation. I said:

“If there’s a real chance the first test was wrong, giving vitamin K right now might not be our best move.”

He frowned.

“In that case, there’s nothing I can do for you right now.”

Strictly speaking, he wasn’t wrong. If we weren’t going to treat, there wasn’t much to do. So I offered this:

“The repeat lab will be back in about an hour. Let’s decide when we see it.”

He agreed. An hour later he returned with the new result: INR 2.7—perfectly within my target range.

Warfarin’s half-life is about a day or two. An INR cannot fall from 7 to 2.7 in an hour without intervention. At least one test was wrong—possibly both.

I sat with that. I wanted to keep trusting this hospital, as I had for years. But two mutually exclusive results, an hour apart, forced a question: Can I still trust this system? There was only one honest way to answer—find out why it happened, and make sure it wouldn’t happen again.

That isn’t easy for any patient. Filing a formal complaint risks souring a relationship you rely on—especially when, like me, you have an uncommon condition and don’t have many alternatives.

But precisely because this is the one place I depend on, there was no other choice. I submitted a complaint.

The internal review found the cause quickly: the lab analyzer hadn’t been properly calibrated before use. Imagine weighing something on a scale that wasn’t zeroed—the reading is off from the start. The responsibility lay with the clinical laboratory team.

What came next disappointed me more than the error. The lab physician tried to minimize it—“These things happen,” “No harm done in the end”—the kinds of lines no patient can accept. I tried to understand the impulse. Perhaps he feared I’d seize on any misstep to make trouble. But often a patient’s persistence is a reaction to a stonewall, not a cause of it.

A few days later he changed tack. He acknowledged the mistake and apologized. I don’t know what moved him—worry about escalation, sensing I wasn’t out for blood, or all of the above. Whatever the reason, the apology helped both of us.

I told him I wasn’t looking to assign more blame for what had already happened. But stopping there would miss the point. I looked him in the eye and said:

“I accept your apology. But there’s a more urgent task than apologizing to me. Anyone who had labs run around the same time could have received a bad result. Please find them quickly and make sure they’re safe.”

Only then did I add, for context:

“I’m a physician. That’s likely why I could navigate this. If this had happened to someone without medical training, it could have ended very differently. You already know this. Please make sure, going forward, that every patient gets the attention you’d want for your own family—so this doesn’t happen again.”

He paused, nodded, and said quietly, “Yes. We’ll do that.”

They did. Three months later, my usual professor saw me with his normal calm, and life returned to routine. But the ER visit left me with a question I refuse to forget:

Most people are not doctors. Far fewer have a doctor in the family. In health care, that majority should not be at a disadvantage—because wanting to be healthy is a basic human need and right.

Since then, when I see patients I ask myself two things: Would I do this if the patient were my family? and If I were the patient, would I feel safe and respected? When I someday look back on my years in medicine, I want to answer those questions yes, without hesitation.

So that even non-doctors have nothing to fear.