You’re going through life feeling pretty good, but how healthy are you really?

You’ve got a tan. Nice.

You can do 20 push-ups. Even better.

But how do you know that some internal part of you — a lesser organ, say — hasn’t begun to malfunction?

You don’t know ... maybe not until it’s too late.

This is why I get annual physicals. I want to be scrutinized by someone who is trained to identify bad stuff.

My physical is next week. To make the visit count for something, I submitted to lab tests first.

You can’t fake out lab results. Blood and urine do not lie.

As lab day approached, I got jittery. I’ve had blood-sugar issues over the years. For a time I had high cholesterol.

Each condition prompted lifestyle reforms. I began laying off the doughnuts in the Register lunchroom. At home, no more nightly slabs of angel food cake with vanilla ice cream for me.

Have there been relapses? Of course there have been relapses.

The real question is: Will the lab results reveal my cheating.

I put off the tests as long as possible. Complete fasting for 12 hours — no food, no drinks worth drinking — ruins the night before and the morning of.

As I left for the lab at 6:45 a.m., Cheryl, who was feasting on a bowl of cereal topped with blueberries and raspberries from our backyard, wished me luck. She may even have toasted me with her mug of fresh-brewed coffee.

The woman at the lab was crisply efficient. Proud of my veins, I told her she could have either arm.

Still, I winced in anticipation of the needle. I’ve had a few bad pokes over the years. I don’t like the idea of being pierced.

This time the draw went just fine. The tech filled three vials with my red essence. I was counting, not looking. I never look.

After wrapping my arm, the tech handed me my cup. When you’re done, put it over there, she said.

I said fine, but things weren’t. I doubted I could pee.

I’d awakened that morning knowing I’d be donating urine in about an hour, but I’d gone ahead and emptied my bladder anyway. I figured there would be a line at the lab, giving me an extra half hour to generate more.

There wasn’t a line. I’d walked right in.

So, here I was — showtime! — in a depleted state.

Standing in the lab bathroom, cup in hand, I considered my options. Do I gulp water from the sink faucet? Beg for a sip of coffee? Will my bladder awaken before the next customer knocks?

This anxiety was a good thing. Feeling the pressure, my brain began spewing out pee-inducing hormones. Suddenly I sensed possibilities.

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Can you get accurate lab results from a quarter inch of concentrated urine?

Such a pitiful amount. Would the testing equipment even recognize my sample as human?

My results became available online last week. I printed them for Cheryl, who is not technically a medical doctor but often acts as one.

The three-page printout included more than 40 assessments. My cholesterol? Not bad. Blood-sugar? In my view, acceptable.

As someone who’s been radiated for prostate cancer, I consider my PSA level a biggie. This year’s score: Great.

Dozens of other test results meant nothing to either one of us.

The specific gravity of my urine was 1.022. Is that good for an earthling?

My mean corpuscular volume was a little high. Does anyone know what this means?

My sit-down with my doctor is this coming week. He’ll ask how I’m doing and I’ll say fine, just fine. All things considered.

Do I still jog? I’ll assure him that I still do.

Then we’ll go over those mostly inscrutable lab results.

I’m not sure you can trust my urine numbers, I intend to say. I gave under duress.

Kevin can be reached at 707-256-2217 or Napa Valley Register, 1615 Soscol Ave., Napa, 94559, or