No kidney function in routine physical examination?

The routine basic physical examinations that cost 100 to 1,000 yuan for most people do not cover a complete renal function assessment. The "two/three items of kidney function" that everyone often sees cannot screen out early kidney damage at all.

I was still feeling this when I was reading a report for my distant cousin a while ago - a 32-year-old Internet backend who stays up late all the time drinking iced Coke. His creatinine was still within the normal range during the physical examination last year. In the spring of this year, his feet were swollen for half a month and could not go away. After going to the nephrology department for a checkup, he was diagnosed with stage 3 chronic kidney disease, and his glomerular filtration rate was only half of normal people. After digging through last year's physical examination report, I discovered that in his 1,200-yuan annual physical examination package, "kidney function" only included blood creatinine and urea nitrogen. Even the most basic urine routine was included in the "optional extras", not to mention urinary microalbumin and cystatin C.

Many people's understanding of "kidney function test" is inherently biased, which is also the core reason why this issue has always been controversial. Many people think that taking a tube of blood to check creatinine, if the value is within the reference value, means that there is no problem with the kidneys. Even the "renal function tests" promoted by many medical examination institutions are based on this concept. However, in the clinical standards of nephrology, a complete assessment of renal function must cover at least three dimensions: first, urine test (preferably morning urine routine, plus urine microalbumin/creatinine ratio to see if there is early protein leakage); second, blood test (except for Creatinine, urea nitrogen, and cystatin C are also required, and the glomerular filtration rate (eGFR) must be estimated based on age, gender, and weight. The third is urinary tract ultrasound to see if there are any abnormalities in the size and shape of the kidneys, and whether there are any problems such as stones and hydrops that may damage kidney function. Only when these three things are put together can the kidney function be truly checked.

There are very few routine basic physical examinations on the market today that can cover all three. Either blood creatinine and urea nitrogen are only tested, or the urine routine only checks a few key indicators for you. If urine protein is positive, you will be followed up. Few medical examination institutions will take the initiative to include eGFR in the report - after all, creatinine is in the reference value. If the report says "normal kidney function", it will look good and no one will come to trouble you.

Of course, not all routine physical examinations are like this. If your company's benefits are particularly good and the annual physical examination budget is more than 3,000, then these items will most likely be covered. However, for most ordinary people, the basic packages purchased by the company we participate in, or the 100-yuan entry-level package we buy cheaply, the "kidney function" in such packages are basically discounted.

I have been in the Nephrology Department for 6 years, and more than 80% of the patients with early-stage kidney disease aged 20-40 years old have had routine physical examinations within half a year, and the report at that time said everything was normal. Last week, a 28-year-old girl came for a pre-pregnancy check-up and was found to have 2+ urine protein. She had just had the company's annual physical examination three months ago, and her creatinine was 72 μmol/L. Her kidney function was normal as written on the report. I calculated her eGFR, which was only 76 ml/min·1.73 m², which is more than 20 points lower than the average for women of the same age. She already has a mild decline in kidney function. If it were discovered half a year later, it might affect pregnancy preparations.

Don’t be too anxious. If you don’t have high blood pressure, diabetes, gout, obesity, or a family history of kidney disease, and don’t take painkillers or folk remedies all year round, and take the initiative to do a 10-yuan urine routine every two years, you can basically screen out most problems. If you are in a high-risk group, listen to my advice. Don’t wait for the results of routine physical examinations. Spend more than a hundred yuan every year on yourself, plus a morning urine urine microalbumin/creatinine ratio, plus a complete kidney function test containing cystatin C, and let the doctor help you calculate your eGFR. It will be much more useful than spending thousands of dollars on those useless fancy screening projects.

By the way, don’t feel relieved when you see creatinine in the reference value. Especially girls who are very thin and don’t like to eat meat usually have low basic creatinine. For example, if the upper limit of the reference value is 73, and you find out 71, don’t think it’s okay if it is far from the upper limit. It only takes less than two minutes to find a doctor to calculate your eGFR. It can really avoid a lot of pitfalls.