Proteinuria in Teenagers: Causes and Concerns

Dear Doctor, why do I easily have proteinuria?

Hello, I am a 17-year-old male.
I have been experiencing proteinuria (+~++) for about a year.
During this time, I have visited three major hospitals for diagnosis.
I have undergone blood tests to assess kidney function and a 24-hour urine test (spaced about two months apart).
The doctors indicated that the tests showed no issues and that my kidneys were fine, so I was advised to continue monitoring the proteinuria.
Later, I went to a laboratory for follow-up tests and found that the proteinuria had increased to 3+.
Further examinations also showed no problems, and eventually, the proteinuria disappeared.
Recently, I have been experiencing intermittent lower back pain (which I have not had before) and sometimes feel fatigued at school.
The discomfort feels more than just muscle pain, as I can press on certain points that are uncomfortable (but my blood pressure is normal, my BMI is normal, I have no fever or cold sweats, and I do not appear to have edema).
Therefore, I tested for proteinuria again, and the result was 2+, with a slight increase in white blood cells.
I have arranged to have blood tests next week, and if there are any issues, I will consult a nephrologist at a major hospital.
I would like to ask the doctor, at my age, is it possible to have isolated proteinuria? Why is it that most others do not experience this, and it seems to be only me? (In my class, it appears to be just me; according to the health office statistics, there are fewer than five cases in the entire high school.) Does this indicate that I might have a congenital kidney issue?

Shen. Shen, 10~19 year old female. Ask Date: 2013/10/12

Dr. Huang Yaoxuan reply Internal Medicine

Hello, I am a nephrologist who relies on "tests (blood and urine tests, X-rays)" and "machines (dialysis machines)" to make a living...
This is purely a joke (any resemblance is coincidental), but it does highlight the concerns of nephrologists and patients with kidney disease.
Most chronic kidney diseases progress silently and asymptomatically, so physicians need to utilize various tests and follow-ups to inform patients about the current state of their kidneys.
These tests include screening for "urinary protein." Here are two points I would like to share with you, hoping they will be helpful:
1.
There are several methods for urinary protein testing, including "qualitative (using dipstick tests on a single urine sample, which is what you referred to with the several plus signs)" and "quantitative (including the concentration of urinary protein in a single urine sample, measured in mg/dL, and the total urinary protein over 24 hours, measured in mg/day, or the calculated 24-hour urinary protein amount, measured in mg/g or mg/day)." The total urinary protein over 24 hours or the calculated 24-hour urinary protein amount is generally more accurate and clinically significant, although it is more expensive.
Therefore, health insurance typically starts with dipstick testing and only conducts the more expensive 24-hour urinary protein test if there are issues (nowadays, the calculated 24-hour urinary protein amount can be simulated with just one urine sample).
2.
Urinary protein can be "interfered with" by several factors, such as: (1) The concentration of urinary protein fluctuates throughout a 24-hour period, and certain factors can suddenly increase urinary protein levels, such as exercise, changes in posture, or consuming a large amount of protein in a short time (like having a big meal).
In these cases, qualitative screening may show several plus signs, while the 24-hour urinary protein amount might be normal.
(2) Another common interfering factor is urinary tract infections or hematuria, as infectious agents and blood in the urine contain proteins, leading to the detection of "urinary protein" that is not caused by kidney issues.
Therefore, I also perform a routine urinalysis to rule out hematuria or infection.
In conclusion, the final statement is simple: "If there are issues, definitely go to a major hospital's nephrology department for consultation."

Reply Date: 2013/10/12

More Info

Proteinuria, or the presence of excess protein in the urine, can be a concerning finding, especially in teenagers like yourself. It’s understandable to feel anxious about this condition, particularly when you’ve undergone multiple tests and evaluations without a clear diagnosis. Let’s explore the potential causes of proteinuria in adolescents, its implications, and why it might be occurring in your case.

Causes of Proteinuria in Teenagers
1. Transient Proteinuria: This is the most common type of proteinuria seen in adolescents and can occur due to temporary factors such as dehydration, intense physical activity, fever, or stress. In many cases, this type of proteinuria resolves on its own without any long-term implications.

2. Orthostatic Proteinuria: This condition occurs when protein is excreted in the urine while standing but not when lying down. It is often benign and more common in adolescents. If this is the case, your protein levels may fluctuate based on your posture.

3. Underlying Medical Conditions: While transient and orthostatic proteinuria are common, persistent proteinuria may indicate underlying health issues. Conditions such as glomerulonephritis, diabetes, or hypertension can lead to proteinuria. However, given that your kidney function tests and 24-hour urine tests have returned normal results, serious conditions may be less likely.

4. Infections: Urinary tract infections (UTIs) can also cause proteinuria, along with other symptoms such as increased white blood cells in the urine. If you have had any recent infections, this could explain the proteinuria.

Concerns and Implications
The presence of protein in the urine can be a marker of kidney health. In your case, the fact that you have undergone multiple tests and the results have consistently shown normal kidney function is reassuring. It suggests that your kidneys are likely functioning well despite the proteinuria.
Your symptoms of intermittent back pain and fatigue could be related to various factors, including muscle strain, stress, or even anxiety about your health. It’s essential to discuss these symptoms with your healthcare provider, as they may help in understanding the overall picture of your health.

Why You Might Be Experiencing This
It’s not uncommon for some individuals to experience proteinuria while others do not. Factors such as genetics, lifestyle, and even body composition can play a role. It’s also important to note that proteinuria can be influenced by diet and hydration status. If you have been consuming a high-protein diet or have been dehydrated, this could contribute to the presence of protein in your urine.

Conclusion
In summary, while the presence of protein in your urine can be concerning, it is often benign, especially in adolescents. The fact that your kidney function tests are normal is a positive sign. It’s crucial to continue monitoring your condition with your healthcare provider, who may recommend further testing if necessary.
If you experience any new symptoms or if your protein levels remain elevated, it’s essential to follow up with a nephrologist or your primary care physician for further evaluation. They can provide you with personalized advice and reassurance based on your specific health situation. Remember, maintaining a healthy lifestyle, staying hydrated, and managing stress can also contribute positively to your overall health.

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