Ask a doctor on the topic of Urology

Kidney stone and high-protein diet

November 2, 2011 | 20,00 EUR | answered by Dr. med. Ralf Berg

Hello!

Background:

Nine years ago, I had a severe kidney colic. While I was in the emergency room, a kidney stone passed during urination. Unfortunately, it disappeared in the toilet and could not be further examined. Since then, I have been symptom-free without any follow-up treatment.

Last weekend, I experienced another colic. This occurred after jogging. The pain was bearable and lasted for about 1 hour. My urologist found traces of blood in my urine. The ultrasound was inconclusive as the "kidney funnels were dilated". Next, I have a contrast X-ray scheduled. One day after jogging again, I had another (slightly milder) colic. So far, I haven't noticed any passage during urination.

About four months ago, I completely changed my habits due to overweight and unhealthy eating. I drink about 3 liters of still water per day and have a high protein, relatively low carbohydrate diet (lost 12 kg and feeling great). My main sources of protein are fish, chicken, low-fat yogurt, cottage cheese, and 2-3 protein shakes made from high-quality protein powder per day. Carbohydrates come from whole grains and vegetables. I run 2-3 times a week and go to the gym 2-3 times a week.

Now my questions:

1. Could it be that the colic only occurs with certain types of movement (jogging)? Should I intentionally "provoke" the colic through exercise or wait for the results of the X-ray?

2. Is it possible that, even if I remain symptom-free after exercise, the stone has passed unnoticed?

3. What does it mean that the "funnels were dilated" during the ultrasound and what is the cause?

4. How long does it take for a kidney stone to form? I fear that my high protein diet change four months ago could be the cause, or is the cause more likely due to years of poor nutrition before?

5. Can modern, high-quality protein supplements actually promote the formation of kidney stones? I thought only purines found in animal protein sources were "dangerous". My supplements mainly consist of whey and soy protein.

6. If 5. is true, is it advisable to use alternative protein sources, and which ones? Despite significant weight loss, I have retained very little muscle mass, which I attribute to my training and protein intake. I want to continue to maintain or build muscle. Besides plant proteins, would amino acid concentrates be an option, or could they also promote kidney stones?

Of course, I still have a detailed discussion scheduled with my urologist, as he was too busy last time I visited without an appointment. Nonetheless, it would be great to get answers to these questions beforehand.

Thank you!

Dr. med. Ralf Berg

Dear patient,

I would like to start from the end. The most likely cause of stone formation in your case is probably due to your significant weight loss. During the breakdown of cells, large amounts of uric acid and oxalate are produced. These can lead to gout attacks or stone formation.

Regarding your question number 4, the cause lies in years of poor nutrition. The speed at which a stone can grow is not exactly known and depends on the composition of the bile fluid and liver function. However, there are many reports of stone formation occurring shortly (4 weeks to 2-3 months) after a radical change in diet resulting in weight loss. In terms of proteins, it is important to note: 1. Whey (derived from cows) is considered an animal protein source. 2. It is true that not only amino acids (which can be converted to oxalic acid) but also purines can lead to stone formation. 3. Even plant-based (soy) products contain a nucleus where these purines (although in much lower quantities) can be found.

In terms of quantity, however, this is negligible compared to the proportion resulting from cell breakdown and weight loss.

Regarding question 3 about blocked funnels: due to the passage of a stone, injuries occur in the ureter (hence the presence of blood) and subsequently, swelling occurs, causing the urine to drip less quickly. A skilled urologist will notice or suspect this when the pyelonephric funnels appear somewhat "blocked". However, this is not a real blockage with extension to the renal pelvis! Therefore, especially after a stone passage, this is normal and simply an indication that it has occurred.

As for questions 1 and 2: It is not only possible but often the case that a stone is passed through exercise. I would advise you not to try to provoke colic by jogging but rather wait to see the results of the X-ray. Then you can resume your exercise routine. In summary, you should take it a bit slower now. It's great that you have made a lifestyle change, but you should now take a step back. Even if your weight remains stable for a while, you should take this time to allow your kidney to recover and dispose of the "cellular debris".

Best regards,
Dr. R. Berg