Published: November 19, 2023 | 4 mins read
Low Diuresis Impact on Kidney Stone Formation
Low diuresis simply means low urine volume, and it is a significant risk factor for kidney stones. When you produce low urine output, stone-forming materials sit longer in your kidneys. And the longer they stay in your kidneys, the more likely they bind together to form stones.
How does low diuresis affect kidney stones?
Low urine volume is a risk factor for kidney stones for two reasons.
The first reason deals with urine supersaturation. Supersaturation means there are excess particles that can no longer dissolve. If urine volume is low, stone-forming materials, such as oxalates, may supersaturate the urine. This becomes a problem because oxalates will bind with calcium ions in the urine, forming calcium oxalate stones.
For example, you had a cup of spinach for dinner. A cup of spinach (50–100 g) contains around 500–1,000 mg of oxalate. As a result, a significant amount of oxalate will be swimming in your urine.
So if you want to lessen your risk, avoid oxalates. Since calcium is essential for the body, don’t limit calcium. The recommended daily calcium intake is 1,200 mg, while <80 mg for oxalates (<50 mg for best results).
Second, the less you urinate, the more time you allow for particles to stick together. And this is true for most stone types.
Stones can take time to form. So, the more frequently you release these particles out of your system through urination, the lower the chance they will form into kidney stones.
What type of kidney stones will form if urine volume is low?
Low urine volume is a risk factor for many kidney stone types if not all.
For instance, low diuresis favors the formation of some calcium oxalate stone types. If you form stones that look like these, low diuresis may be contributing to their formation:
Mixed stones made of uric acid and calcium oxalates, though they are very rare, may also form under this condition. Here’s what these stones will look like:
Conditions That Can Lead To Low Diuresis
Underlying diseases, injuries, or certain medications can cause low urine flow.
The most common reason is improper hydration (<96 oz.). But if you are properly hydrated and still produce low urine, conditions surrounding the urinary system would be our next prospects. These include infections, prostate enlargement, prostate cancer, chronic kidney diseases, etc. If you have these issues that block urine flow, you may suffer from low diuresis.
Having heart or lung conditions that impede the blood flow to the kidneys also lowers urine output.
Undergoing surgeries that could bring a “state of shock” or trauma to the body could also be a culprit. When blood flow is disturbed, or there is blood loss, urine output is reduced. That’s because our body has an instinct of conserving or maintaining fluid balance, which means we hold onto water and don’t excrete it through our urine.
Certain medications can also be the cause of your low urination. These medications include:
- Non-Steroidal Inflammatory Drugs or NSAIDs (for pain relief)
- Antibiotics (esp. the aminoglycoside class)
- Contrast agents (given before a CT to better picture the insides of the body)
- Chemotherapy drugs (used in cancer treatments)
- Immunosuppressants (used to “calm” the body and not reject foreign objects)
If you aren’t sure of the real cause of why you are urinating less, speak with your doctor. They have the appropriate tools to better assess your situation.
How to address low urine output?
Low urine volume mostly happens because you drink less than what is necessary.
The American Urological Association suggests that healthy urine output should be about 2.5 liters per day (~80 oz). To get to this output level, you will need to drink about 3 liters or 6-8 large glasses (16oz) of water. If you are active and sweat a lot, you should drink even more than this.
To learn more about proper hydration habits and for a few tips on how to increase your daily water intake, read our blog on Hydration.