Kidneys cannot make Struvite. It is bacteria that actually make it. And, not all bacteria, either. It takes bacteria that normally thrives in the soil. These special bacteria produce the kidney stone named Struvite after Heinrich Christian Gottfried von Struve (de) (1772–1851).
Here’s a brief outline of how it works. Animals deposit urea (“H2N” illustrated on the left in the above figure) all over the planet when they urinate. Plants cannot use it.
Like oxygen, nitrogen is essential for life, yet dangerous. It is integral to proteins, DNA and RNA. As these molecules are broken down and remade, some of their nitrogen slips by and can form poisonous compounds unless caught up in safe waste products. Of these, the main one, urea, contains 2 nitrogen atoms bound to a single carbon atom (‘C’ in the picture above).
Uric acid contains 4 nitrogen atoms (illustrated below). Birds and reptiles excrete most of their nitrogen as uric acid; mammals (like us) excrete nitrogen mainly as urea.
As the animals of the world urinate on the soil, their urea brings nitrogen to plant roots, but the plants cannot use it. They cannot release the nitrogens from the carbon atom that holds them. Those soil bacteria that make struvite crystals have an enzyme, called urease, which can release the nitrogen for plants to use as their nitrogen supply. So, soil bacteria with urease maintain the nitrogen cycle of the earth.
As the bacteria release nitrogen from its carbon in urea, the nitrogen takes up a proton making ammonia (NH3). Ammonia is a powerful alkali and takes up another proton.
As it does so, the working bacteria surround themselves with spheres of very alkaline fluid enriched with ammonium ion (NH4) that carries one positive charge. Soil magnesium (an atom with two positive charges) and phosphate without all of its protons (an ion with three negative charges) spontaneously form their triple salt: three negative phosphate charges, two positive from magnesium, one positive from NH4).
The crystals anchor the bacteria and help create a porous nitrogen rich soil good for plants to grow in.
Because urine is filled with urea, soil bacteria that get into the urinary tract can break it down to ammonia and create struvite from the magnesium and phosphate urine always contains. Soil bacteria enter our system because we eat them with foods that are not cooked and become part of the intestinal bacterial population from an early age. In us and around us, they find a way into the urinary system, especially in women whose shorter urethra makes entry easier. No matter how skillfully used, any instrument put into the bladder can carry our personal soil bacteria with it.
Since these soil bacteria live among molds and fungi, they easily mount resistances to antibiotics. So, antibiotics given for a urinary tract infection will tend to kill sensitive bacteria and select out those that can resist them.
Soil bacteria can produce Struvite stones de novo, or infect Calcium stones to produce a mixed stone. Either way, Struvite stones are infected by their very nature. They can become huge. Their bacteria can injure the kidneys, even enter the bloodstream and cause sepsis.
Treatment is a mix of thoughtful surgery and selection of antibiotics after such surgery to kill bacteria that remain. If the stones are a mixture of struvite and calcium crystals, new calcium stones need to be prevented.
*Source: Dr. Frederic Coe - University of Chicago
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