Glomerular fluid, the fluid which is filtered into the glomeruli, is rich in electrolytes, minerals and other substances. These substances can
precipitate (settle out of the urine) in the Urinary tract, forming stones (or calculi). These form most often, in the renal pelvis and the bladder.
The substances involved are, most commonly, oxylates, phosphates and uric acid. Renal calculi often consist of more than one of
these substances, deposited in layers, within a framework or scaffolding of mucoprotein.
When allowed to lie in the Urinary tract,
calculi may slowly increase in size due to further precipitation of the solutes. In this way, stones can ‘grow’, becoming larger.
For instance, very small stones, sometimes known as gravel (measuring less than 1 mm in diameter) can form in the smaller tubes of the Urinary
tract such as the collecting tubules. They then pass into the pelvis of the kidney where they slowly increase in size, eventually forming a
more substantial stone which can then be visible under X- ray.
About 90 % of kidney stones can be visualised using X-rays, whereas 90
% of gallstones do not show up using this method of investigation. This is due to the difference in composition of the stones. X-rays show up
stones which contain calcium, or similar ‘heavy’ atoms. Calcium is a major constituent of kidney stones, whereas most gallstones contain large
amounts of ‘soft‘ cholesterol.
The outcome of these stones depend on the size.
Small stones present in the kidneys may pass through the ureter and then, into the bladder to be excreted. This obviously gets rid
of the stone but can cause damage to the narrow structures of both the ureter and urethra as it passes through the Urinary tract.
This passage is usually accompanied by a great deal of pain and the presence of blood in the urine. Other features include fever
(as infection enters the blood) and vomiting (due to pain and the presence of toxins in the blood).
If these small stones pass into
the ureter, but become ‘stuck’, obstruction to the flow of urine in the kidney occurs. This can lead to distension of the kidneys,
with severe pain and fever. If left unattended, an obstructed kidney may suffer permanent and irreversible damage, leading to renal
Sometimes, one large stone may form, slowly growing in the renal pelvis over a number of years. A single large
stone will be the out- come, but this may fill the whole of the renal pelvis, forming a ‘coral-like’ stone called a ‘staghorn calculus’.
As the stone is so extensive, severe obstruction of the kidney occurs giving rise to renal impairment and renal failure.
With such a badly diseased kidney, recurrent bacterial infection and the presence of stagnant urine provide a very favourable
environment for more stones to form.
The formation of stones is essentially the result of a series of chemical reactions. There are a number of factors which can encourage and speed up these reactions, predisposing to the formation of calculi.
The incidence of kidney stones is far higher during the hot summer months. The loss of water through sweat during this time of the year, especially during exercises such as jogging, increases the secretion of ADH. This forces the kidneys to conserve water by increasing the reabsorption of water from the tubules of the nephrons, resulting in a highly concentrated urine. This in turn, creates a more favourable environment for the solutes present in urine to precipitate out of solution, forming stones.
pH of Urine
Change in the pH (the acidity or alkalinity) of urine can cause substances to precipitate out of solution. Normal urine is acidic, but when it becomes alkaline, substances such as phosphates are precipitated more readily.
Infection by the organism Proteus causes an alkaline urine to be produced. Staghorn calculi are most often caused because of Proteus infections of the urine. Even if the conditions are right for precipitation to take place, stones will not form unless there is a ‘focus’ for the solutes to ‘cling’ onto. Bacteria present in the Urinary tract can often provide this by acting as the ‘seed’ around which the solute is deposited.
In poorly hydrated kidneys, substances such as uric acid, oxalates and phosphates are not flushed through the urinary tract efficiently
increasing the chance of developing kidney stones.
Drinking enough water can help reduce this tendency as can taking sufficient
magnesium to allow calcium to absorb correctly, as precipitated calcium is another ingredient of stones. It is important to keep uric acid
at its normal level. Excessive amounts lead to the formation of crystal deposits in the kidneys which may then go on to form kidney stones.
These deposits may also be found in body tissue, causing a generally toxic environment. When found in joints, uric acid deposits
may giverise to arthritic conditions.
Stinging Nettle increases urination.
It helps to flush out materials that may develop into kidney stones, and can be combined very well with the traditional diuretic plants,
dandelion and goldenrod.
- Increases urine flow and helps the kidneys get rid of acids
- Prevents kidney stones and gravel