"Healing Glands" Part 2 - The Kidneys
Within each kidney are located a million or more compact tubules - microscopic units called nephrons - and their associated blood vessels. Nephrons are responsible for the functions of the kidney, e.g. filtration of blood plasma, reabsorption and retention of useful materials from this filtrate and the excretion of a small volume of excess water, salt and potentially harmful substances such as ammonia and hydrogen ions (acid). The first part of these tubules is known as Bowman’s capsule which contains a dense tuft of capillaries, the Glomerulus in which the blood plasma is filtered.
About a quarter of the cardiac output at rest is received by the kidneys, which is equivalent to about one and a quarter litres per minute or 1800 litres daily. Out of this only about a tenth or 180 litres is filtered into the tubules (approximately 7.5 litres per hour). This is known as the glomerular filtration rate. As only 1-2 litres of this fluid is excreted in the urine in any 24 hour period, it is clear that 178-179 litres are reabsorbed from the tubules and are diffused through the interstitial fluid into the peritubular capillaries. From here the retained fluid is delivered back to the main circulation by way of renal veins.
There are two mechanisms of filtration and reabsorption: active and passive. Active reabsorption involves the expenditure of chemical energy (ATP) to move dissolved material such as sodium, potassium, glucose and amino acids from the tubular cells. Passive reabsorption does not involve ATP breakdown and is done in three ways:
1. Diffusion (e.g. urea moves from an area of high concentration (tubules) to lower concentration (interstitial fluid).
2. Ionic attraction (e.g. as positively charged sodium ions are actively reabsorbed, so negatively charged chloride ions are attracted and follow).
3. Osmosis (e.g. water moves towards the areas of high sodium ion concentration - that which has been previously reabsorbed into interstitial fluid).
Reabsorption is affected by the action of two hormones, aldosterone and anti-diuretic hormone (vasopressin). Aldosterone, secreted by the adrenals, accelerates the active reabsorption of sodium, and increases the passive reabsorption of chloride, bicarbonate and water. Vasopressin from the posterior pituitary enlarges the pores of the distal convoluted tubules and collecting ducts, allowing water molecules to be passively reabsorbed by osmosis at a faster rate. In the absence of vasopressin, much more urine than normal is excreted.
Finally, active secretion of toxic substances or materials excess to the body’s needs can occur, transporting ammonia, hydrogen ions and potassium from the exterior (interstitial fluid) to the interior of the tubules.
Kidneys & Exercise
The alterations in kidney function brought on by exercise are highly variable from day to day for an individual and also between individuals and relate to:
1. Differences in physical fitness and atmospheric conditions, e.g. temperature.
2.Variations in the severity and duration of the exercise.
3. Difficulties in measuring and evaluating kidney function under different conditions etc.
Since kidney function obviously depends upon the amount of blood delivered to the nephrons, any change in renal blood flow during exercise must have a profound effect on the operation of the kidneys. For example, renal blood flow can be reduced by up to 65% during heavy exercise, but only when the heart rate is increased to about 135-140 beats per minute. Glomerular filtration rate, urine volume and excretion of urinary solutes are all affected during heavy exercise and these responses are important because of their contributions to :
1. Maintaining adequate blood flow to the working skeletal muscles.
2. Conserving body fluids needed for cooling by evaporation.
3. The control of pH in body fluids.
After exercise has ceased, most body functions return to normal resting values within an hour of recovery, but prolonged exercise may cause changes lasting up to 10 hours after exercise. Most of those substances which were excreted at reduced rates during exercise, for example sodium, chloride, magnesium, and creatine, show an initial increase in excretion for 30 minutes after exercise before resting excretion rates are reestablished. Urine volume increases and acid and ammonia excretion remains elevated after exercise for 30 minutes or longer until the lactic acid levels in the body are returned to normal levels.
For a more comprehensive explanation of the relationship between diet, urinary pH and the physiology of many kidney disorders, please refer to the textbook “Correlated Urinalysis” by Dr. M. T. Morter.
With ageing the function of the kidneys diminishes. A measure of kidney function is called the Creatinine Clearance Test. This test measures the capacity of the kidneys to clear creatinine, which is a waste product, from the blood and into the urine. By determining the creatinine concentration in the blood and the quantity eliminated in the urine in a 24 hour period, creatinine “clearance” can be calculated. There is a steep decline in this measure after the age of 30. At this age the clearance biomarker is just over 140. At age 50 it is at 125. At age 70 it is down to 110. It continues to drop steeply with further ageing. With ageing, protein is lost in the urine and the kidneys sustain a progressive scarring of the multiple small filtration sacs which purify the blood. This is what lowers creatinine clearance.
Other tests of the health of the kidneys may be indicated from the use of urinary Multistix. Kidney impairment may be apparent from positive readings on Glucose, Specific Gravity, Blood, Protein, Nitrites, and Leukocytes although these readings can be positive in a number of other health conditions.
The most common kidney disorder seen in everyday clinical practice is kidney stones. There are two classes of kidney stones. One class, which makes up nearly a half of all cases of urinary calculi, are composed of calcium phosphate, magnesium ammonium phosphate, calcium carbonate, or a mixture of all three. The other class are composed of calcium oxalate, uric acid or cystine. The former tend to form in alkaline urine, the latter tend to form in acid urine.
The general recommendations given to reduce the chances of stones forming are as follows:
1. Drink plenty of water. A high water intake provides for a high volume of urine which reduces the burden on the kidneys. There is also less of a chance of crystals forming out of the body fluids.
2. Eat a more vegetarian based diet. According to one observational study, vegetarians have a 50-60% decreased risk of stones. In another experimental study, it was found that a high animal protein intake of normal subjects increased their urinary excretion of calcium oxalate and uric acid, while reducing the consumption of animal protein, reduced their excretion.
3. Increase dietary fibre. In one observational study, fibre intake was lower in stone formers than in controls. In an experimental study, 24 grams of bran daily, lowered calcium excretion by 20-25% in 73% of stone formers.
4. Reduce sugar consumption. Several studies have linked sugar and refined carbohydrates with risk of forming kidney stones.
Stones & Nutrients
This nutrient is needed to metabolise oxalic acid. A deficiency could result in increased urinary oxalic acid and tendency to form calcium oxalate stones. Certain hyperoxaluric patients may benefit from supplementation.
Several studies suggest that a deficiency of this nutrient could promote formation of stones.
Many doctors are under the impression that large doses of vitamin C can cause kidney stones, yet I am not aware of a single case in the medical literature of kidney stones due to oral intake of vitamin C. This remains only a theoretical possibility because vitamin C increases the amount of oxalate in the urine. According to Linus Pauling there is no need to limit taking vitamin C even with a known predisposition to kidney stones providing the class of stones predisposed to is known. Vitamin C in an acidic form can be taken for those with stones that form in alkaline urine, and vitamin C in alkaline form can be taken for those with stones that form in acid urine.
This mineral has been shown to inhibit the formation of both calcium oxalate and calcium phosphate crystals in the urine. The use of magnesium as a cure for kidney stones has been documented as far back as 1697. In a Swedish study, 200mg of magnesium hydroxide was given daily for 2-4 years to 55 patients who averaged one stone a year. 43 similar patients were used as controls. In the magnesium group only 8 patients reported new stones, whereas 25 reported new stones in the control group. However not all researchers have been convinced by the use of magnesium to prevent stones and this has not become standard treatment.
The kidneys have a large reserve capacity and so evidence of ill health may not be obvious with vague symptoms. Symptoms may be as follows:
rose coloured urine
dripping after urination
difficulty passing urine
rarely need to urinate
frequent bladder infections
painful/burning when passing urine
urination when coughing or sneezing
strong smelling urine
puffiness around eyes/ankles etc.
high or low
uraemia with headaches, dizziness, intractable hiccuping, bad taste in the mouth, bad breath.
in rare cases will be white near the cuticle and dark near the tip.
Dietary factors that may be involved in kidney disease include high protein, high fat diets, lack of water, and drinking too many soft drinks. Animal studies have shown that a 33% reduction in calories markedly decreased the occurrence of diseases of the kidneys. A diet high in essential nutrients and low in calories slows the progressive and deleterious changes in the kidneys with ageing.
Many drugs can cause damage to the kidneys including over the counter medications such as antacids, aspirin and paracetamol. Chlorine and fluoride in the water cannot be handled by some patients as well as other chemicals especially pesticides. Toxic metals can also cause damage to the kidneys. For example nickel is toxic in anything beyond very minute amounts. Cadmium, another toxin that is present in the environment and in cigarette smoke concentrates in the kidney and has been known to cause kidney damage.
The use of raw kidney concentrate which contains growth and repair factors has been used where detoxification is required, in treating high blood pressure, prostate enlargement, bacterial or viral inflammation, nephritis, cystitis, and in fluid and electrolyte imbalances. It has also been used as part of a programme in treating kidney stones. In all cases of kidney dysfunction, the liver (protein metabolism) should also be considered and supported and vice versa. If the liver is below par, the kidneys should be supported. Vitamin A (epithelial factors) should also be considered.
Sources for this article:
Bartlett, P. The Kidneys (Enzyme Digest, May 1992)
Heiby, W. The Reverse Effect (MediScience Publishers, 1987)
Chaitow, L. The Raw Materials of Health (Thorsons, 1989)
Walford, R. The 120 Year Diet (Simon & Schuster, 1986)
Pauling, L. How To Live Longer & Feel Better (Avon, 1987)
Werbach, M. Nutritional Influences on Illness (Thorsons, 1987)
Polen, D. Product Information Notes 1990
Bloomsbury Good Health Guide 1987
This article was first published in Enzyme Digest No. 32 New Year 1997
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