Title : Information on Calcium
Calcium is actually the most abundant cation within the human Centeng, along that has a very important mineral for the maintenance of neuromuscular function. which constitutes 2% of the total Centeng weight along with 26% of the dry weight of bones along with teeth, as phosphates along with carbonates. About 0.5 g serum calcium is actually exchanged with bone calcium every day.
ABSORPTION
The absorption of calcium depends on the factors listed below.
1. Centeng needs. In a normal person only 30% of calcium is actually absorbed, nevertheless in a deficient person the proportion absorbed is actually higher.
2. Concentration. additional factors being equal, the higher the concentration of calcium within the food, the greater the absorption.
3. Intestinal motility. Intestinal hurry diminishes the absorption of calcium. With chronic diarrhoea along with prolonged use of purgatives, calcium absorption is actually diminished considerably.
4. Fat. When fat absorption is actually deficient, as in steatorrhoea, calcium .combines with fatty acids within the bowel lumen to form
insoluble calcium soaps. Decreased fat absorption also diminishes absorption of vitamin D.
5. Ingested food. Absorption of calcium through food is actually similar whether which is actually taken as whole milk, chocolate milk, yoghurt or
cheese. The absorption is actually also similar whether calcium is actually taken in milk or as calcium acetate, lactate, gluconate, citrate, or carbonate.1 The amino acid L-Iysine helps in positive calcium balance, not only because which enhances calcium absorption, nevertheless also because which improves conservation of absorbed calcium. Lactose (milk sugar) along with amino acids, such as arginine along with tryptophan, enhance calcium absorption. When co-administered with glucose polymer, the absorption of calcium chloride increased 1.5 to 5-fold even in vitamin D-deficient patients.
Cereals contain phytic acid (inositol hexaphosphate), which combines with calcium to form insoluble calcium phytate which is actually not absorbed. Similarly, foods containing oxalate, such as spinach, combine with calcium to form insoluble calcium oxalate. An excess of magnesium apparently diminishes absorption of calcium. Intestinal lactase deficiency leads to decreased milk (along with consequently calcium) intake, along with possible also decreases calcium absorption.
6. Vitamin D. The most important factor in promoting calcium absorption is actually vitamin D, which stimulates the formation of a calcium-binding protein which enhances calcium absorption. When vitamin D is actually not consumed, as that has a strict vegetarian (vegan)
diet (which excludes even milk as which is actually considered to be of animal origin), or if the skin is actually not exposed adequately to sunlight, severe vitamin D deficiency results in poor absorption of calcium.
Vitamin D3 (calcitriol: 1,25 dihydroxy vitamin 03) 400-800 IV may be of value in ensuring calcium absorption. With high doses of vitamin 0, the absorption of calcium through foods can be almost complete, along with which is actually possible to maintain a positive calcium balance even on a low intake.
Glucocorticoids along with alcohol decrease intestinal calcium absorption.
7. Calcium-phosphorus ratio. The ratio of calcium to phosphorus in food has an important influence on absorption. Most foods
containing calcium also have a proper proportion of phosphorus. Milk, eggs, along with some leafy vegetables like lettuce provide these elements within the required proportions.
BLOOD LEVELS
Calcium is actually present in plasma nevertheless not in red blood cells. The serum level is actually about] 0 mg per 100 ml (2.4 mmol / l), about half
of which is actually ionized along with the remainder protein-bound. Ionized calcium is actually diffusible. Its normal serum level is actually maintained by the parathyroid glands. Alkalosis reduces the level of ionizable serum calcium. Diminution of ionic calcium leads to increased muscle irritability along with tetany.
The rest of the serum calcium is actually bound to proteins, mainly albumin, to ensure which when the plasma albumin falls the level of serum
calcium is actually low; nevertheless since This specific decrease is actually only within the non-diffusible form, tetany does not develop.
REGULATING FACTORS
Parathyroid hormone (PTH) mobilizes calcium along with phosphorus through the bones to maintain the blood level.
Hyperparathyroidism causes reabsorption of minerals together. with bone matrix, giving an X-ray appearance of cysts within the
bones (osteitis fibrosa cystica), most apparent within the skull. which may also manifest as kidney stones without detectable bone alterations. PTH also stimulates the mitochondria of the kidney to boost conversion of calcidiol to calcitriol, which enhances
intestinal calcium absorption.
Calcitonin is actually a peptide hormone produced by the C cells of the thyroid gland. Having a very short half-life, which is actually secreted
continuously. The secretion increases with rising serum calcium. which helps to maintain blood level by preventing calcium Discharge through the bones along with increasing urinary excretion.
Therapeutically, calcitonin is actually used when serum calcium is actually high, as in Paget's disease (where which decreases bone reabsorption),
along with in hyperparathyroidism along with breast carcinoma (where which increases urinary calcium excretion). Estrogen raises the level of calcitonin along with prevents bone loss. Postmenopausal bone loss is actually ascribed to decreased estrogen; therefore, calcitonin rather
than estrogen therapy is actually suggested for the prevention of postmenopausal bone loss, as well as for the treatment of
osteoporosis.
STORAGE
Most of the Centeng calcium (99%) is actually stored within the bones along with teeth. The skeleton is actually the dynamic reservoir where calcium is actually continuously deposited along with reabsorbed. This specific dynamic activity is actually high within the young along with declines with age. About one per cent
of total Centeng calcium is actually within the circulation along with soft tissue.
One episode of mild to moderate malnutrition, occurring during the first year of life, is actually associated many years later with
increased caries in both the deciduous along with permanent teeth.
At puberty, under the influence of sex hormones, girls accumulate about 0 mg, along with boys 400 mg, calcium a day. Positive calcium balance occurs only if the calcium intake is actually over 1000 mg a day.
EXCRETION
About half the daily calcium intake is actually excreted within the feces, representing unabsorbed calcium along with calcium through endogenous
sources. If a high dose of vitamin D is actually taken, the calcium content of the stools decreases.
About half the total daily calcium intake is actually excreted through the urine. Urinary excretion of calcium is actually the net result of
glomerular filtration along with tubular reabsorption. The urinary excretion is actually under the control of the parathyroid glands, along with
represents mostly endogenous calcium. The normal range of urinary calcium in adults on a normal diet is actually 100-300 mg (2.5-7.5 mmol) per day for men along with 100-250 mg (2.5-6.5 mmol) per day for women. The kidneys conserve calcium during deficiency.
With normal kidney function, about eight per cent of filtered calcium is actually excreted. With the administration of the diuretics
frusemide or ethacranic acid, resorption of calcium by the kidneys is actually inhibited along with the urinary loss is actually increased to 12%.
Thiazides, on the additional hand, conserve calcium by increasing kidney tubular reabsorption, along with the urinary loss is actually only three
per cent. Therefore, in older patients with high blood pressure-particularly in women-bone loss along with osteoporosis occur with frusemide. Thiazide is actually recommended for prevention as well as treatment of osteoporosis. By decreasing calcium excretion,
thiazide is actually also useful in preventing recurrence of kidney stones.
High-protein diet decreases reabsorption of calcium by the kidneys along with increases urinary calcium excretion.
FUNCTIONS
Calcium along with phosphorus are necessary for bone formation.
Bones consist of a protein matrix (framework) in which calcium phosphate is actually deposited. Proteins, vitamins A along with C, along with sex
hormones are necessary for the formation of the matrix. The calcium within the bones is actually always being turned over with calcium in
the blood along with additional tissues, at a rate of 0.5 g (12.5 mmol) per day.
Ionic calcium affects neuromuscular excitability of both the voluntary along with involuntary muscles. When the ionic serum calcium
concentration. is actually diminished, neuromuscular excitability is actually considerably increased, as in tetany.
Calcium is actually also necessary for clotting of blood along with maintenance of capillary permeability.
SOURCE
Milk along with milk products are the best sources of calcium. Calcium in milk is actually better absorbed than in additional foods, because lysine along with lactose (milk sugar) enhance calcium absorption. Fatty preparations like butter, cream along with ghee are poor in calcium nevertheless contain an adequate amount of vitamin D which aids in calcium absorption.
The daily calcium requirements of a man are easily supplied by a cup of buffalo milk. Molasses along with vegetables, like peas, beans, pulses, potatoes, cauliflowers, along with dried figs, also supply calcium. Pumpkin leaves have a calcium content of 240300 mg (6-7.5 mmol) per 100 g. Chewing betel leaves with lime (calcium hydroxide) augments dietary calcium. Hard water contains calcium, which can be better absorbed in tropical countries with vitamin D derived through exposure to sunlight. Those who chew fish bones are also assured of adequate calcium intake. A solution of bones soaked in vinegar for several weeks, a practice of the Indo-Chinese, is actually a Great source of calcium.
The tropical diet of rice, wheat or millet is actually deficient in calcium, nevertheless Centeng exposure to sunlight produces vitamin D, which
improves absorption along with tends to compensate for the low intake. within the West, the compulsory addition of calcium (fortification) to wheat flour ensures adequate calcium intake.
Calcium carbonate is actually the cheapest commercial source of calcium.
REQUIREMENTS
Humans have a remarkable capacity to adapt to low calcium intake; which is actually compensated for by diminished urinary excretion along with
increased intestinal absorption.
The daily requirement for calcium ingestion varies according to factors favorable or otherwise to its absorption. within the
tropics, with exposure to sunlight, a positive calcium balance is actually maintained even on a calcium intake lower than is actually generally
recommended. The requirement increases with physical activity, along with is actually greater in athletes.
The current calcium intake of American girls during pubertal growth period is actually not adequate, along with increased intake has been
recommended.
Pregnancy increases the demand for, as well as the absorption of, calcium. An infant at birth has more than 20 g (500 mmol) calcium, the major portion of which is actually accumulated within the last three months when the bones of the fetus are formed. Even if extra calcium is actually not taken by the mother, the fetus still derives calcium through the mother's bones. When there is actually marked deficiency of calcium, the mother may suffer through osteomalacia. About 1.2 g (30 mmol) calcium per day is actually adequate for the
mother during the last trimester.
Lactation involves loss of calcium; human milk contains 20-30 mg calcium per 100 ml (5-7.5 mmol / l). If 1000 ml of milk is actually
secreted, 300 mg (7.5 mmol) extra calcium has to be absorbed by the mother. Even 'if the mother's calcium intake is actually not
adequate, the concentration of calcium in her milk is actually maintained at the necessary level by mobilization through her bones. To allow for losses along with daily -needs, a lactating mother requires 1.2 g (30 mmol) calcium daily.
Infants who are breast-fed require 50 mg (1.25 mmol) calcium per kg of Centeng weight daily. Artificially-fed infants require two to three times This specific quantity of calcium, as absorption through artificial sources is actually not as efficient as through mother's milk.
DEFICIENCY (HYPOCALCEMIA)
Low serum calcium levels are seen fn the situations listed below.
1. Hypoparathyroidism along with pseudohypoparathyroidism.
2. Vitamin D deficiency (i) due to poor diet; (Ii) in regions where women do not expose themselves to sunlight; or (iii) due
to diminished absorption in steatorrhea.
3. Low serum proteins (hypoproteinemia), in which the non-diffusible fraction bound to albumin is actually reduced.
4. Kidney disease, in which there is actually retention of phosphate or failure to acidify the urine, leading to systemic acidosis along with
loss of calcium.
5. Acute pancreatitis, where the pancreatic enzyme lipase is actually released into the peritoneum along with blood, splitting fat into
glycerol along with fatty acid, the latter combining with calcium to form soaps.
6. Ingestion of drugs along with toxins like sodium, fluoride along with viomycin.
7. Following hypothermia for cardiac surgery.
8. Following gastric surgery, probably due to deficient vitamin D absorption. These patients respond to daily oral doses of 32.5 micrograms, or weekly injections of 25 micrograms of vitamin D. Some cases of hypocalcemia after gastric surgery may be due to hypoproteinemia.
9. High-protein diet, which increases urinary calcium excretion.
10. Rheumatoid arthritis, where considerable calcium is actually lost early within the disease.
Information on Calcium
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