Download - Minerals- CA Mg & P
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D R . C Y R I L J A C O BK U R I A N
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Sources
Milk
Egg, fish, vegetables
Cereals
Daily requirements
Adult : 500mg/dayChildren : 1200mg/day
Pregnancy and lactation : 1500mg/day
Calcium
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Occurs in the first and second part of
duodenum
Absorption requires a carrier protein, helpedby Calcium dependent ATPase
Factors increasing absorption Vitamin D which induces synthesis of the carrier protein
Calbindin in the intestinal epithelial cells Parathyroid hormone increases calcium transport from
intestinal cells
Acidity favors calcium absorption
Amino acids, especially lysine and arginine
Absorption of Calcium
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Factors decreasing Calcium absorption Phytic acid present in cereals
Oxalates present in some leafy vegetables
In malabsorption syndromes causing steatorrhoea, fattyacid is not absorbed, causing formation of insoluble saltsof fatty acid
High phosphate content will cause precipitation ascalcium phosphate
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1. Activation of enzymes
2. Contraction of muscle fibres3. Transmission of nerve impulses
4. Calcium- calmodulin complex regulatesmicrofilament mediated processes such as
degranulation of secretary vesicles,endocytosis, cell motility etc.
Functions of Calcium
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5. Secretion of hormones such as insulin,parathyroid hormone etc. from the
endocrine cells.6. Calcium and cAMP are second messengers
of different hormones. E.g. glucagon
7. Permeability of serum through capillaries isdecreased by calcium
8. Calcium is known as factor IV in bloodcoagulation cascade
Functions of Calcium
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9. In myocardium, calcium prolongs systole
10. Bulk of calcium is used for bone and teethformation
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Normal blood level of calcium is 9-11mg/dl
Blood levels of Calcium
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Factors Regulating Blood Calcium
Levels
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Effects on Vitamin D Parathormone Calcitonin
Blood
Calcium
Increased Much increased Decreased
Intestine Increased Increased (indirectly)
Bone Increasesbone formation Demineralization Opposesdemineralizaton
Kidney Increased calcium
reabsorption and
increased phosphateexcretion
Increased
phosphate
excretion
Deficiency
manifestation
Rickets Tetany
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Other factors affecting serum calcium include Phosphorus
Serum proteins
Acid and alkali
Renal threshold, etc.
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Blood calcium more than 11mg/dlMajor cause is hyperparathyroidism caused
by a parathyroid adenoma or an ectopicparathormone secreting tumor.Clinical signs include osteoporosis, punched
out areas on X-ray, pathological fractures,
polyuria, bilateral recurrent renal calculi,ectopic calcification in arterial walls, muscletissues etc., anorexia, muscle wealness andshort QT interval on ECG.
Hypercalcemia
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Serum calcium
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X-linked dominant condition
Although PTH level is normal, there is
abnormal end organ response to PTH.This leads to hypocalcemia and
hyperphosphatemia
Shortening of 4th and 5th metacarpal and
metatarsal bones may be associated
Pseudohypoparathyroid
ism
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Defective H production in the renal tubules
Kidney cannot lower urinary pH below 5
Excess urinary loss of bicarbonate, sodium,potassium, calcium, magnesium andphosphates. Serum calcium and bicarbonate
levels are lowered.Bone changes are similar to rickets, so often
called Renal Rickets.
Renal Tubular Acidosis+
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Glucosuria and aminoaciduria are associated withhypercalciuria and hyperphosphturia. Consequently,
serum calcium levels are lowered.
Fanconi's Syndrome
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Mainly an intracellular ion
Functions of phosphate ions are:1. Formation of bones and teeth
2. Production of high energy phosphate compounds likeATP,GTP,CTP,creatine phosphate etc.
3. Synthesis of nucleside co-enzymes likesuch as NAD
and NADP4. DNA and RNA synthesis ,where phosphodiester
linkages form the backbone of the structure
Phosphorus
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5. Formation of phosphate esters likeglucose-6-phosphate, phosphoproteins
and phospholipids6. Activation of enzymes
7. Phosphate buffer system in blood
Serum phosphate level is 3-4mg/dl innormal adults and 5-6mg/dl in children
Requirement is 500mg/day
Surces include milk, cereals, nuts and meat
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Mainly an intracellular ion
Requirement
400mg/day Men300mg/day Women
Sources
Cereals, beans, leafy vegetables and fish
Normal serum magnesium level is 1.8 - 2.2mg/dl
Magnesium
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Functions of Magnesium: Activator of enzymes
Lowers neuromuscular irritability Improves glucose tolerance