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1. CALCIUM AND PHOSPHOROUS METABOLISAM
Introduction
- As dentists, it is vital for us to have a complete understanding of the
general metabolism of calcium and phosphorous as it is these minerals
that help in the formation and maintenance of the teeth and their
supporting bony structure.
- 2 points need to be kept in mind during the course of this discussion.
1. Ca++
metabolism is a very complicated and controversial topic on
which no definite conclusion has yet been reached, which is acceptable
by all researchers.
2. This topic deals with factors affecting Ca++
metabolism in the body as a
whole and it should not be assumed that all these factors necessarily
affect the teeth.
1

2. IMPORTANCE AND DISTRIBUTION OF Ca++
IN THE BODY
- The human body contains about 1kg of Ca++
of which 99% is in the
skeleton and remaining 1% in soft tissues and ECF (990gms) and
(10gms).
of 990 gms in the skeleton
- 10 gms forms the readily
exchangeable Ca++
pool of
bone (MISCIBLE POOL)
- 980 gm  slow exchange of
Ca++
takes place (STABLE
POOL)
10.0-10.5mg/dl
NORMAL SERUM
CALCIUMLEVEL
Remaining in soft
tissues
Diffusible/ ultrafilterable form 5.5mg/dl Non-diffusible / protein bound form
4.5mg/dl
Ionized Ca
5.0mg/dl
Bound to PO4,
HCO3, Citrate
0.5mg/dl
Bound to albumin
4.0mg/dl
Bound to
globulin
0.5mg/dl
2
10gms

3. FUNCTIONS OF CALCIUM
1. Contributes to hardness of bone and is a major component of teeth.
2. Stabilises the cell membrane and their permeability.
3. Maintenance of excitability of nerve and muscles.
4. Normal skeletal and cardiac muscle contraction.
5. Helps in the neurotransmitter release.
6. Secretion of granular material from exocrine and endocrine glands.
7. Hormone release and activity – discharge of non-adrenaline in the
nerve terminal cell.
8. Synthesis of nucleic acid and protein.
9. Blood coagulation – Ca++
is required for the conversion of many
inactive enzymes in the coagulation process.
DAILY REQUIREMENTS OF CALCIUM (WHO estimate)
6 months – 2 year = 0.5-0.6 g/day
1200 mg/day
16 years to adults = 0.5-0.6g/day
Pregnancy and lactation = 1.0-2gm/day
Children = 800mg/day
3

4. SOURCES OF CALCIUM AND PHOSPHOROUS
- Milk + milk products.
- Egg.
- Meat
- Fish
- Leafy vegetables
- Hard water
PHOSPHOROUS
DISTRIBUTION OF PHOSPHOROUS IN THE BODY
- The human body contains 500-600 gms of PO4
--
out of which 85%
(425g) is in the bone.
- Remaining phosphorous is present in the liver, pancreas and brain.
- Phosphorous is essential for the formation of teeth. Normal serum PO4
--
level is 2.5 – 4.5 mg/dl.
Serum inorganic form Organic phosphorous
3-4 mg/dl in adults remaining in the form of
phospholipids & glycerophosphates
5-6mg/dl in children
4

5. FUNCTIONS OF PHOSPHOROUS
1. Formation of bone and teeth. It is the essential constituent of all
cells.
2. Important constituent of high energy phosphate compounds like
ATP, creatine phosphate, cyclic AMP, hexose phosphate, 2-
3DPG, phospholipids, nucleotides.
3. Helps in the regulation of glycolysis.
4. Phosphorylation of lipids and sugar i.e. absorption,
transportation and metabolism.
5. Urinary buffer, which regulates urinary pH.
DAILY REQUIREMENTS OF PHOSPHOROUS – 1gm/day
CONCEPT OF CALCIUM BALANCE
This term is used to describe the amount of Ca++
either stored or lost by
the body over a specific period of time. This can be calculated by deducting
the amount of Ca in the urine from the Ca taken in the diet.
Ca in diet - Ca in fasces  Ca absorbed – Ca in urine
Ca lost / gained
5

6. e.g., If 1.0gm Ca is in the diet – 0.7 gm in fasces  0.3g absorbed. 0.1g net
gain  0.2g in urine
The Ca balance values are said to change with age.
 In a growing child, there is a Net gain for growing and mineralizing
skeleton.
In an aging adult, there is a Net loss as Ca from bone is lost too due to
conditions like osteoporosis. Hence, amount of Ca lost is greater than Ca in
intake.
ABSORPTION OF CALCIUM AND PHOSPHOROUS
It is seen that almost all the food taken in three the diet is almost completely
absorbed in the gut whreas the amount of minerals absorbed is very negligible.
 This could be due to the various factors affecting the absorption of Ca++
and PO4
--
.
 The factors can be studied under:
Factors affecting mucosal cell Factors influencing Ca absorption in the gut
FACTORS INFLUENCING MUCOSAL CELLS
1. Vitamin D and Ca absorption
6

7. It is seen and proven that the active form of vitamin D or 1,25 DH CC
(di-hydroxy cholecalciferol) increases the absorption of Ca in the gut, kidney
and bone.
This increase in absorption of Ca is directly related to the increased
concentration of Ca binding protein produced by increasing synthesis of
mRNA.
1,25 DHCC
↓
Increases synthesis of mRNA
↓
Increases level of Ca binding protein CBP
↓
Increases Ca plasma level
2. Effect of dietary Ca intake and Ca need
 It is seen by means of experiments that the amount of Ca STORED in the
body is a factor which influences Ca absorption.
This factor can be better understood with the help of an example. e.g.,
Rottenson in 1938 used 2 groups of rats for his experiment
He fed 1st
group 2nd
group
0.15% Ca for 4 weeks 0.8% Ca for 4 weeks
4 weeks later he observed that
7

8. Stored - 190mg Ca was stored (↓) (↑↑) 570mg Ca was stored
Thus suggesting that greater the dietary intake of Ca, greater amount of
Ca is stored.
In the 2nd
stage of experiment, both groups received 0.4% Ca for 5 weeks.
0.4% Ca 0.4% CA
5 weeks 5 weeks
5 weeks later ABSORBED AMOUNT
900 mg (↑↑) 600 mg (↓)
This suggested that the group with a low Ca store absorbed more Ca
than the group with the high Ca store. Thus, suggesting that the amount of Ca
absorbed is directly dependent on the amount of Ca present in the store. This
kind of an adaptation mechanism is directly under the control of formation of
1,25 DHCC.
3. Effect of pregnancy and growth
- During pregnancy, the amount of dietary Ca absorbed increases
especially in the later months of pregnancy. Half of the Ca
absorbed during pregnancy goes to the developing foetus and the
remaining half is stored in the mother’s skeleton as a reserve for
lactation.
8

9. - 2 hormones are active during pregnancy
9

10. PLACENTAL LACTOGEN OESTROGEN
Increases Ca absorption Acts by increasing release of PTH
which increases Ca absorption
indirectly.
Hence, in later stages of pregnancy
increased PTH levels are reported.
Growth Period
- During growth of children, the growth hormone levels are high.
This acts by increasing Ca absorption and reducing amount of
endogenous Ca excretion.
Parathyroid hormone
- Is one of the main hormones controlling Ca absorption. It mainly
acts by controlling the formation of 1,25 DHCC which it active
form of vit. D which is responsible for increased Ca absorption.
CALCIUM : PHOSPHOROUS RATIO  An increase in the plasma Ca
level causes a corresponding ↓ in absorption of phosphorous and vice-versa.
The product of Ca and inorganic phosphate of the blood is always constant
(ratio is 2 Ca : 1 PO4).
10

11. II  FACTORS INFLUENCING AVAILABILITY OF CALCIUM IN
THE GUT
1. pH of the intestine
• It is seen that the acids of the gastric juices dissolve
most of the Ca salts and inorganic phosphate in the diet hence allowing
greater amount of Ca available for absorption.
• In the lower part of the small intestine, the pH is said
to be more alkaline, thus causing Ca salts to undergo precipitation. Hence
Ca absorption occurs only in the upper part of the small intestine where the
pH is acidic.
In patients wth achlorhydria/gastrectomy, less Ca absorption takes
place.
2. Amount of dietary Ca and PO4
As discussed before, as the levels of dietary Ca and PO4 is
increased, the amount of Ca and PO4 absorbed also increases but only
upto certain limit beyond which no more absorption takes place.
This is because the active transport system in the mucosal cells can
deal with only a certain load of Ca. Once this load is exceeded, the
11

12. remaining Ca is either excreted or passively diffuses in the lower part
of the gut.
This a homoestatic mechanism for preventing excessive
concentration of Ca in the blood or tissue which could have a
hazardous effect.
3. Phytic acid and phytates
Are found in foods like – Oat meal
Whole wheat
Cereals
They are considered to be anti-calcifying factors as they combine with
the Ca of the diet thereby forming insoluble salts of Ca which are not
absorbable. Hence, if these phytates are taken in a diet, where the Ca intake is
low or vit. D intake is low, it is seen that severity of the deficiency disease
worsens.
The effect of phytates is said to be quantitative and can be neutralized
by adding sufficient extra Ca to the diet.
4. Effect of Oxalates
Oxalates is another substance present in certain foods like spinach and
rhubarb leaves. These oxalates precipitate significant amounts of Ca from the
12

13. diet or from the digestive juices thereby decreasing the amount of Ca available
for absorption.
Hence, it may be noticed that after eating spinach, a certain roughness
can be experienced on the surface of the teeth which is due to the precipitation
and deposition of Ca oxalate crystals (Ca from the saliva) on the teeth.
5. Effect of fat
Fat combines with Ca forming insoluble Ca soaps which decreases Ca
absorption but increases the availability of phosphorous for absorption.
Fat combines with Ca and liberates PO4 for absorption. Hence, excess
fats hinder Ca absorption but favour phosphorous absorption.
6. Effects of proteins and Aminoacids
It is seen that a considerable increase in the Ca absorption occurs with a
high protein diet.
13

14. Proteins and Amino acids effect Ca in 2 ways:
Proteins form soluble complexes thus
allowing Ca to remain in a form
which is easily absorbable
Protein metabolism leads to formation
of certain acids that encourages the
removal of Ca from the skeleton.
Hence, urinary Ca level increase with
a richer protein diet
Hence a high protein diet may be
considered as a possible factor for
osteoporosis.
But under such conditions, the
increased absorption is of no value as
this absorbed phosphorous cannot be
retained without Ca. Hence the excess
phosphorous is quickly excreted.
7. Effect of carbohydrates
It is seen that certain carbohydrates like lactose create an acidic pH in
the gut by favouring growth of acid producing organisms. This acidic
environment of gut favours Ca absorption.
14

15.  Contradictory studies show that an increased level of Ca is seen in the body
not by increase in Ca absorbed but by decrease in Ca excreted in urine.
8. Bile salts favours Ca and phosphorous absorption as it dissolves fats
thereby allowing greater amounts of Ca+ phosphorous to be available
for absorption.
HORMONAL CONTROL OF CALCIUM METABOLISM
 A complex set of interlocking mechanisms takes place in order to allow
man to survive major dietary Ca intake fluctuations. These mechanisms are
mainly controlled by the endocrine systems.
Three main hormones acting at 3 different sites are responsible for Ca
metabolism.
1. Vit. D3 Bone.
2. Parathormone Kidney
3. Calcitonin Intestine
1) Vit. D3 is a steroid derivative
Vit. D3 – cutaneous synthesis – important in Ca metabolism.
Vit. D2 – Ergocalciferol
Dietary source is fish, milk and eggs.
• Vit. D is also known as cholecalciferol.
15

16. • Besides dietary intake, cutaneous synthesis of vit.D. is
another important source of Vit. D in the body.
• Present within the inner layers of the epidermis, lies
an enzyme known as 7-dehydrocholesterol. UV Rays PRE VITAMIN
D3
Bound Binding protein (DBP)
to Vit. D and taken to liver
IN LIVER
Taken to kidney
Pre Vit. D3 IN LIVER 25, OH cholecalciferol (main circulating subs, but
it is relatively inactive as it is bound to α globulin.
25-OH-CC
Undergoes
Hydroxylation by
1-α-hydroxylase enzyme whose
formation is under the control of
PTH
1,25,
Dihydroxycholecalciferol
or calcitriol (active form
of Vit. D3 which is
considered to be a
horomone)
- Daily requirements of vit. D  400 I.U.
Action of Vit. D.
Vit. D. acts on the intestine, kidney and bone thereby bringing about an
increase in the Ca absorbed. The active form of vit. D which is produced in the
16

17. kidney has its action on many tissues away from the site of its production.
Hence 1,25DHCC is often known as a hormone.
Acts mainly by increasing the synthesis of mRNA which directly
increases the concentration of (CBP) Ca binding protein mainly in the tissues
of the intestinal mucosa. The CBP thereby binds with increased amount of Ca
and allows increased Ca to be absorbed.
1. Action on the intestinal
1,25 DHCC increases the synthesis of CBP in the intestinal epithelium
thereby increasing the transportation of Ca from the intestinal lumen to the
epithelium.
Hence, the amount of Ca absorbed is directly proportional to the
amount of CBP present in the mucosal cells.
2. Action the kidney
1,25 DHCC increases the amount of Ca absorbed from the renal
tubules.
3. Action on the bone
Before studying the action of vit. D on the bone we must
understand the term Osteocytic Membrane System.
17

18. As we all know, the cells of the bone are the:
Osteocytes
Osteoblasts
Osteoclasts
The osteocytes / resting bone cells are present within the bone.
The osteoblasts / bone forming cells are found in the endosteum
lining the bone.
The osteocytes and the osteoclasts communicate with each other via
the long cytoplasmic processes. Hence, the osteoblasts present outside
the bone and osteocytes present within the bone form a system of
interconnected cells that spread all over the bone suface.
This extensive system is known as osteocytic membrane system
(OCM).
This system separates the bone from the E.C.F. Bone fluid is
present between bone and OCM).
18

19. Action
Vit. D. / 1,25 DHCC is said to mediate the pump that actively
transports Ca from within the OCM to the ECF thereby raising plasma Ca
levels.
Deficiency of vit. D in the body either due to a deficient diet or due to
insufficient solar exposure results in disorders known as Rickets in younger
children or Osteomalacia in adults.
Rickets - Delayed eruption
- Malallignment of teeth
REGULATION OR CONTROL OF SYNTHESIS OF 1,25 DHCC OR
FEED BACK MECHANISM
The synthesis of active vit. D3 or 1,25DHCC is said to be tightly and
directly regulated by the parathyroid hormone. Hence, an increase in the
dietary Ca results in increased levels of 25 (OH) CC viz., the inactive form.
Any fall in the plasma Ca levels cause release of PTH. This PTH activates
enzyme 1- α - hydroxylase which then converts vit. D3 to active 1,25 DHCC.
19

20. Increases synthesis of CBP hence, there is an increase in Ca absorbed.
During pregnancy, hormones like placental lactogen and oestrogen also have
an effect on 1- α -hydroxylase
2) PARATHYROID HORMONE (PTH)
PTH is secreted by the parathyroid glands which acts located on the
posterior surface of the thyroid gland. They are 4 in number.
PTH acts mainly on 2 sites i.e. a) bone
b) kidney
It acts by a cAMP mechanism to increase Ca levels and decrease in
organic phosphate levels in the plasma.
a) Action on the bone Fast phase
Slow phase
i) Fast phase
Within few minutes of injection of a large dose of PTH, the plasma
Ca levels is said to increase.
Mechanism
PTH mainly acts by increasing the permeability of osteocytic
membrane system to Ca so that Ca from the bone fluid diffuses into the
20

21. osteocytes and osteoblasts from where vit. D mediated active transport
transfers the Ca from within the OMS to the ECF thereby increasing the
plasma Ca levels.
Any decrease in the concentration of Ca within the bone fluid leads to
dissolution of Ca salts from the nearby bones without affecting the bone
matrix (indirectly activates osteoclastic activity or bone resorption).
ii) Slow phase
Several days of increased PTH activity is required to demonstrate
the slow phase.
PTH acts by
Activating the bone resorbing cells /
osteoclasts
Forming new osteoclasts from the
osteoprogenitor cells
Osteoclasts are multinucleated giant cells which produces resorption of
bone surfaces in contact with them. The osteoclasts send out long finger-like-
21

22. projections towards the bone. These finger like projections release a.
PROTEOLYTIC ENZYMES which digests the organic matrix.
b. ACIDS like citric / lactic acid which dissolves the bone
minerals.
The Ca and PO4 released are poured into the ECF.
b) Action on kidney (↑↑Ca++
)
- Increases the resorption of Ca from the distal tubules (↓↓ PO4
– –
).
- Decreases the resorption of PO4 from PCT thereby causing
phosphaturia and hypophosphatameia.
- Increases the synthesis of 1-α-hydroxylase which is responsible for the
active form of Vit. D which increases Ca absorption.
REGULATION OF PTH SECRETION
The plasma Ca levels are said to have a direct influence on the PTH
secretion.
Any fall in the Ca levels causes a release of the PTH which brings back
the level to normal. Similarly increase in plasma Ca level inhibits the secretion
of PTH.
22

23. 3.CALCITONIN
Is secreted by the parafollicular cells by the thyroid glands. Mainly acts
to maintain the integrity of the bone.
Actions
It mainly acts by decreasing the permeability of OMS to Ca thereby
increasing the amount of Ca deposited in the readily EXCHANGEABLE
CALCIUM POOL OF BONE.
It prevents the formation of new osteoclasts from osteoprogenitor cells
thereby preventing bony resorption.
REGULATION OF SECRETION OF CALCITONIN
The release of calcitonin is regulated by the plasma calcium levels. A
rise in the plasma Ca level above 9mg% stimulates the release of calcitonin.
Hence, plasma Ca levels controls the direction of PTH and calcitonin.
In adults, role of calcitonin is very minor and normal Ca level is
maintained chiefly by PTH.
Calcitonin plays a major role in pregnancy. It protects the bones of the
mother from excessive loss of Ca as during pregnancy PTH and 1,25DHCC
levels are high.
23

24. EXCRETION OF CALCIUM AND PHOSPHOROUS
Ca is said to be excreted both in the faeces and in the urine. About 90%
of the total amount of Ca is excreted in the faeces.
Ca of the urine is excreted as calcium chloride (CaCl2) and (CaPO4) 
10% remaining.
The approximate daily turnover rates of Ca in an adult are as follows:
Intake 1000mg
Intestinal absorption 350mg
Secretion in GIT juice 250mg
Net absorption over secretion 100mg
Loss in the faeces 100mg
Excretion in the urine 100mg
BUFFER ACTION OF PHOSPHOROUS IN BLOOD
2 varieties of phosphates are present in the blood
Alkaline Acidic
H2PO4 HPO4
Concentration is about Concentration is about
1.05m mol/lit 0.26 m mol/lit
24

25. In the plasma they are in a ratio of alkaline 4 : 1 acidic.
Where pH of extra-cellular fluid becomes more acidic there is a relative
increase in H2PO4
–
and HPO4
– –
and the opposite happen when fluid is alkaline.
The average total quantity of inorganic phosphorous ranges between normal
limits of 3-4mg/dl in adults and 4-5mg/dl in children.
IMPAIREMENTS IN BLOOD CALCIUM
I] Hypercalcemia
Increased level of Ca in the blood.
Symptoms
- Tiredeness
- Loss of appetite.
- Nausea, vomitting.
- Constipation.
- Polyuria.
- Dehydration.
- Loss of muscle tone.
- Decreased excitability of muscles and nerves.
Conditions in which it occurs
- Hyperparathyroidism.
25

26. - Acute osteoporosis.
- Vit. D intoxication.
- Thyrotoxicosis.
II] Pathologic calcifications of soft tissues
3 theories have been forwarded for the mechanism of calcification
a) Nucleation theory
Ca is deposited both inside and outside the cells (in mitochondria)
which later coalesce together to form calcified tissues.
This proposes that organic matrix components facilitate precipitation
by acting as heterogenous nucleating agents like collagen, phospholipids
which act on specific phosphorylating sites.
b) Booster theory
This theory proposes the existence of a mechanism to boost the local
Ca and PO4 ion product to a point where precipitation occurs.
c) Matrix vesicles
Small round vesicular extracellular matrix vesicles about 100nm in
diameter are involved in the initiation of calcification. They are probably
arrived from cell processes originating from the plasma membrane.
26

27. i) Dystrophic calcification
- Precipitation of Ca in degenerating and dead tissues occur.
- Common sites are - Blood vessels
- Kidneys
ii) Metastatic calcification
- Due to excess Ca in the circulating blood, they are deposited in
previously undamaged tissue
- Usually occurs in – Hyper vitaminosis D
Hyperparathyroidism
Destructive lesions of the bones.
- Common sites are - Blood vessels
- Kidney
iii) Calcinosis
- Is calcification occurring in / under skin and can be associated with
scleroderma.
III] Hypocalcemia
- Decreased levels of Ca in the blood (below 4mg is lethal).
Symptoms
- Tetany (Carpopedal spasm).
27

28. a) Chvotek’s sign
- Contraction of ipsilateral facial muscles elicited by tapping over the
facial nerve at the angle of the jaw.
b) Trosseau sign
- Spasms of the muscles of the upper extremity that causes flexion of
wrists and thumb and extension of fingers.
- This is elicited by occluding the circulation of fingers for a few
minutes.
c) Erbs sign
- Is hyperexcitability of muscles to electrical stimulation.
- This occurs in cases of – - Insufficient Ca in the diet.
- Hypoparathyroidism.
- Insufficient vit. D in the diet.
- Increase in calcitonin levels.
28

29. IV] VIT D. DEFICIENCY
 ↓↓ Ca++
level
Rickets Osteomalacia
- In children.
- Mainly affected the long bones
in the body, ribs.
- Occurs due to failure in
mineralization, due to lack of Ca
level, the cartilaginous form of
bone is said to persist.
- In adults.
- Mainly affects the flat bones in
the body.
- Especially seen in post and
menopausal women who have a
decreased dietary Ca intake and
decreased exposure to the sun
resulting in increased removal of
Ca from the bone causing
softening of the skeleton and its
distortion.
- The cartilage continuous to
grow and proliferate thus resulting
in localized areas of cartilage
proliferation (rickety rosary,
beaded bone formation)
- The weight of the body on the
uncalcified long bones result in the
bowing of legs – knock kness.
-
29

30. Dental
- Development of abnormality in
enamel and dentin.
- Delayed eruption of teeth.
- Mal-alignment of teeth.
- Higher caries index.
- Wider predentine zone.
- Increased amount of inter-
globular dentin.
Dental Findings
- Severe periodontitis
Treatment: Treatment:
Supply adequate amount of Ca and
phosphate in diet and administration
of large amounts of Vit. D.
V] PARATHYROID HORMONE
a) Hyperparathyroidism
- Increases levels of PTH due to an adenoma of the parathyroid glands.
C/F:
- Pathologic fracture of bones due to increased mobilization of Ca from
bone resulting in osteitis fibrosa cystica.
- Large punched out cystic area of bone.
30

31. o Joint stiffness.
o Urinary tract stones.
o Muscle weakness.
o Thirst.
o Polyuria
o Anorexia.
o Weight loss.
Dental findings
- Malocclusion seen due to definite drifting of teeth causing spacing (this
occurs as a result of increased loss of Ca from the bone, there is an
absolute attempt to new bone formation and repair resulting in
spacing).
Radiographically
- Areas of radiolucency seen in bone.
- Loss of lamina dura present.
Treatment
- Removal of cause.
31

32. b) Hypoparathyroidism
- Seen to develop due to excision of the parathyroid glands.
- This is characterized by a fall in the serum Ca levels and an increase in
the serum inorganic phosphate levels.
C/F:
- Similar to hypocalcemia.
- Tingling and numbness in the fingers, face and toes.
- Extreme cases – cramps in the hands and feel which is very painful.
- Carpopedal spasm.
- Spasm of muscles of respiration resulting in the dread of suffocation.
- Signs of tetany present.
- In infants, symptoms of tetany may be confused for epilepsy, though
there is no loss of consciousness.
Dental Findings
- Aplasia / hypoplasia of teeth seen when hypoparathyroidism develops
before teeth formation.
c) Parathyroid poisoining
32

33. - In rare cases, the PO4 level of body fluids rise rapidly when the kidneys
cannot excrete rapidly. Ca and PO4 get supersaturated and lead to
metastatic deposition in lungs, alveoli, kidneys, thyroid gland, gastric
mucosa etc.
- Elevation of blood Ca levels before 17 mg/dl along with concurrent
elevation of PO4
– –
death can occur in few days.
Osteoporosis
- In adults (old age) due to decreased bone matrix rather than poor bone
calcification.
33

34. Summary
Ca and PO4 are important minerals that are required in minimal
amounts for basic activities in the body like the normal ionic Ca levels in the
plasma is required for proper bone mineralization and maintenance of cell
membrane integrity. The plasma Ca levels need to be regulated within a very
narrow range because of its marked effect on neuromuscular and cardiac
excitability.
Three hormones which are – PTH
- Calcitonin
- Vit. D
Play important role in maintaining Ca and PO4 levels to a normal.
34

35. CALCIUM AND PHOSPHOROUS METABOLISM
CONTENTS
Calcium Phosphorous
Introduction
Distribution of Ca in the body
Functions of Ca
Daily requirements
Sources
Absorption of Ca+ PO4
Concept of Ca balance
Factors controlling the absorption of
Ca+ PO4
Hormonal control of Ca metabolism
Vit. D3
PTH
Calcitonin
Excretion of Ca+ PO4
Summary
Distribution of PO4 in the
body
Function of PO4
Daily requirements
Sources
35