This document discusses calcium and phosphate metabolism and related disorders. It covers the distribution, functions, absorption and excretion of calcium and phosphate. It describes the roles of parathyroid hormone, vitamin D, and calcitonin in regulating calcium and phosphate levels. Disorders resulting from calcium and phosphate imbalance like hypercalcemia, hypocalcemia, rickets, and osteomalacia/osteoporosis are explained. Factors affecting calcium and phosphate levels and their clinical importance are also summarized.

1. CALCIUM & PHOSPHATE
METABOLISM
HYPOCALCAEMIA,
HYPERCALCAEMIA
Dr. Tasnim Ara Jhilky
MD- Biochemistry
Phase-A Student.
Sir Salimullah medical college.

2. INTRODUCTION
The minerals in foods do not
contribute directly to energy needs
but are important as body regulators
and as essential constituents in many
vital substances within the body.

3. Principal Minerals include - Calcium,
Phosphorous,
Magnesium, Sodium, Potassium and
Sulphur.
Calcium and phosphorous individually have
their own functions and together they are
required for the formation of hydroxyapatite
and physical strength of the skeletal tissue.

4. DISTRIBUTIONDISTRIBUTION
• Bones and teeth -
99%
• Muscle – 0.3%
• Other tissues –
0.7%
CALCIUM PHOSPAHAT
E
Bones and teeth with
ca. – 80%
Muscle ,blood– 10%
Various che.compound-
10%

5. CALCIUM PHOSPHATE RATIOCALCIUM PHOSPHATE RATIO
Calcium : Phosphate ratio normally
is1:1.
Calcium and phosphate are distributed
in the majority of natural foods in this
ratio .so,adequate intake of ca generally
takes care of phos.requirement also.

6. PLASMA CALCIUM LEVELPLASMA CALCIUM LEVEL
 total plasma calcium con. 9-11 mg/dl.
Or 2.4mmol/l
 Free/ionized calcium ,about ½ of
this,5mg/dl,functionally most active.

7. Forms of plasma calciumForms of plasma calcium
Free/ionized calcium-50%
Protein bound calcium-45%
Calcium complex with citrate
,phosphate-5%

8. Serum Phosphate levels
Children - 4 to 7 mg/dL
Adults - 3 to 4.5
mg/dL

9. Daily Requirements Ca ,PhosphateDaily Requirements Ca ,Phosphate
 Adults 800mg
 Pregnancy 1500mg/d
 Lactating mother 2ooomg/d
 Infants 360mg/d
 Children 800-1200mg/d

10. Dietary SourcesDietary Sources
 Calcium:
- milk and milk
products
- eggs
- fish
- vegetables
- fruits (oranges)
- fortified bread
- nuts
- hard water
 Phosphates:
- same as calcium
- present in high
amount
in cereals and pulses
- absent in hard water

11. Functions of CalciumFunctions of Calcium
 Formation of bone and teeth
 Muscle contraction
 Coagulation of blood
 Nerve transmission:Integrity of
cell membrane by
maintaining the resting
membrane potential of the cells
 Release of certain hormones

12. Major structural element in the vertebrate
skeleton (bones and teeth) in the form of
calcium phosphate (Ca10(PO4)6(OH)2
known as hydroxyapatatite
Key component in the maintenance of
the cell structure
Membrane rigidity, permeability and
viscosity are partly dependent on local
calcium concentrations
Release of hormone
As intracellular messenger

13. Functions of PhosphatesFunctions of Phosphates
Formation of bones,teeth
Formation and utilization of energy rich bonds
in ATP.
Important constituent of cells-
phospholipid,phosphoproteins
• Forms co-enzymes,NAD,ADP,NADP
Regulates blood and urinary pH.
Forms organic molecules like DNA &
RNA
Acts as buffer,facilitate urinary acid excretion

14. Absorption of CalciumAbsorption of Calcium
Calcium is taken through dietary sources as
calcium phosphate, carbonate, tartarate and
oxalate.
It is absorbed from the gastrointestinal tract
(duodenum) in to blood and distributed to
various parts of the body.
Two mechanisms have been proposed for the
absorption of calcium by gut mucosa:
 Simple Diffusion.
An active transport process, involving energy
and calcium pump.

15. FACTORS PROMOTING CAFACTORS PROMOTING CA
ABSORPTIONABSORPTION
Vita D
Parathy.hormone
Low ph
Lactose
FACTORS INHIBIT ABSORPTION
Phytate and oxalate
High dietary phosphate
FFA
Alkaline condition

16. While passing through the kidney, large quantity of
calcium is filtered in the glomerulus. From the
filtrate, 98 to 99% of calcium is reabsorbed in the
renal tubules in to blood and only small quantity is
excreted through urine. In the bone, the calcium
may be deposited or resorbed depending upon the
level of calcium in the plasma

17. Calcium BalanceCalcium Balance
Defined as the net gain or loss of calcium by
the body over a specified period of time.
Calculated by deducting calcium in faeces
and urine from the calcium taken in diet.
Positive calcium balance in growing children.
Negative calcium balance in aging adults.

18. Hormonal Control of Calcium &Hormonal Control of Calcium &
Phosphate metabolismPhosphate metabolism
Three hormones regulate calcium and
phosphate metabolism.
Vitamin D
PTH
Calcitonin

19. VITAMIN-D
Calcitriol (1,25-DHCC) is the biologically
active form of vit-d.
It regulates plasma levels of Ca and P.
Calcitrial acts at 3 different levels
intestine,kidney, bones.
Action on Intestines:
It increases the intestinal absorption of
ca&p in the intestine,by inducing syn.of a
specific ca binding protein in ines.cell.

20. Action on bone:
calcitriol stimulates ca uptake by
osteoblast of bone and promotes
calcification or mineralization(deposition
as capo4) and remodelling .
Action on kidney:
It is involved in minimizing the excretion
of ca&p through kidney by decreasing
their excretion and enhancing
reabsorption .

21. • Parathyroid hormone is one of the main
hormones controlling Ca+2
absorption.
• It mainly acts by controlling the formation of
1,25 DHCC, which is active form of Vit. D,
which is responsible for, increased Ca+2
absorption.
Parathyroid Hormone:

22. Stimulation for PTH secretionStimulation for PTH secretion
 The stimulatory effect for PTH secretion
is low level of calcium in plasma.
 Maximum secretion occurs when plasma
calcium level falls below 7mg/dl.
 When plasma calcium level increases to
11mg/dl there is decreased secretion of
PTH

23. ActionsActions of PTHof PTH
The main function is to increase the
level of Ca in plasma within the critical
range of 9 to11 mg.
 ON KIDNEY
 Parathormone inhibits renal phosphate
reabsorption in the proximal tubule
and therefore increases phosphate
excretion.
 Parathormone increases renal Calcium
reabsorption in the distal tubule, which
also increases the serum calcium.
 Net effect of PTH  serum↑

24. Action on boneAction on bone
Demineralization of bone,carried by
osteoclast…increase blood ca.it very
important for ca homeostasis.it is
noted that,dietary ca deficiency
….means loss of ca from bone.
ACTION ON INTESTINE
Increase intestional absorption of ca
by promoting synthsis of calcitriol

25. CALCITONINCALCITONIN
 Minor regulator of calcium & phosphate
metabolism
 Secreted by parafollicular cells or C-
cells of thyroid gland.
 Also called as thyrocalcitonin.

26. Action of CalcitoninAction of Calcitonin
Calcitonin is a Physiological Antagonist to
PTH with respect to Calcium.
Effect on calcium-decrease ca level,by
increasing activity of osteoblast,decrease
bone resorption and increase excretion in
urine
With respect to Phosphate it has the same
effect as PTH i.e. ↓ Plasma Phosphate level

29. OTHER HORMONES on CALCIUMOTHER HORMONES on CALCIUM
METABOLISMMETABOLISM
GROWTH HORMONE
 INSULIN
 TESTOSTERONE & OTHER HORMONES
LACTOGEN & PROLACTIN
STEROIDS
THYROID HORMONES

30. Increases the intestinal absorption of calcium and
increases its excretion from urine
Stimulates production of insulin like growth factor
in bone which stimulates protein synthesis in bone
Stimulates stomatomedian C which acts on
cartilage to increase the length of bones
GROWTH HORMONE

31. TESTOSTERONE
Testosterone causes differential growth of
cartilage resulting to differential bone
development
Acts on cartilage & increase the bone
INSULIN
• It is an anabolic hormone which favors
bone formation

32. Thyroid HormoneThyroid Hormone
In infants  stimulation of bone growth
In adults
increased bone metabolism  increased
calcium mobilization

33. GlucocorticoidsGlucocorticoids
Anti vitamin D action, decrease
absorption of calcium in intestine
Inhibit protein synthesis and so
decrease bone formation
Inhibit new osteoclast formation &
decrease the activity of old osteoclasts.

34. DISEASE STATEDISEASE STATE
The blood ca level is maintained
predominately byPTH.
so disease mainly due to alterations
in PTH

35. SYMPTOMS OF CALCIUMSYMPTOMS OF CALCIUM
IMBALANCEIMBALANCE
Increased serum Ca
Hyperparathyroidism
.
 Hypervitaminosis
(Vit. D).
 Multiple myeloma.
 Sarcoidosis.
Thyrotoxicosis.
Decreased serum Ca
 Renal failure.
Hypoparathyroidis
m
 Vit. D deficiency.
Tetany.
Malabsorption sy

36. Clinical ImportanceClinical Importance
 Hypercalcemia
Adjusted total calcium level > 10.2 mg/dl
 Consequence of hypercalcemia
 Neuromuscular depression
 Soft tissue calcification
 Cardiac arrhythmia
 Hypercalcemic nephropathy

37. Symptoms:
Polyuria,
dehydration,
confusion,
depression,
fatigue,
nausea/vomiting,
anorexia,
abdominal pain, and
renal calculi
Signs:
Diminished reflexes,
short QT interval on
ECG.

38. Hypocalcaemia
Adjusted total calcium in the blood <8.4
mg/dl
Conditions leading to hypocalcaemia
Insufficient dietary calcium
Hypoparathyroidism
Insufficient vitamin D
↑ in calcitonin levels

39. Symptoms:
Irritability,
muscle cramps,
depression,
bronchospasm, and seizures.
Signs:
Increased reflexes, prolonged QT interval on
ECG (the only cause of a prolonged QT with a
normal duration of the T wave itself)

40. Tetany (Carpopedal spasm)
Neuromuscular hyperexcitablitythat occurs
following hypocalcemia
Basic feature of tetany is uncontrolled,
painful, prolonged contraction (spasm)
of the voluntary muscle.

41. RicketsRickets
Defective calcification of bone
Cause..
low level of vitD or
 due to dietary deficiency of ca, po4
Increase alkaline phosphatase is
characteristic feature

42. Con…Con…
◦ Occurs in children between 6 months to
2 years of age.
◦ Affects long bones
◦ Lack of calcium causes failure of
mineralization resulting into formation
of cartilagenous form of bone.
◦ Most critical area that gets affected is
the center endochondral ossification at
the epiphyseal plates.

43. OSTEOMALACIAOSTEOMALACIA
Osteomalacia is softening of the
bones, caused by not having enough
vitamin D, or by problems with the
metabolism (breakdown and use) of
this vitamin. These softer bones
have a normal amount of collagen
that gives the bones its structure,
but they are lacking in calcium

44. OSTEOPOROSISOSTEOPOROSIS
It is the most common of all bone diseases in
adults ,
especially in old age.
It is different from osteomalacia and rickets
because
it results from diminished organic bone
matrix rather than from poor bone
calcification.
 Characterised by low bone mass,
microarchitectural

45. Con….Con….
ETIOLOGY
Unknown
Decrease production of vit D with
age
Deficiency of sex hormone
TREATMENT
Ca supplementation
Estrogen administration
Higher dietary intake of ca.

46. • Increased intake Diet containing Vit-D
• Increased release of P from cells (DM,
Acidaemia, Starvation)
• Increased release of P from bone (malignancy,
Renal failure, Increased PTH)
• Decreased excretion (Renal failure,
Hyperparathyroidism, Increased growth

47. • Decreased Intake (Starvation, Malabsorption, Vomiting
• Increased cell uptake (High dietary carbohydrate, Liver
disease)
• Increased Excretion (Diuretics, Hypomagnesaemia,
Increased PTH)

48. • It has often been supposed that a low
intake of calcium, or phosphorous, or both
might lead to poor calcification of teeth and
possibly, therefore, to an increased risk of
dental caries.
• the calcification of the teeth could be
affected if calcium was very low in the diet.

49. Pregnancy and growth:
• During later stages of pregnancy, greater
amount of calcium absorption is seen.
• 50% of this calcium is used for the
development of fetal skeleton and the rest is
stored in the bones to act as a reserve for
lactation.
• This is due to the increased level of placental
lactogen and estrogen which stimulates
increased hydroxylation of vitamin D.
.

50. Adjusted plasma total calciumAdjusted plasma total calcium
Adjusted total ca (mmol/l)=
measured total ca(mmol/l)+0.02{47-
albumin (g/l)}
Hypercalcemia=high adjusted ca
Hypocalcemia=low adjusted ca