Calcium metabolism disorders

1. CALCIUM
METABOLISM
DISORDERS

2. OVERVIEW :
 Calcium definition and requirement .
 Calcium metabolism regulators : VD , PTH and
calcitonin.
 Functions of calcium.
 Calcium metabolic bone diseases.
 Calcium metabolism disorders.
 CASE !!

3. WHAT IS CALCIUM ?
 Calcium is a mineral that is essential
to bone health, cardiovascular health,
muscle maintenance, circulatory
health, and blood clotting. Calcium
also acts as an enzyme activator.
While calcium is found in milk and
dairy products, it is also available from
other food sources, such as green
leafy vegetables, seafood (eating
salmon with the bones provides an
even greater dose), almonds,
blackstrap molasses, broccoli,
enriched soy and rice milk products,
figs, soybeans and tofu.

4. BODY REQUIREMENTS
 Age (in years) Calcium Requirement
 1 – 3 500mg
 4 - 8 800mg
 9 - 18 1300mg
 19 - 50 1000mg
 51+ 1500mg
 *Pregnant and lactating women are recommended
a daily calcium intake of 1000mg.

5. DIFFERENT FORMS OF CALCIUM
At any one time, most of the calcium in the body exists as the
mineral hydroxyapatite, Ca10(PO4)6(OH)2.
Calcium in the plasma:
45% in ionized form (the physiologically active form)
45% bound to proteins (predominantly albumin)
10% complexed with anions (citrate, sulfate, phosphate)
To estimate the physiologic levels of ionized calcium in states
of hypoalbuminemia:
[Ca+2]Corrected = [Ca+2]Measured + [ 0.8 (4 – Albumin) ]

6. REGULATING FACTORS
 It is regulated by :
 PTH and 1,25-(OH)2D3 on gut, kidney and bone
 Calcium receptors:
 are present in the parathyroid gland, kidney , brain
and other organs.

7. VITAMIN D METABOLISM
 The active form of vitamin D is 1,25-
dihydroxycholecalcififerol. Its production in the
kidney is catalyzed by 1 a-hydroxylase .
1 a-hydroxylase activity is increased by :
 Decreased serum Ca2+
 Increased PTH level
 Decreased serum phosphate

8. ACTION OF 1,25-
DIHYDROXYCHOLECALCIFIFEROL(CALCITRIOL)
 Increases intestinal Ca2+ absorption
 Increases intestinal phosphate absorption
 Increase renal reabsorption of Ca2+ and phosphate
 Increases resorption of bone

9. PARATHYROID HORMONE (PTH):
 it is an 84-amino-acid hormone.
Secretion:
 from the chief cells of the
parathyroid glands.
Function:
increase renal phosphate excretion , and increases plasma
calcium by:
 Increasing osteoclastic resorption of bone (occurring rapidly).
 Increasing intestinal absorption of calcium (a slower
response).
 Increasing synthesis of 1,25-(OH)2D3 (stimulating GIT
absorption).
 Increasing renal tubular reabsorption of calcium

10. REGULATION OF PTH
 Low serum [Ca+2]  Increased PTH secretion
 High serum [Ca+2]  Decreased PTH secretion

11. CALCITONIN
Produced by :
 thyroid C cell.
Function:
 Inhibition of osteoclastic bone resorption .
 Increasing the renal execration of calcium and
phosphate.
 Stimulant ??

13. INHIBITING FACTORS
 The amount of calcium consumed at
one time can also affect absorption. In
other words, calcium absorption
decreases as the amount of calcium
consumption increases in a meal.
Thus, spreading consumption of
calcium throughout your day is best.
 Age

14. CONT,
 Fiber, particularly from wheat bran, could also
prevent calcium absorption because of its content
of phytate
 dietary sodium and protein increase calcium
excretion as the amount of their intake is increased
 Caffeine has a small effect on calcium absorption. It
can temporarily increase calcium excretion and
may modestly decrease calcium absorption,

15. FUNCTIONS
 Muscle contraction
 Signal transmission
 Body structure

16. DEFICIENCY:
Deficiency of calcium levels in the body may
induce several diseases:
 Rickets disease
 Adult osteomalacia
 osteoporosis

17.  Rickets :
is a softening of bones in children potentially leading to
fractures and deformity. The predominant cause is a
vitamin D deficiency, lack calcium in the diet may also
leads to rickets
 Osteomalacia :
is the softening of the bones due to
defective bone mineralization It may
show signs as diffuse body pains, fragility
of the bones. A common cause of the disease is
deficiency in vitamin D, which is normally obtained from
the diet and/or sunlight exposure

18.  Osteoporosis
a disease characterized by low bone mass and structural
deterioration of bone tissue, leading to bone fragility and
an increased risk of fractures of the hip spine, and wrist,
leading to bone fragility. Men as well as women are
affected by osteoporosis. women had high rate to be
affected by osteoporosis

20. CALCIUM METABOLISM DISORDERS:
Calcium metabolism disorder include:
 Hypercalcemia
 Hypocalcemia
 hyperparathyrodism

21. HYPERCALCEMIA
 Is condition in which the calcium level in the body is
above the normal.
 The need of the calcium for the bone formation and
muscle contraction, releasing hormone .
 The main cause is over activity of the parathyroid
gland.
 cancer and some medication may cause over
activity of the calcium level.

22. ETIOLOGY OF HYPERCALCEMIA
 Increased GI Absorption:
Vitamin D excess
Elevated PTH
 Decreased Urinary Excretion:
Thiazide diuretics
 Increased Loss From Bone:
Elevated PTH
Hyperparathyroidism
Malignancy
Osteolytic metastases

23. COMPLICATION:
 Metastatic calcification
 Renal stones

24. HYPOCALCAEMIA
 Is a condition in which the calcium level below
The normal level
 Is caused by low level of PTH , low level of magnesium,
deficiency of vitamin D
 The kidney dysfunction play role in hypocalcuimia

25. ETIOLOGY OF THE HYPOCALCEMIA
 Decreased GI Absorption
 Poor dietary intake of calcium,impair absorption
 Increased Urinary Excretion
 Decreased Bone Resorption/Increased Mineralization
 Low PTH
 PTH resistance
 Vitamin D deficiency,

26. COMPLICATION
.
Tetany: condition of mineral imbalance in the
body that results in severe muscle spasms. usually
occurs when the concentration of calcium ions
(Ca++) in extracellular fluids below normal

27. HYPERPARATHYROIDISM.
 Hyperparathyroidism occur in two major forms:
 Primary: most common cause of hypercalceimia.it
represents autonomous production of PTH.
 Secondary:is caused by any chroinc condition
assocaited with chroinc depression in the calcuim
level.
 Tertiary hyperparathyroidism: rarely occur

28. CASE 1
a 59 year old woman with a past medical history
significant for hypertension who comes for a routine
clinic visit. She initially states that she has no
symptomatic complaints, but later in the interview
describes chronic fatigue and a mildly depressed
mood. Her exam is unremarkable. She used thiazide
diuretics as treatment for hypertension, Labs results
showed:
Calcium (total) – 11.9 mg/dL
(normal ~ 8.5-10.2 mg/dL)
Phosphate – 1.8 mg/dL
(normal ~ 2.0-4.3
mg/dL)
Albumin – 3.8 g/dL
(normal ~ 3.5-5.0
g/dL)
PTH – 124 pg/mL
(normal ~ 10-60
pg/mL)
Creatinine – 1.2 mg/dL

29. Thank You