Calcium metabolism involves three tissues (bone, intestine, kidney), three hormones (PTH, calcitonin, vitamin D), and three cell types that maintain normal calcium levels. Calcium is important for bone health, muscle function, and other processes. The daily requirement is 400-500mg for adults. PTH and calcitonin work to maintain calcium within normal ranges in plasma. Hypocalcemia can cause tetany and hypercalcemia can damage organs if severe. Tests are used to diagnose and treat imbalances.

1. Calcium Metabolism
By
Dr kabiru Salisu

2. Outline
• Introduction
• Functions of calcium
• Sources of calcium
• Daily requirement
• Absorption
• Fate of calcium in plasma
• Role of parathyroid hormone
• Role of calcitonin
• Investigation
• Hypocalcaemia
• Hypercalcaemia
• conclusion

3. Introduction
• Calcium metabolism is the process by which
body maintain normal and adequate calcium.
• Ca2+ is the most abundant cation in the body
(1–1.5 kg),
• 99% being present in bones and teeth
• The exchangeable pool; 1–2%

4. • Calcium regulation can be explain using a rule
of 3.
Three tissues; (bone, intestine, kidney)
Three hormones; (PTH, calcitonin and activated
vitamin D3)
Three cell types; (osteoblasts, osteocytes and
osteoclasts).

5. Functions of calcium
• Bone growth and remodeling
• Tooth formation
• Synaptic transmission
• Coenzyme function
• Nerve and neuromuscular transmission
• Second or third messenger in intracellular
signal transduction pathways

6. Sources of calcium
• The best natural sources include; milk and
milk product, egg, fish and bone
• Cheapest sources include; green leafy
vegetable, cereal and millet
• Other sources; beans, soya-beans, and
potato's
• Drinking water may provide up to 200mg / day
of calcium

7. Daily Requirement
• Daily intake of 400-500mg of ca2+ has been
suggested in adult.
• Physiological requirement are higher in
children, pregnant and lactating mothers

8. Absorption of calcium
From 30% to 80% of ingested calcium is
absorbed. Calcium absorption in the small
intestine occurs by both active transport and
by diffusion.
- Active transport predominates in the
duodenum and jejunum, and
- Diffusion in the ileum
Ca2+ absorption is adjusted to body needs.

10. • Factors decreasing ca2+ absorption include;
- long-chain saturated fatty acids, i.e. palmitic
acid ( forms insoluble calcium soap)
- pytic acid
- Oxalic acid
-Caffeine
-Corticosteroid

11. -Fat malabsorption
-Liver disease
-high phosphate diet

12. Fate of calcium in the plasma
• The plasma calcium is kept 2.30 and 2.60
mmol/l.
- Free or ionised (45%)
- Protein bound (45%)
- Complexes with anions – phosphate, sulphate,
citrate, lactate (10%);

13. Role of parathyroid hormone
• PTH is an 84 aa polypeptide.
• secretion - chief cells
• The serum level 10–60 pg/ml
• half-life is 2–4mn
• Serum level control via –ve feed

14. Action
PTH maintains the plasma ionized calcium level
via;
I- Osteolysis by increasing the numbers and
activity of osteoclasts as well as transport.
II-It increases proximal renal tubular
reabsorption of calcium
III- increase activity of 1α hydroxylase

15. Calcitonin
• 32 aa polypeptide
• Secretion:- parafollicular or C cells of the
thyroid gland

16. Action
• It diminishes osteolytic activity
• Inhibition of jejunal absorption of calcium
• Inhibition of tubular reabsorption and
promotion of urinary excretion calcium
• Inhibition 1 α -hydroxylase activity

17. Investigation
• Sample taking, patient should fast for at least
8hr to prevent heamo-concentration of
calcium
• No use of tourniquet ca2+/albumin are
requested

18. Calcium correction
• Corrected ca2+ (mmol/l)= (Ca) + 0.02 (40 -
albumin)
• Corrected calcium (mg/dL) = Ca (mg/dL) + 0.8
(4.0 - serum albumin [g/dL]),

19. hypocalcemia
• A corrected serum calcium concentration
<2.2 mmol/L or an ionized calcium
concentration <1.2 mmol/L

20. causes
• Vitamin D deficiency or target organ resistance;
• Dietary deficiency or malabsorption;
• liver disease
• Renal failure
• Anticonvulsants
• PTH deficiency or target organ resistance;
• Hyperphosphataemia
• Loss of calcium from the circulation: excessive
chelation.

21. Features of hypocalcaemia
- Mild hypocalcemia;
may be asymptomatic or accompanied by
nonspecific central nervous system (CNS) signs
- Chronic hypocalcaemia;
may present with mild diffuse brain disease
mimicking depression, dementia, or psychosis.
cataracts and calcification of the basal ganglia

22. Severe hypocalcaemia < 0.75 mmol/L ;
Tetany develops, esp. when an associated
alkalosis. Tetany is characterized by
paresthesias (particularly around the mouth,
lips, and tongue) and muscle spasms,
particularly of the hands, feet, and face

23. • Severe hypocalcemia can also occasionally
cause cardiac arrhythmias and heart block. An
ECG typically shows a prolonged QT interval..
• Latent neuromuscular instability can be
elicited by;
- Chvostek's sign
- Trousseau's sign

25. Treatment
• -vitamin D3 0.5-2µg/ day and -Elemental
calcium 1-2g/ day individed doses
• -Diuretics
• IV 10% calcium Gluconate

26. hypercalcaemia
• A corrected serum calcium concentration > 2.6
mmol/L. Ionized calcium concentration > 1.3
mm ol/L). Hypercalcemia is common and
dangerous in the elderly.

27. causes
• Parathyroid hormone related:
primary or secondary hyperparathyroidism
• ectopic PTH secretion.
• Vitamin D related:
vitamin D toxicity;
granulomatous dx Excess vit. D3 production.
• Malignancy: increased osteoclastic activity due to bone
destruction by primary or metastatic tumour.
• Drugs;- thiazide diuretics; lithium; vitamin A and analogues.
• Endocrine disorders: thyrotoxicosis; adrenocortical
insufficiency.

28. features
• Mild hypercalcemia
- usually asymptomatic
- Affected patients may have hypertension,
muscular weakness and irritability, mild GI
disturbances, renal colic, bone cysts, impaired
renal function (polyuria), and decreased bone
mass.

29. • Hypercalciuria and nephrolithiasis may occur .
• Bone lesion;
subperiosteal bone resorption of the hands
and a salt-and-pepper-like appearance of the
skull can be observed radiologically. Patients
with primary hyperparathyroidism usually lose
cortical bone mass in the appendicular
skeleton

30. • Severe hypercalcaemia
Severe dehydration;- vomiting, anorexia,
polyurea.
When the serum calcium is > 3 mmol/L mental
confusion can occur.
concentration may increase with dehydration,
resulting in coma and death.

31. treatment
• Depend on;
- Cause
- Rapidity of calcium raise
- Serum calcium level

32. - Rehydration
- Diuretics
- Calcitonin
- Prednisalone
- NSAID
- heamodialysis

33. Other disease associated with defect in calcium
and it metabolism include;
Rickets & Osteomalacia
osteoporosis
Renal osteodystrophy

34. Conclusion
• Calcium being most abundant cation in the
body is essential for life because of it role in
skeletal system and several metabolic activity

35. • Thank
you
for
listening

36. They Need Enough Calcium