CaP metabolism

2. INTRODUCTION
 Total body content = 1 – 1.5 kg
 99% present in bone and 1% in
extracellular fluid

3. Body Distribution
 25-35 mols(100g-170g)
 99% in bones (exists carbonate or
phosphate of calcium)
 0.5% in soft tissue
 0.1% in ECF
 Plasma level- 9-11mg/dl
 ionized calcium
 protein bound calcium
 complexed calcium

4. Dietary sources
 Best sources- milk and milk products
 Good sources- egg-yolk, beans, lentils,
nuts, figs, cabbage, leafy vegetables,
fish

5. Dietary requirements
Adults- 800mg/day
Pregnancy and Lactation- 1.5gm/day
Children (1-18yrs)- 0.8-1.2gm/day
Infants (<1yrs) – 300-500mg/day

6. Absorption
 present as calcium phosphate, carbonate and
tartarate in diet
 40% of average dietary calcium is absorbed
from gut
 principally from duodenum and first half of
jejunum against electrical and concentration
gradient
 Simple diffusion
 An “active” transport

7. FACTORS AFFECTING ABSORPTION
 pH of intestinal milieu
 Composition of Diet
○ High Protein Diet
○ Fatty acids
○ Phytic acid
○ Oxalates
○ Fibres
○ Minerals
○ Vitamin D
 State of health of the individual and aging
 Hormonal

8. FUNCTIONS
 Intracellular calcium
 Muscle contraction
 Release of hormones, neurotransmitter and
neuromodulators
 Activation of number of enzymes
 Glycogen metabolism
 Cell division
 Second messanger

9.  Extracellular calcium
 Maintenance of calcium level
 Formation of bone and teeth
 Blood coagulations
 Plasma membrane potential
 Membrane excitability
 Cardiac activity
 Hydrolysis of casein of milk

10. Plasma Calcium
 Serum level- 9-11mg/dl (4.5-5.5mEq/l)
 Half (5mg/dl) – ionized form
(functionally most active)
 1o% (1mg/dl) - association with citrate,
bicarbonate and/or phosphate
 40% (4-5mg/dl) – bound to protein,
mostly with albumin and partly with
globulin

11. Factor regulating plasma
calcium level
 Parathyroid Hormone
 Calcitonin
 Calcitriol

12. Excretion of Calcium
 Partly through kidney
 Mostly through Intestine
 Renal threshold = 10mg/dl

13. Clinical Disorders
Hypercalcaemia (> 11mg/dl)
1. Primary hyperparathyroidism
2. Malignant diseases
Clinical features
 Neurological symptoms such as depression,
confusion, inability to concentrate
 Muscle weakness
 GI problems such as anorexia, abdominal
pain, nausea, vomiting and constipation
 Polyuria and polydypsia
 Cardiac arrhythmias

14. Hypocalcaemia (< 8.5mg/dl)
1. Reduction in serum albumin
2. Hypoparathyroidism
3. Renal Disease and Renal Failure
4. Pseudohypoparathyroidism
5. Vitamin D deficiency
Clinical features
 Enhanced neuromuscular irritability
 Neurological features such as tingling, tetany,
numbness
 Muscle cramps
 Abnormal ECG
 cataracts

16. INTRODUCTION
 Total body content is about 1 kg
 80% is seen in bone and teeth
 10% in muscles
 Mainly intracellular and is seen in all cells

17. DISTRIBUTION
 Bones and teeth = 22000mg/100gm
 Muscle = 170 – 250mg/100gm
 Nerve = 360mg/100gm
 Whole blood = 40mg/dl

18. SOURCE
 Milk (good source)
 Cereals, Nuts and meat (moderate sources)

19. DAILY REQUIREMENT
 Infants = 240 – 400mg
 Children = 800 – 1200mg
 Adults = 800mg
 Women during pregnancy and lactation =
1.2gms

20. ABSORPTION
 90% of dietary phosphate is absorbed
 Mainly from duedenum
 Moderate amounts of fat or acid favour
absorption of phosphorus
 Stimulated by both PTH and Vit D3
 Ca:P ratio affects the absorption as well
as excretion of phosphorus
 High calcium diet and phytic acid
decrease absorption

21. FUNCTIONS
 is the constituent of bone and teeth
 Energy storage and transfer
 Acid-base balance
 Enzyme action
 constituent of phospholipids,
nucleotides/nucleic acids, lipoproteins,
 Regulation of enzyme activity

22. NORMAL RANGE
 Normal adults = 3 – 4 mg/dl
 Children = 5 – 6 mg/dl
 In serum, 40% of phosphorus exist as
free form, 50% are complexed with
Ca++, Mg++, Na+ and K+ while rest
10% are protein bound
 Fasting level is higher than postprandial

23. EXCRETION
 excreted in urine and feces
 urine excretion = 0.8 to 2.0 gm/24hr
 On a balanced diet, urine constitute
60% of total excretion

24. CLINICAL ASPECTS
Hypophosphotaemia
 Decreased intake (↓ absorption)
 Starvation
 Malnutrition
 Chronic diarrhoea
 Vitamin D deficiency
 Malabsorption
 Vomiting
 Increased cell uptake
 High dietary carbohydrate
 Respiratory alkalosis
 Insulin therapy
 Liver disease
 Increased excretion
 Diuretics
 Fanconi’ syndrome
 Hypomagnesaemia
 ↑PTH
Clinical features
Cellular function is impaired lead to
muscle pain and weakness with
respiratory failure and decreased
myocardial output
On chronic, rickets in children or
osteomalcia in adults may develop

25. Hyperphosphataemia
 Factitous hemolysis
 Increased intake
 Diet
 Vit-D
 Increased release from cells
 Diabetes mellitus
 Acidaemia
 Chemotherapy for cancer
 Rhabdomyolysis
 Increased release from bone
 Malignancy
 Renal failure
 Decreased excretion
 Renal failure
 Hypoparathyroidism
 ↑growth hormone
 Pseudohypoparathyroidism
Clinical symptoms
Elevated serum
phosphate may
cause a decrease in
serum calcium;
therfore tetany and
seizures

26. For the diagnosis of Rickets and Osteomalacia,
Ca and P estimation are done together
 ↑Ca and ↓PO4 : Primary hyperparathyroidism
 ↑Ca and ↑ PO4 : Malignancy (1° or 2°) tumour
deposits in bone, post-dialysis in renal failure
 ↓ Ca and ↑ PO4 : Hypoparathyroidism
 ↓ Ca and ↓PO4 : Vit- D deficiency