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CALCIUM AND PHOSPHATE METABOLISM
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CONTENTS Introduction Calcium and phosphorous distribution in the body Sources of calcium and phosphorus Daily requirements Functions of calcium and phosphorus Absorption of calcium and phosphorus-factors affecting Vitamin D and its role in Calcium and phosphate metabolism Role of PTH in Calcium and phosphate metabolism Influence of other hormones Calcium concentration,bone and osteoporosis Disorders of calcium and phosphate metabolism Prosthodontic Implications Summary and conclusion www.indiandentalacademy.com References
INTRODUCTION The rigidity of the skeleton which provides support and protection for soft tissues,muscle contraction,the hardness and fitness of teeth,the stability of cell membranes, activation of many hormones and last but not the least the heart beat itself is dependent on the twin minerals of the body –Calcium and phosphorus.Together,whether in ionized or unionized form,they are arguably two of the most important body components.
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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 ďƒ slow exchange of Ca++ takes place (STABLE POOL) 10.0-10.5mg/dl NORMAL SERUM CALCIUMLEVEL Remaining in soft tissues Diffusible/ ultra filterable 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 www.indiandentalacademy.com Bound to globulin 0.5mg/dl
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FUNCTIONS OF CALCIUM 1. Contributes to hardness of bone and is a major component of teeth. 2. Stabilizes 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 nonadrenaline 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 www.indiandentalacademy.com
DAILY REQUIREMENTS OF CALCIUM (WHO ESTIMATE) The recommended dietary allowance (R.D.A) for calcium is 0.5 –0.8 gms/day 6 months – 2 year 16 years to adults
= =
0.5-0.6 g/day 0.5-0.6g/day
Pregnancy and lactation Children
= =
1.0-2gm/day 800mg/day
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SOURCES OF CALCIUM -
Milk + milk products. Egg. Meat Fish Leafy vegetables Eg.Cauliflower Vegetables Eg.Beans Fruits Eg.Oranges Nuts.Eg.Almond,peanuts Bread(fortified) Hard water
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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 3-4 mg/dl in adults 5-6mg/dl in children
Organic phosphorous Remaining in the form of phospholipids & glycerophosphates
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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, 23DPG, 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 www.indiandentalacademy.com
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 faeces Ca absorbed – Ca in urine Ca lost / gained 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
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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.
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ABSORPTION OF CALCIUM AND PHOSPHOROUS It is seen that almost all the food taken in the diet is almost completely absorbed in the gut whereas 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 www.indiandentalacademy.com
FACTORS AFFECTING MUCOSAL CELL Vitamin D and Calcium Absorption Effect of previous Calcium intake and of increased calcium need Effect of pregnancy and Growth
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FACTORS AFFECTING CALCIUM ABSORPTION IN THE GUT Parathyroid hormone Effect of pH of the intestine The amount of dietary calcium and phosphorus and the Ca:P ratio Phytic acid and Phytates Effect of Oxalates Influence of Fat on calcium absorption Effect of protein and amino acids Effect of carbohydrates Seasonal effect www.indiandentalacademy.com
VITAMIN D AND ITS ROLE IN CALCIUM AND PHOSPHATE METABOLISM Vitamin D has a potent effect on Increasing Ca absorption from the intestinal tract Effects on both bone deposition and resorption Vitamin D is itself not the active substance.Instead it must be converted through a succession of reactions in the liver and kidney to the final active product 1,25Dihydroxycholecalciferol. www.indiandentalacademy.com
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ROLE OF PARATHYROID HORMONE ON CALCIUM AND PHOSPHATE METABOLISM Increased activity of the Parathyroid (PT) gland causes rapid absorption of Ca salts from the bones with the resultant hypercalcaemia an extracellular fluid.Conversely hypofunction of the PT glands cause hypocalcaemia Rise in calcium concentration is caused principally by : Rise in calcium and phosphate absorption from the bone A rapid effect in decreasing the excretion of Ca by kidneys www.indiandentalacademy.com
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The decline in phosphate concentration is caused by the effect of PTH in causing excessive phosphate excretion Ca AND P ABSORPTION FROM BONE CAUSED BY PARATHYROID HORMONE It occurs in two phases: Rapid phase:Osteolysis Slow phase:Activation of Osteoclasts EFFECT OF PTH ON Ca AND P EXCRETION BY THE KIDNEYS EFFECT OF PTH ON INTESTINAL ABSORPTION OF Ca AND P www.indiandentalacademy.com
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EFFECT OF Ca ION CONCENTRATION ON PTH SECRETION
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ROLE OF CALCITONIN IN THE REGULATION OF CALCIUM ION CONCENTRATION Calcitonin is a peptide hormone secreted by the thyroid gland (Parafollicular or ‘C’ cells) It tends to decrease plasma Ca ion concentration and has effects opposite to those of PTH Increased Ca ion concentration stimulates Calcitonin secretion which then reduces Ca ion conc. of the plasma
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OTHER HORMONES THAT EFFECT CALCIUM METABOLISM Growth Hormone Insulin Testosterone Estrogen Prolactin Thyroid hormone[T3 and T4] Steroids
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REGULATION OF CALCIUM ION CONCENTRATION IN BONE AND OSTEOPOROSIS 99% of body’s calcium is found in the skeleton Bone deposition and resorption go on concurrently Bone has three types of cells: Osteoblasts Osteocytes Osteoclasts PTH uses bone as a “bank” from which it withdraws Ca as needed to maintain the plasma Ca level www.indiandentalacademy.com
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OSTEOPOROSIS: THE BANE OF BRITTLE BONES Osteoporosis is a decrease in bone density resulting from reduced deposition of the bone's organic matrix The condition is especially prevalent in post menopausal women. After menopause women start losing 1% or more of bone density every year Because bone mass is reduced, the bones are more susceptible to fracture. There are two types of Osteoporosis: TYPE I TYPE II Treatment: Estrogen replacement therapy Ca supplementation www.indiandentalacademy.com
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EXCRETION OF CALCIUM AND PHOSPHORUS 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. Calcium of the urine is excreted as Calcium chloride and Calcium phosphate. The approximate daily turnover rates of Calcium in an adult are as follows: Intake :1000mg Intestinal absorption :350mg Secretion in GI juices :250mg Nett absorption over secretion :100mg Loss in the faeces :200mg Excretion in the urine :100mg www.indiandentalacademy.com
Phosphorus is excreted primarily through the urine. Almost two thirds of total phosphorus that is excreted is found in the urine as phosphate of various cations. Phosphorus found in the faeces is the non absorbed form of phosphorus
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DISORDERS OF CALCIUM AND PHOSPHATE METABOLISM It can be studied under the following headings: Hypercalcemia Hypocalcaemia Hyperphosphataemia Hypophosphataemia
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Hypercalcemia Causes: With normal or elevated PTH levels: Primary or tertiary hyperparathyroidism Lithium induced hyperparathyroidism Familial hypocalciuric hypercalcemia With low/suppressed PTH levels: Malignancy Multiple myeloma Elevated 1,25DHCC Thyrotoxicosis Paget’s disease Milk alkali syndrome Thiazide diuretics www.indiandentalacademy.com
CLINICAL FEATURES OF HYPERCALCEMIA “Bones,Stones and abdominal groans” Polyurea Renal calculi Polydipsia Impaired renal function Renal colic Acute dehydration Lethargy Hypertension Anorexia Nausea Dyspepsia Peptic ulceration Constipation Depression Drowsiness Impaired cognitive function www.indiandentalacademy.com
INVESTIGATIONS: Total calcium measurements……………… (Raised) Plasma phosphate………………………….(Lowered) Alkaline Phosphatase………………………(Raised) Total PTH……………………….Immunoradiometric assay SKELETAL AND RADIOGRAPHIC CHANGES: Osteitis fibrosa Localized swelling{mandible-Cystic} Chondrocalcinosis Nephrocalcinosis Subperiosteal erosions in the phalanges Pepperpot appearance of the skull in lateral cephphalograms Cystic changes www.indiandentalacademy.com
Treatment of Malignant Hypercalcemia:
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HYPOCALCEMIA CLINICAL FEATURES: Tetany Carpal Spasm Trousseau’s Sign Chvostek’s Sign Erb’s Sign TREATMENT:Intravenous calcium gluconate www.indiandentalacademy.com
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HYPOPHOSPHATAEMIA: In the presence of a plasma phosphate less than 0.4 mmol/l[normal range:0.8-1.4mmol/l],wide spread cell dysfunction and death may occur. CLINICAL FEATURES: Muscle pain and weakness,high levels of plasma creatine kinase Respiratory muscle weakness Cardiac arrhythmias Confusion,convulsions,coma Haemolysis hypercalciurea.,hypermagnesuria www.indiandentalacademy.com
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HYPERPHOSPHATAEMIA Seen in acute or chronic renal failure Metastatic calcification Secondary stimulation of parathyroid glands Pruritus
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SOME DISORDERS OF VITAMIN D: VITAMIN D DEFICIENT RICKETS In children Mainly affects the long bones in the body and the ribs Occurs due to the failure in the mineralization due to lack of adequate Ca level,the cartilagenous form of bone is said to persist The cartilage continues to proliferate and enlarge thus resulting in localized areas of cartilagenous proliferation in the form of RICKETY ROSARY,BEADED BONE FORMATION. www.indiandentalacademy.com
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The weight of the body on the uncalcified long bones result in bowing of legs-KNOCK KNEES DENTAL ABNORMALITIES: Developmental anomalies of enamel and dentine Delayed eruption of teeth Malalignment of teeth Higher caries index Wider predent9ine zone Increased amount of interglobular dentine TREATMENT: Supply adequate amounts of Ca and phosphate in diet and administration of large amounts of Vitamin D www.indiandentalacademy.com
OSTEOMALACIA Seen in adults Mainly affects the flat bones of the body Esp. seen in post 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 DENTAL FINDINGS: Severe periodontitis TREATMENT: Ca supplement Vitamin D supplement www.indiandentalacademy.com
PROSTHODONTIC CONSIDERATIONS: In Paget’s disease of the bone where the maxilla exhibits progressive enlargement the dentures may be remade periodically to accommodate the increase in size of the jaws In diabetic and osteoporotic patients particular attention must be given to accurate impressions.In addition the use of monoplane teeth in the dentures of these patients may be advocated to minimize off vertical and horizontal forces.
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ďƒ˜Patients with Ca deficiency invariably have dental abnormalities like missing teeth .The importance of a meticulous case history cannot be overstressed. ďƒ˜The diet history of elderly edentulous and post menopausal patients must be recorded with particular emphasis on adequate calcium and phosphorus supplementation.
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The placement of implants demands precise evaluation of the quality of the underlying bone.Various classifications have been proposed.One of the most important classification is as follows: MISCH BONE DENSITY CLASSIFICATION: D1:Dense cortical bone D2:Thick dense porous cortical bone on crest and coarse trabecular bone within. D3:Thin porous cortical on crest and fine trabecular bone within D4:Fine trabecular bone. D5:Immature non mineralized bone. www.indiandentalacademy.com
SUMMARY AND CONCLUSION 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 .Two points need to be kept in mind: 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.I have dealt with factors affecting Calcium and Phosphate metabolism in the body as a whole and it should not be assumed that all these factors necessarily affect the teeth. www.indiandentalacademy.com
BIBLIOGRAPHY •A.V.S.S.Rama Rao-Textbook of biochemistry,5th edition •Carl.E.Misch-Contemporary implant dentistry,2nd edition •David.B.Ferguson-Oral biosciences,1st edition •Guyton-Textbook of medical physiology,8th edition •G.Neil Jenkins-Physiology and biochemistry of the mouth,4th edition •K.D.Tripathi-Essentials of medical Pharmacology,5th edition www.indiandentalacademy.com
•Laurence Sherwood-Human physiology-from cells to system,4th edition •Malcolm Harris Michael Edgar Sajeda Meghji-Clinical Oral Science,1sr edition •Robert M Berne Matthew M Lewey-Physiology,3rd edition •T.N.Pattabhiraman-Textbook of biochemistry,2nd edition
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www.indiandentalacademy.com Leader in continuing dental education
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