minerals by mgr

8/21/2019 Minerals by MGR

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MINERALS


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Introduction

Minerals are inorganic elements required for a variety

of functions.

They are essential for normal growth and maintenanceof the body.


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Classification of Minerals

Minerals

MacroMinerals

Traceelements

Essential

Possiblyessential

Non -essential

ToxicMinerals


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Macro Minerals

Required in excess of 100 mg/day.Eg:

Calcium

Phosphorous Magnesium

Sodium

Potassium

Chloride &

Sulfur


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Trace Elements

Required in amounts less than 100 mg/day. Further classified into 3 sub categories.

A. Essential trace elements:

Iron, Iodine, Copper, Manganese, Zinc,Molybdenum, Selenium, Flouride.

B. Possibly essential trace elements:

Nickel, Vanadium, Chromium, Barium.

C. Non-essential trace elements:

Rubidium, Silver, Gold, Bismuth


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Toxic Minerals

These are toxic to the body & should beavoided.

Eg:

Aluminium Lead

Mercury

Arsenic Cadmium


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Functions of Minerals

Minerals

OsmoticPhenomenon

Nerve MuscleConduction

Structure

Physiologicallyimportant

Eg: Hb,thyroxine

Co-factors inenzymes

Regulation ofacid-basebalance


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CALCIUM

Most abundant mineral in the body.

Total calcium in the human body1 to 1.5kg.

99% of the bodys calcium is present in bonesas hydroxyapatite.

1% in the extra-cellular fluid.


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Sources of CalciumMedium SourcesGood Sources

Small amount


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Recommended Daily Allowance of

Calcium

Adults: 500 mg/ day.

Children: 1200 mg/day.

Pregnant and lactating women: 1500 mg/day. Old age & menopausal women:

1500 mg/ day of Calcium + 20 g/ day of Vitamin D.


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Functions1) Bone mineralization.

2) Blood coagulation - prothrombin to thrombin.

3) Muscle Contractionexcitation-contraction coupling.

4) Nerve conduction.

5) Release of hormonesinsulin, parathyroid hormone,vasopressin, calcitonin, etc.

6) Second messenger.

7) Regulation of enzyme activity.

8) Action on myocardiumprolongs systole.9) Vascular permeabilitydecreases passage of serum

through capillaries.

10) Cell division.


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Absorption of Calcium

Site: 1stand 2ndpart of duodenum.

Active transportrequires energy.

Carrier proteinCalbindin.

Excretion of Calcium

Partly through kidneys. Mostly by small intestine through faeces.

Small amount of calcium may be lost in sweat.


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Factors affecting Calcium absorption

Factors stimulating

Vitamin Dinduces synthesis of CALBINDIN ->

facilitates absorption of Ca.

Parathyroid hormone (PTH)

Acidityfavors absorption

Amino acidsLysine, Arginine.

Lactoseforms soluble complexes with Ca ions.


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Factors affecting Calcium absorption

Factors inhibiting

Phytic acids (Inositol Hexaphosphate)

Oxalates.

Malabsorption syndromeCeliac disease.

Phosphates

Obstruction of bile duct

Chronic renal failure.


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Plasma Calcium Levels

Normal levels : 911 mg/dL. Calcium is present in 3 forms

1. Free / ionized/ ionic CalciumBiologically active.

2. Bound Calcium3. Complexed Calcium

- bicarbonate

- Phosphate- Lactate

- Citrate

Ionized Calcium

Bound Calcium

Complexed Calcium

50%

40%

10%


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Regulation of Calcium

3 main organs

Bone,

Kidney &

Intestine.

3 main hormones

PTH,

Vitamin D &

Calcitonin.

Homeostasis of plasma calcium is dependent on thefunction of


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Regulation (cont.)

3 major processes are involved

1. Absorption of calcium from the intestine,

mainly through the action of Vitamin D.

2. Reabsorption of Calcium from the kidney,

mainly through the action of PTH & Vitamin D.

3. Demineralization of bone mainly through

action of PTH but facilitated by Vitamin D.


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Vitamin D1. Intestine

Increases synthesis of Calbindin

Increases absorption of calcium.

2. Bones

- Increased mobilization of calcium.

- Increase in number and activity of Osteoblasts.

3. Kidney- Increased reabsorption of Calcium.

Regulation of Calcium Homeostasis


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Regulation (cont..)

Parathyroid Hormone (PTH)1. Bone

1. Demineralization.

2. Increased Osteoclasts.2. Kidney

1. Loss of Phosphates.

2. Slight increased reabsorption of Calcium.

3. Intestine (indirect action)1. Increased absorption.


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Regulation (cont.)

Calcitonin

Opposite action to PTHDecrease Calcium

levels.

Decreases reabsorption of calcium from urine.

Decreases calcium uptake of intestines.

Increased deposition of calcium in bones.


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Regulation of Calcium


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Regulation (cont..)


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Disease states

Hypercalcemia.

Hypocalcemia.


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Hypercalcemia

Increase in Serum Calcium >11g/dL.

Causes

Hyperparathyroidism

Multiple myeloma

Malignant diseases.

Prolonged immobilization.

Increased loss of phosphates in urine


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Clinical features of hypercalcemia:-

Neurological symptomsdepression, confusion,inability to concentrate.

Generalized muscle weakness.

GI problemsanorexia, abdominal pain, nausea,

vomiting and constipation.

Renalpolyuria, polydypsia, renal calculi.

Cardiac arrhthymiasshortened QT interval on ECG.

Susceptibility to fractures.


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Hypocalcemia

More serious and life threatening condition.

Serum calcium levels < 9mg/ dL.

Causes:

Hypoproteinemia. Hypoparathyroidism.

Vitamin D deficiency.

Renal tubular defects.

Pseudohypoparathyroidism.

Malnutrition.

Malabsorption.


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Clinical features of hypocalcemia:-

Enhanced neuromuscular irritability.

Neurological featurestingling, tetany, numbness.

Muscle cramps.

Cardiac arrhthymiasprolonged QT interval.

Cataracts.

Trousseaus sign & Chovstekssign.


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Phosphorus

Adult body contains about 1kg of phosphate(400 -700g).

80% found in combination with Calcium as

hydroxyapatite. Present in bone and teeth.

Present in two forms-

Organic: soft tissues; as component ofphospholipids, nucleic acids.

Inorganic: Extracellular fluid.


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Functions Constituent of bone and teeth.

Acid-base regulationmaintains the pH of bodyfluids.

Energy storage and transfereg: creatine

phosphate and ATP. Essential constituent of phospholipid of cell

membrane, nucelic acids, nucelotides.

Enzyme actionas coenzymes eg: PLP, thiaminepyrophosphate(TPP), NADP

Regulation of enzyme activityphosphorylationand dephosphorylation reactions.


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Dietary sources

Foods rich in calcium are also rich in

phosphorus.

Milk, milk products.

Egg yolk

Fish

Meat

Cereals

Leafy vegetables.


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RDA of Phosphorus

Children: 1.0 g/ day.

Adults: 800 mg/ day.

Pregnant and lactating women: 1200mg/ day.


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Metabolism of Phosphorus

Absorption:

Site: Jejunum.

About 70% of phosphate present in the diet is

absorbed.

Organic phosphates are converted into inorganic

phosphates before absorption.


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Factors affecting absorption

Factors increasing

Bile salts.

Acidity.

Parathyroid hormone 1, 25 dihydroxy

cholecalciferol.

Calcium.

Factors decreasing

High Calcium: Phosphate

ratio. (optimum1:2)

Phytates.

Alkalinity.

Magnesium

Aluminium


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Excretion of Phosphorus

Mainly by kidneys.

Urine0.6 g/ day.

90% filtered at glomerulus is reabsorbed bytubules.

Increased by parathyroid hormone.

Decreased by 1, 25 dihydroxy Vitamin D3.

Growth hormone. Cortisol.

Small amount excreted in feces (0.20.5 g/ day)


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Serum Phosphorus

Normal levels

Adults: 2.54.5 mg/dL.

Children: 46 mg/dL.


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Regulation

1, 25 dihydroxy cholecalciferol

Increases plasma phosphorus.

Increases absorption from intestine.

Increases the renal reabsorption.

Increases the mobilization from bone (at high

doses).


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Parathyroid hormone

Decreases serum phorphorus.

Decreases the renal reabsorption.

Calcitonin

Decreases serum phosphorus.

Inhibits bone resorption.

Decreases the renal reabsorption.


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Disorders

Hypophosphatemia:

Serum inorganic phosphate


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Hyperphosphatemia:

Serum phosphate >4.5mg/dL.

Causeshypoparathyroidism,

pseudohypoparathyroidism, renal failure,

rhabdomyolysis, chemotherapy Clinical features:

Tetany & seizures.


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IRON


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IRON

Normal Iron levels: 35 g/dl. Hemoproteins hemoglobin, myoglobin,

cytochromes, xanthine oxidase, catalase,tryptophan pyrrolase, peroxidase.

Non-heme Irontransferrin, ferritin,hemosiderin.

70% is seen in RBCs as constituent of

Hemoglobin. 5% of body iron is present in myoglobin.


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Sources of Iron

Rich sources: meat, liver, heart, kidney.

Good sources: Leafy vegetables, pulses,

cereals, fish, molasses.

Poor source: Milk, wheat, polished rice.


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RDA of Iron

Adult man10 mg/ day.

Menstruating woman18 mg/ day.

Pregnant & lactating woman40 mg/day.


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Functions of Iron

Iron is required for synthesis of

Hemoproteins: hemoglobin, myoglobin,

cytochromes, catalase, peroxidase, etc.

Non-Heme Iron compounds: Iron-sulfur protein offlavoproteins, Succinate dehydrogenase, NADH

dehydrogenase.

Iron helps mainly in transport, storage andutilization of oxygen.


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Absorption of Iron

Iron is mainly absorbed in the duodenum.

Normal intake of iron is 10 to 20 mg/day.

About 5 to 10 % of dietary iron is absorbed by

active transport.

Iron is mostly found in the ferric form (Fe3+) in

the foods.

Iron in the ferrous form (Fe2+) is soluble and

readily absorbed.


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Factors affecting absorption

Promoting

Acidity, Vitamin C, cysteine.

Small peptides & amino

acids. Diet with low phosphate

content.

Decreasing/ interfering

Phytates present in cereals.

Oxalates in leafy vegetables.

Diet with High phosphatecontent.

malabsorption syndrome

steatorrhea.

Patients with partial or totalgastrectomy.


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Storage of Iron

Iron is stored in liver, spleen and bone marrow

in the form of FERRITIN.

In the mucosal cells, ferritin is the temporary

storage form of iron.

A molecule of apoferritin (mol. wt 500,000)

can combine with 4000 atoms of iron.

Maximum iron content of ferritin on weight

basis is around 25 %.


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Iron Transport & Uptake

Transport form of ironTRANSFERRIN Synthesized in the liver.

Normal Plasma level200-300mg/dl.

In Iron deficiency, the level is increased.

TOTAL IRON BINDING CAPACITY (TIBC)

Normal TIBC300 - 360g/dl.

One-third is saturated with iron.

The protein bound iron in serum120mg/dl.


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Iron metabolism

IRON IS A ONE - WAY SUBSTANCE. Iron metabolism is unique as it operates in a

closed system.

It is very efficiently utilized and reutilized bythe body.

Iron is not excreted into urine.

Iron entry into the body is controlled at the

absorption level, depending on the bodyneeds.


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Mucosal Block Theory

When iron stores in the body are depleted,

absorption is enhanced. When adequate

quantity of iron is stored, absorption is

decreased.


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Iron deficiency anemia

Most common nutritional deficiency anemia. Causes: Nutritional deficiency.

Hookworm infestation.

Repeated pregnancies.

Lack of absorptionhypochlorhydria, subtotalgastrectomy.

Chronic blood losshemorrhoids, peptic ulcer,

menorrhagia. Lead poisoning.


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Iron deficiency anemia Clinical features:

Patient becomes uninterested in thesurroundingsapathy.

Prolonged iron deficiency of iron leads to

achlorhydria. Angular stomatitis, atrophy of the papilla of the

tongue.

Dysphagia- PlummerVinson syndrome

Impaired attention, irritability, lowered memory& poor performance.

Koilonychiaspoon shaped nails


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Lab findings

Hemoglobin: < 12g/dl

Serum Iron levels: Decreased 360g/dL)

Percent saturation:


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Treatment

Oral Iron is the treatment of choice.

200 mg of ferrous sulfate thrice daily for aperiod of 2 months, later continued for 3 to 6months.

Pregnant women: 100mg of Iron + 500microgram of folic acid.

Children: 20 mg of iron + 100 microgram of

folic acid. Severe anemia: Blood transfusion may be

required.


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Iron Toxicity Hemosiderosis

Microscopically visible form is hemosiderosis

Iron overload without tissue injury

Observed in patients receiving repeated blood

transfusions for eg: patients with hemolyticanemia, hemophilia.

Hemosiderosis is observed among the Bantu tribe

in South Africa. This is attributed to high intake ofiron from their staple diet corn and their habit of

cooking in iron pots.


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Hemochromatosis.

Macroscopically visible form

Iron is directly deposited in liver, spleen, pancreas

& skin.

Iron overload with tissue injury

Bronze diabetes

Bronze pigmentation of skin and tissues Cirrhosis of liver and pancreatic fibrosis.


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Koilonychia


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Menkeskinky hair Syndrome


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KayserFleischer Ring


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Cretinism


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Goitre


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Dermatitis Herpetiformis


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Dental Caries

Skeletal Fluorosis

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