11.10.2009 tracen.ppt 1

Trace elements

Lecture from pathological physiology

Oliver Rácz2009/2013

11.10.2009 tracen.ppt 2

Trace elements - overview

• The elements of life• Current knowledge and unanswered

questions• Iron metabolism• Zinc and copper• Vanadium, nickel, molybdenium, cobalt• Selenium• Iodine and fluorine

11.10.2009 tracen.ppt 3

Elements of life

• Main biogenic elements - 6– C, H, N, O, & P, S

• Electrolytes– Na+, K+, Mg++, Ca++ against Cl- (?)

• Trace, < 1 g with two exceptions (Fe, Zn)– metals: Fe, Zn, Cu, Mn, Mo, Cr, Co, V, Sn– most of them transition metals (complexes)– nonmetals: F, I, Se, Si, B

11.10.2009 tracen.ppt 4

Elements of life - be careful!

• Not the same as the elements found in human body:– As, Au, Pb, Hg….(contaminations)

• Strong selection:– Earth crust - O, Si, Al, Fe, Ca– Sea water ? Sea when life was arising ?– Element composition of plants resembles that of

soil

• Life is „easy“ - first half of Mendelejev table, only 4 with atomic No > 30: 34Se (79) ,42Mo (96), 50Sn (119), 53I (127)

11.10.2009 tracen.ppt 5

Trace elements - current knowledge - 1• Composition of body, tissues, cells,

O.K.• Form - metals only as complexes!

– Stable complexes are well known (heme, molybdopterin, etc.)

– Less stable complexes are difficult to study

– Added to biochemical structures after their synthesis - with exception of Se

11.10.2009 tracen.ppt 6

Trace elements - current knowledge - 2• Cycles in biosphere - natural &

influenced by human activity (ecology) influence on health

• Cycles in human body - many unanswered questions

• Clinical chemistry– Only iron status is routinely assessed– Plasmatic levels do not reflect metabolism– Indirect markers - e.g. GPX for Se

11.10.2009 tracen.ppt 7

Essential or toxic ?

+---------------------------------------------------------------------+¦ ¦ BIOGÉNNE PRVKY ¦ ¦¦ +-----------------------------------------+---------------------¦¦ ¦ HLAVNÉ ¦ELEKTROLYTY¦ STOPOVÉ ¦ TOXICKÉ ¦¦ ¦ ¦ ¦ a ¦b ¦ ¦+-----+--------+-----------+-------------+------+---------------------¦

¦ I ¦ 1H ¦ 11Na 19K ¦ 29Cu ¦ ¦ 47Ag 79Au ¦

¦ II ¦ ¦ 12Mg 20Ca ¦ 30Zn ¦ ¦ 4Be 48Cd 56Ba 80Hg ¦

¦ III ¦ ¦ ¦ ¦ 5B ¦ 5B 13Al ¦

¦ IV ¦ 6C ¦ ¦ 50Sn ¦14Si ¦ 82Pb ¦

¦ V ¦ 7N 15P ¦ ¦ 23V ¦ ¦ 33As 73Ta 83Bi ¦

¦ VI ¦ 8O 16S ¦ ¦ 24Cr 42Mo ¦34Se ¦ 24Cr 34Se 42Mo ¦

¦ VII ¦ ¦ 17Cl ¦ 25Mn ¦9F 53I¦ 9F 35Br ¦

¦ VIII¦ ¦ ¦ 26Fe27Co28Ni¦ ¦ 26Fe 27Co 28Ni ¦+---------------------------------------------------------------------+

11.10.2009 tracen.ppt 8

Supplementaion ?• RDA = recommended daily allowance • Enough for deficiency prevention• New system - DRI = daily recommended

intake– Estimated average requirement– RDA– Adequate intake– Upper limit

• YES - Fe, Zn, Cr, Se, I, F (if indicated)• NO - Cu, V, Mn, Ni, Co, Sn, Si

11.10.2009 tracen.ppt 9

Iron distribution

Total amount 4000 mg 100 %

Haemoglobin 2500 63

Myoglobin 160 4

Enzymes (catalase) 8 0,2

Stores (ferritin) 1350 33

Transport(transferrin)

5 0,12

11.10.2009 tracen.ppt 10

Iron balance

• Destruction of red cells

(0,8 % /day 20 ml)20 - 25 mg Fe/ day• 90 - 95 % recycled!• Losses only 1 - 2 mg/d

• Average diet

10 - 15 mg/ daycontrolled resorbtion

1 - 2 mg/d

Physiologic increased losses: Menstruation: 30 mg, gravidity 300 mg, lactation 180 mg

11.10.2009 tracen.ppt 11

Diagnosis ?

• Anemia - suspected sideropenia• Serum iron (m: 14 - 29, w: 12 - 23 mol/l)

is not sufficient for dg. !!!• TIBS, total iron binding capacity is a

simple and not expensive assay• Ferritin assay ? if you are rich, it is an

excellent marker of total stores (plasma: 40 - 50 ng/l)

• Transferrin assay ? (2 - 3 mg/l), fluctuating• Soluble transferrin receptor assay

11.10.2009 tracen.ppt 12

Iron binding capacity (TIBC)• 1. Iron assay from serum (16)• Excess iron added to the sample -

saturation of transferrin to 100 %• Removal on non bound iron• 2. Iron assay (64)• Saturation index = 16/64 = 0,25 (25 %)• < 0,2 = sideropenia; > 0,55 = iron

excess

11.10.2009 tracen.ppt 13

Iron deficiency and excess

• Sideropenia is common in women living in poor countries – repeated gravidities, infections, poor nutrition

• In rich countries - achlorhydria & diseases associated with chronic blood loss - kidney, gynecologic diseases, peptic ulcer

• Strict vegetarians - children• 3 stages, microcytic hypochromic

anemia is the last

11.10.2009 tracen.ppt 14

11.10.2009 tracen.ppt 15

Iron deficiency and excess

• Popeye, the brave seaman and the spinach• Mistake - spinach is not a good source of iron

(meat)• Bigger mistake - iron excess is a risk factor

of coronary heart disease• Hereditary haemochromatosis - our

european heritage (10 - 15 thousand years ago)

• Secondary haemochromatosis (Sickle cell disease and transfusions)

11.10.2009 tracen.ppt 16

Clinical manifestation of haemochromatosis

• Bronze-colored skin• Hepatomegalia, later liver cirrhosis• Painful damage of joints• Disorders of endocrine glands (e.g. diabetes bronze).• Cardiomyopathy• Chronic fatigue syndrome• Loss of libido, impotency• Oxidative stress and accelerated

atherosclerosis already in latent stage

Factors of manifestation: sex (m>w), nutrition (meat), excess alcohol consumption

11.10.2009 tracen.ppt 17

Hemochromatosisand the regulation of iron resorbtion

OMIM *235200; carrier frequency 0,045 - 0,071 (!)

Homozygotes 2 - 5/1000 HFE gene in HLA region, 1 common mutation 1999 HFE2 - long arm, ch. 1 2000 HFE3 - 7q22, transferrin receptor 2 2001 HFE4 - ch 2; SCL40A1 gene for ferroportin 2003 HAMP gene; ch 1 for hepcidin 2004 HJV gene for hemojuvelin

11.10.2009 tracen.ppt 18

Hemochromatosisand the regulation of iron resorbtion For general practice these extremely rare

conditions are not important but they are important to understand the

physiological regulation of iron resorbtion The main regulator is the hepcidin from liver

increased expression in experiment - Fe deficiency

mutation or decreased expression – Fe excess and also hemojuvelin

And iron accumulation in substantia nigra - Parkinsonism

11.10.2009 tracen.ppt 19

11.10.2009 tracen.ppt 20

11.10.2009 tracen.ppt 21

Zinc, Zn2 - 3 g; RDA 12 - 15 mg• Constituent of enzymes (cca 300)

and other proteins ( insulin crystalls)• Smell and taste receptors, ion

channels• Not a catalyst• Stabilisation of proper spatial

structure of domains - zinc fingers, regulating gene expression

11.10.2009 tracen.ppt 22

Zn - history• Nihil album (ZnO) used already in Middle

Ages ro treat eye and skin diseases• 1746 A.S. Margaff, Germany• 1869 - 1957 essential micronutrient for

plants and domestic animals, deficiency described

• 1940 - 1961 essential for man, Zn-proteins described

• 1974 RDA• Now intensive research about marginal

deficiency not only in human but also in veterinary medicine

11.10.2009 tracen.ppt 23

Zn-metalloenzymes and proteins

• DNA polymerase• Zn-Cu SOD• Retinol

dehydrogenase • Collagenase

• Metallothionein• Zn fingers• Thymulin• Steroid receptors

• NA synthesis, cell division• Antioxidant defense• Regeneration of visual

pigment• Connective tissue, vessel

wall• Transport• Gene expression• T lymfocyte

differentiation !• Endocrine functions

11.10.2009 tracen.ppt 24

Zinc, Zn - deficiency2 - 3 g; RDA 12 - 15 mg• Sources, liver, kidney, mushrooms, red beet• Small stores, phytates from cereals block

resorbtion• Marginal deficiency is probably common -

repeated infections, growth retardation• Severe deficiency

– Middle East - cereals– Alcoholism, cirrhosis, nefrotic & malabosrbtion sy.

• Hereditary disturbance of absorbtion - acrodermatitis enteropathica

11.10.2009 tracen.ppt 25

Copper, Cu 100 - 150 mg; RDA 2 - 5 mg

• Muscles, bones, liver• Active centre of many enzymes,

mainly oxidoreductases• Cu++ + e- Cu+

• Superoxddismutase, lysyloxidase, cytochromoxidase and others

• Ceruloplasmin is the main transporter of copper

11.10.2009 tracen.ppt 26

Cu metabolism, deficiency and excess

• Sources: nuts, oysters, sea fish• Binding to albumin, transcuprein and in the

liver to ceruloplasmin• Excretion through bile• Deficiency - experimental and severe

malnutrition - anemia, leukopenia, brittle bones

• Accumulation in obstructive icterus, • Intoxication - diarrhoe, liver damage

11.10.2009 tracen.ppt 27

Hereditary pathological conditions

• m. Wilson is a hereditary deficiency of coeruloplasmin - hepatolenticular degeneration – Autosomal recessive, 1/30 000 newborns– Free copper induces oxidative damage– ATP7B 13q14; 200 different mutation, 1 common– Different clinical manifestation, from mild (only

higher transaminases and Kayser-Fleischer ring to serious liver damage, hemolysis and neurological/psychiatric spts.

• KF ring = green/brown ring in cornea = deposit of Cu

11.10.2009 tracen.ppt 28

Hereditary pathological conditions

• Menkes’ kinky hair syndrome– X chromosome related, ATP7A (1/250

000)– disorder of intracellular transport of Cu– Low activity of key copper enzymes

(SOD, Cytochromoxidase, etc.)– Severe fatal disease with progressive

neurological spts., connective tissue, skin, digestion

11.10.2009 tracen.ppt 29

m. Wilson

Index Norm m. Wilson

Ceruloplazmin 1,8 – 2,5 mol/l < 1,8 mol/l

Cu – plasma 16 – 31 mol/l < 16 mol/l

Cu – liver 30 – 50 g/g 100 – 150 g/g

Cu – urine traces 100 g/d

11.10.2009 tracen.ppt 30

m. Wilson – case report

• 22 yearold man, elevated transaminases during investigation for blood donation

• All possible causes of liver disease excluded• Targeted laboratory assays - m. Wilson• Two sisters - asymptomatic form, one healthy• No Kayser – Fleischer ring• Think of it! – molecular genetic dg. is possible

11.10.2009 tracen.ppt 31

Morbus Wilson

Age S-Cu mol/l

Du-Cu mol/d

CPL g/l

Father 59 16,1 0,35 0,37

Mother 56 12,0 0,42 0,24

Son 22 2,7 1,50 0,00

Daughter1 31 2,6 0,88 0,03

Daughter2 29 15,7 0,54 0,39

Daughter3 25 3,8 1,9 0,00

11.10.2009 tracen.ppt 32

m. Wilson – case report

• Manifestation mostly in age 8 - 20 y.• Mostly liver damage, if liver failure

and mental deterioration is present, too late for therapy!– Dysartria, dysphagia, rigidity, tremor,

psychiatric symptoms• Th: penicillamin, Zn, trietyltetramin,

also liver transplantation

11.10.2009 tracen.ppt 33

Chromium, Cr 1 mg, decrease with age

• Very toxic• In complex form (picolinate) increases

insulin sensitivity• Prevention of impaired glucose

tolerance • Adjuvant therapy in Type 2 diabetes• Cr activates a step in insulin induced

signal pathway (2003)

11.10.2009 tracen.ppt 34

Vanadium, manganese, nickel cobalt, a molybdenium

• Vanadium– No deficiency in humans, intoxication is possible– Insulin like effect in vitro ?

• Manganese, nickel– No deficiency syndromes

• Cobalt– very toxic - additive to beer - cardiomypathy

– only as the constituent of vitamin B12

• Molybdenium (molybdopterin)– No deficiency in humans, intoxication is possible

11.10.2009 tracen.ppt 35

Selenium, Se

• Toxic compound (semi-condcuctors)• m. Keshan (China), cardiomyopathy• No selenium in soil, plants, food• Active center of glutathione peroxidase

(GPX), key enzyme of antioxidant defense• Involved also in iodine metabolism• Selenocysteine is incorporated to peptide

chain during synthesis

11.10.2009 tracen.ppt 36

Selenium, Se• Sources: garlic, yeast, sea fish• Marginal deficiency in many countries of

Europe (SK, H, PL, CZ)• RDA m: 70 g; w: 50 g, • Recently up to 200 g • Supplementation is recommended in

atherosclerosis and cancer prevention• In 2001 after 10 years of supplementation

significantly less prostata and colon cancer

• Not a panacea

11.10.2009 tracen.ppt 37

Iodine, I Metabolism, differentiation, CNS development• Thyroid gland and hormones (TG, T3, T4)• RDA: 100 - 200 g/d• Deficiency threatens cca 1 billion people

living in mountains but also in lowlands (far from sea),

• This country: In the past high incidence of endemic goiter

• Sources: seafood, egg yolk / salt iodidation• Strumigens (cabbage) block thyroid

metabolism• Normal urine excretion > 100 g/d• USG volume measurement of thyroid

11.10.2009 tracen.ppt 38

Requirements

Group RDA, g/d Ioduria g/l

adults and adolescents

150 100 – 200

gravidity 200 200 – 300

newborns 90 > 150

children, 6mo – 6y 90 180 – 220

children, 6 – 12y 120 100 – 200

11.10.2009 tracen.ppt 39

Consequences of iodine deficiency

Embryo abortion, malformations

Newborn increased mortality goiter, hypothyreosis psychosomatic retardation cretenism

Child goiter, hypothyreosis psychosomatic retardation cretenism

Adult goiter, hypothyreosis low IQ cretenism

11.10.2009 tracen.ppt 40

Markers of iodine metabolismIoduria, g/l Deficiency

< 20 severe

20 – 50 significant

50 – 100 mild

100 – 200 no

Volume of thyroid

ml (USG)

men < 22 ml

women < 18 ml

children according to body surface

11.10.2009 tracen.ppt 41

Fluorine, F - metabolic toxin/caries prevention• Already 0,1 mmol/l fluoride blocks bacterial

enolase• Fluoroapatite, forming 10 % tooth enamel

is more resistant as hydroxyapatite• Fluorine helps convert amorph

calciumphosphate into crystallic apatite

Tooth pasta, mouthwash, KF pills, 1 - 2 mg/d

Fluoridation of tap water