CHUYEN HOA SAT VA ROI LOAN CHUYEN HOA SAT

(1)

S 6 2 - 2 0 1 1 TAP CHI PHONG CHONG BENH SOT RET VA CAC BENH KY SINH TRUNG 69

CHUYEN HOA SAT VA ROI LOAN CHUYEN HOA SAT

1.

KHAI Q U A T

\t CHUYEN HOA

SAT

Sat cd liSn quan m|it thiit din chuyin hda oxy, cdc dac tinh ciia sdt cho phip nd van chuySn oxy vd su tham gia ciia oxy vdo rdt nhiiu qud trinh sinh hda. Cdc trang thdi oxy hda hay gap ciia sat Id sdt hai (Fe^*) vd sdt ba (Fe^*), cdc trang thdi oxy hda cao ban gap dudi dang chdt trung gian cd ddi sdng ngdn trong mgt vdi qud trtnh oxy hda khd.

Sat cd di luc vdi cdc nguySn tii tfch diSn am nhu oxy, nita, luu huynh. Cdc nguySn td ndy cung cdp cdc dien tii tao liSn kit vdi sdt. Cdc USn kit nay ed thi cd di luc rdt cao khi d trong dai phan tvt.

Tai pH kiim hoac trung tinh sdt ton tai chu yiu dudi dang sdt ba. Khi pH acid, edn bdng dich chuyin vi phfa sdt hai. C) dang sdt ba, sdt tao cdc phuc chdt da nhdn Idn vdi ion bydroxid, H2O vd cdc ion dm khdc. Cdc phuc chdt ndy cd thi Idn din noi vugt qud kha nang hda tan ciia chdng, dan tdi ngung kit vd kit tua gdy hau qua binh ly.

Sat cd thi gdn vd anh hudng dSn cau trdc, chiic ndng rat nhiSu dai phdn td gdy hau qua cd hai cho ca thi. Di bao ve ea thi khdi cdc phan ling cd hai ndy, mdt vdi protein gdn sdt ed chiic ndng dac hieu law dir trii vd v$n chuySn sdt. Cdc protein ndy ed hai ddc tmh la: cd di luc cao vdi sdt vd d trang thdi sinh ly binh thudng khdng gdn sdt hit tdt ca cdc vi tri gdn sdt.

Tuong tdc gifta sdt vdi cdc ph6i tvt da dugc xdc dinh rd tinh chdt trong mdt vdi protein (vi du hemoglobin, myoglobm), trong khi cdc protein khdc (vf du transferm) hien dang trong qud trtnh xdc dinh.

Cdn mgt vdn dk Idn chua dugc hiiu rd trong hda sinh vi sdt Id cdc qud trinh van chuyin in vivo ciia sdt tir mgt d^ phdn tii ndy sang mgt dai phdn tvr khdc. Cd hai ea chS dk xudt dugc nhiSu nghiSn ciiu iing hd:

Su khu sdt ba thdnh sdt hai cho phip phdn ly sat, sir oxy hda sat hai thdnh sdt ba cho phip gdn sdt vdi cdc dai phan tu thfch hgp.

Gia thiit liSn quan tdi sir tao phiic vdi sdt ba bdi cdc phdn tii nhd ddc hieu ed di luc cao vdi sdt. Vi thi ndng oxy hda khii thuan Igi cho sdt ba t?i hdu hit cdc md vd vi sdt ba gdn rdt chdt vdi cdc nhdm phdi tii, kha nang Id cd co chi phdi hgp diiu hda van chuyin sdt giiia cdc phdn tii.

2. CAC PROTEIN CHlTA S A T

Sdt gdn vdi cdc protein dudi cdc dang: Tham gia trong protoporphyrin IX hoac liSn kit vdi cdc phoi tii protein khde. Phiic hgp sdt hai - protopoq)hyrin IX ggi Id hem,sdt ba- protoporphyrin IX Id hematin. Cdc protein chua hem bao gdm protem v$n chuyin oxy (hemoglobm) vd protein du trii oxy (myoglobin); Mdt vdi protem enzym chua hem nhu mgt phan cua nhdm ngoai (vi dy: tryptophan pyrrolase,catalase...).

Cdc protein gdn sdt khdng hem bao gom transferrin, ferritm, cdc enzym oxy hda khii chiia sdt t§d cdc vi trf boat dgng vd cdc protein sdt-luu huynh. Phan ndy chi trinh bdy cdc protein chiia sdt khdng hem.

(2)

70 TAP CHI PHONG CHONG BENH SOT RET VA CAC BENH KY SINH TRUNG SO 2 - 2011

Transferrin:

Day Id protein van chuyin sdt trong huyit thanh. Transferrin Id glycoprotein, dugc tdng hgp d gan, cd mgt chuoi polypeptid vdi trgng lugng phan tii 78.000 dalton, cd hai vj trf gdn sdt.

Mgt sd cac kim loai khde cd thi gdn vdi transferrin nlivmg ai luc cao nhdt la gdn vdi sdt ba. Transferrin khdng gdn vdi sdt hai. Su gdn moi mdt ion sdt ba la phu thudc tuyit ddi vdo su gdn phdi hgp mdt anion, trong trang thdi anion dd la mdt carbonat.

Transferrin + Fe^"" + COa^' • Transferrm-Fe^* - COa^'

Transferrin-Fe^^ - C03^'+ Fe^"" + COs^" • Transferrin.2 (Fe^* - COs^") Hdng sd gdn sdt ba vdi transferrin d ede lodi khde nhau Id tii 10^^-10^^ M"' Khdng c6 bdng chiing vi su hgp tdc trong viic gdn sdt d hai vi trf. 6 trang thdi sinh ly, khoang 1/9 s6 phdn tu transferrin bdo hda sdt d ea hai vi trf, 4/9 gdn sdt d mdt trong hai vi trf, 4/9 khdng gdn sdt. Hai vi tri gdn sdt mac dii tuomg tu nhau nhung khdng hodn toan gidng nhau: chung Ichdc nhau vi chuoi axid amin ciing nhu di luc vdi mdt sd kim loai khde.

Transferrin gdn vdi receptor dde hiiu trin bi mat t i bdo, giup dua protein ndy vdo ti bdo. Receptor eua transferrin Id mdt protein xuyin mang bao gdm hai tiiu dan vi, moi tiiu dom vi 90.000 dalton, ndi vdo nhau bdi cdu disulfur. Moi tiiu dom vi ed thi gdn vdi mgt phdn tii transferrin. Sir dua phiic hgp transferrin-receptor vao t i bdo phu thuge vao su phosphoryl hda receptor bdi phiic hgp Ca^"^- eahnodulin- protein kinase C. Sat dugc giai phdng ra trong mdi trudng axit cua lysosom, cdn phiic hgp receptor- apotransferrin quay trd lai mdng ti bdo, apotransferrin giai phdng ra duge svt dung lai d huyit tuong.

Lactoferrin

Laetoferrin Id mdt protein trong siia, gdn vdi sat, gan nhu transferrin, nd ciing cd hai vi trf gdn sat. Lugng sdt trong laetoferrm thay ddi nhung protem nay khdng bao gid bao hda sdt.

Vai trd cua laetoferrin lam di dang viic van chuyin sat tdi cdc vi tri receptor d ruot ciia tre em hiin dang dugc nghien ciiu. Cdc nghiin ciiu khdc tim hiiu vi chiic nang ciia lactoferrin trong viic khdng khudn, bao vi tre sa sinh khdi cdc nhiim triing da day-rudt. Cdc vi sinh v?t edn sdt di tdi ban va boat ddng. Su cd mat ciia lactoferrin khdng bao hda hodn toan sdt dan toi viic gdn nhanh chdng cdc ion sdt tu do, lie chi su sinh trudng eua vi khudn bdi ngdn can viec cung cdp sdt cho vi khudn. Cdc vi khudn khde nhu E.coU tao ra cdc ehdt tao phuc vdi sdt, vi v$y cd khd ndng phan chia du cd lactoferrin, vi cdc chat tao phiic van chuyin sdt dac hiiu vdi vi khuan.

Ferritin

Ferritin Id protein du tru sdt, bao gdm mgt lap vd polypeptid bin ngodi dudng kfnh 130 A°, vdi ldi chiia hydroxyd- sdt ba- phosphat dudng kfnh 60 A° Apoferritin bao gdm 24 tilu dom vi, la hon hgp eua ede chuoi H (21.000 dalton) vdi chuoi L (19.000 dalton), vdi ti le dc chuoi khde nhau tao ra ede dang isoprotein.

Ti li sdt vdi protein trong ferritin khdng hdng dinh, vi protein ndy cd kha ndng bdt gift vd giai phdng sdt theo nhu cau sinh ly. Mdt phdn tu ferritin cd kha nang chiia 4.500 nguyin tir sdt, nhung no thudng chiia ft ban 3.000. Tren bi mat ferritin ed cdc kSnh cho phep tfch luy v^

giai phdng sdt. Khi thira sdt, kha nang du trii cua apoferritin mdi dugc tong hgp cd thi qud t^l

(3)

S6 2 - 2011 TAP CHI P H 6 N G CHdNG BENH S 6 T RET VA CAC BENH KY SINH TRUNG ^ 1

diiu nay dan tdi ldng dgng sdt canh ede phdn tu ferritin hinh cau. Cdc can ldng dgng sdt khdng hinh thu dugc ggi Id hemosiderin.

Chuoi H eua ferritin oxy hda sdt hai thdnh sdt ba. Ferritin d ede md khde nhau ciia cung mgt lodi cd tfnh di chuyin diin di khde nhau, tuomg tu nhu mau hinh diin di eua cdc isoenzym.

Trong mdt vdi md, ferritin binh cau tao ede mang hinh ludi cd thi xdc dinh dugc bdng kmh hiin vi diin tu.

Cac protein chva sdt khong hem khac

Nhiiu protein chua sat khdng hem khdc ed liin quan tdi cac qud trtnh enzym, phdn Idn Id cdc CO chi oxy hda. Cdc ddc diim cdu true eua phdi tu gdn sdt chua dugc biit ddy du, trir mdt sd thdnh phan eua chuoi van chuyin diin td trong ty thi. Cdc protein chua sdt tham gia van chuyin diin tvr ggi law cdc ferredoxin, ed bdn typ chmh. Typ I (vf du nebredoxin) nhd nhat, chi tim thay trong vi khudn, bao gdm mdt chuoi polypeptidnhor ed trgng lugng phdn tur khoang 6.000; chiia nguyin tu sat gdn vdi bdn gdc cystein riing re. Typ II bao gdm ede ferredoxin tim thdy trong md dgng vat vd thuc vdt, moi nguyin tvr sdt trong hai nguySn tu sat tim thay trong dd gan vdi hai gdc cystein riSng re va chia si 2 anion sulfiir. Typ III la ede protein sdt luu huynh phdc tap nhdt, chiia bdn nguyin tvr sdt, moi nguySn td gan vdi mdt gdc cystein riSng biet vd chia si 3 ion sulfur vdi cdc nguySn tu sdt bSn canh tao cau true gidng hinh lap phuang. Typ IV cd 3 nguySn tu sat, moi nguySn tvr gan vdi 2 gdc cystein riSng re vd chia si 2 anion sulfiir tao hinh nhan phdng. Thi ndng oxy hda khii ciia cdc ferredoxin khde nhau nay thay ddi rat nhiiu vd mdt phdn ddc lap vdi mdi trudng cua chuoi polypeptid bao phu cdc nhdm sat luu huynh ndy.

3. PHAN BO

SAT

VA

CAN BANG SAT

Mgt ngudi dan dng 70 kg ed khodng 3-4g sdt, trong dd chi khoang 0,1% (3- 4 mg) trong huyit thanh dudi dang gdn vdi transferrin. Phdn Idn sdt (khoang 2/3 tiic khodng 2,5g) d trong hemoglobin. Khoang 0,5g sdt dudi dang sdt hogt dgng trong cdc protein vd enzym khdc. Sdt du trii d ddn dng khde manh khoang 0,5 2g dudi dang ferritin trong cdc ea quan nhu gan.

Bdng 1. Phdn bd sdt & ngudi ddn dng 70 kh Idch, tuy xuang. O tri em, thiiu nien

vd phu nii trong do tudi sinh san hau nhu khdng cd sdt du trii. So vdi mdt lugng Idn sdt du trii vd sdt cd chuc ndng, lugng mdu van chuyin trong sdt dudi d?ing kit hgp Transferrin (khoang 4mg) vd lugng sdt hdp thu vd bdi tiit mdt ngdy (khoang 1 mg) la rdt nhd. Nhu cdu sat hdng ngdy cho tdng hgp mdi Hb Id 25mg, rd rdng Id vugt qud lugng sdt hdp thu hang ngdy nhiiu l^n.

Vi viec hdp tbv sdt chi ed thi tang ISn d mdt muc dg nhdt djnh yd viec diiu hda bdi tiit sdt Id khd khdn, nhu cau sdt chi cd thi ddp img duge bdi mire du trii sdt trong thdi gian ddi vd viic tdi sd dung sdt mgt cdch ed bifu qud.

Hb Mb Transferrin Ferritin ma

Ferritin h u y i t thanh Cdc enzym COng

G a m 2,5 0,15 0,003

1,0 0,0001

0,02 3,7

%

6 8 4 0,1 2 7 0,004

0,6 100

(4)

72 TAP CHI PHONG CHONG BENH SOT RET VA CAC BENH KY SINH TRUNG SO2-2011

Hafp thu Sat trong thuTc 3n

Mau Tong hdp Hb

Fe3+ Fe2+

lOmg/ngay

Sat trong Hb hong cau 2500 mg

1mg/ngay

TBNM ruot

Phan Img/ngay

Huyet tUdng

25mg/ngay 25mg/ngay

Tuy xUdng Nguyen hong cau

125 mg

' — 25mg/ngay Lach

Img/ngay Img/ngay

Tieu huyet 500 mg TB LVNM Te bao gan 500mg

Gan

Bai tiet Van chuyen DirtrCr

Hinh 1: Can bang sat

TBNM rudt: t i bao niim mac rudt TB LVNM: t i bdo liin vdng ndi md

4.

HAP THU SAT

Sdt dugc hdp thu d td trdng vd phdn trin hong trang dudi dang sdt hai. Tuy nhiSn, sdt trong thiic an chu yiu dudi dang sdt ba (trir phan sdt gdn hem), nin dau tiin nd can dugc khii thdnh sdt bai. Thudng chi khodng 10% sdt trong thiic an, tiic Id khoang lmg/24 gid duge hap thu.

Su hdp thu sdt phu thudc vdo rdt nhiSu ySu td: thdi quen an udng,chat lie ehS vd chat ldm tdng hap thu sdt trong thuc an. Su ndu chm thiic an ldm cho viic phd va nhiing phdi tit gdn sdt de ddng. pH thap ciia da day cho phep khd sat ba thdnh sdt hai, ldm phdn ly sdt khoi phdi tii. Chuc ndng da day khdng binh thudng ldm gidm ddng ki lugng sat dugc hdp thu. Cdc cofactor protein tvr d?i day vd tuy duge cho Id lam thu?ln Igi cho su hdp thu sdt d rudt non.

Cdc yiu td ldm tang hip thu sdt bao gdm thiic an chua nhiiu thit (ti li sdt hai cao), vitamin C, cdc axit ed tfnh khvr trong rau qua. Cdc yiu td lie chi Id an chay, thiiu vitamin cung nhu tao cdc phiic cbura sat khdng hap thif nhu trong trudng hgp udng nhiiu cd phi, chfe, nude nggt cd ga.

Ca chi hap thu sat cdn can ldm dugc ldm sdng td d tdt ea cdc budc. Sdt di vdo ti bdo niim mac rudt non dudi dan ion tu do bode hem, sdt se dugc giai phdng ra d nhdn porphyrin trong bdo tvromg t i bdo niim mac rudt. Lugng bicarbonat Idn do tuy bdi tiit ra trung hda tfnh acid eua khdi thiic an tir da day tdi, ldm de ddng chi viic oxy hda sdt hai thanh sdt ba. Trong ti bdo niim mac rugt, sdt hai dugc oxy hda thdnh sdt ba bdi endooxidasel (ceruloplasmin).

Dudi dang sdt ba, sdt ed thi gdn vdi transferrin, di vdo tudn hodn tdi cdc ea quan tiiu thv vd du trii sdt. Rdo can chfnh cho viic hdp thu sdt khdng phai la d b i mat riim bdn chai ciia te bdo niim mac rudt. Bdt ki nhu cdu sdt eua ca thi Id bao nhiiu, mgt lugng Idn sdt trong thuc an se

(5)

so 2 - 2011 TAP CHI P H 6 N G C H 6 N G BENH S6T RET VA CAC BENH KY SINH TRUNG 73

di vdo te bdo niim mac rudt. Viec diSu hda chuyin hda sdt xay ra giiia te bao niim mac rudt vd mao m?ich. Khi c6 suy giam sdt, lugng chit v$n chuyin tang ISn; d ngudi thira sdt lugng chat v$n chuyin se giam ddng ki, Khi cd thira sat so vdi nhu cdu ca thi, mdt lugng Idn apoferritin dugc tdng hgp trong t i bdo niSm mac rudt dS giii sat trong te bao niim mac rudt, ngdn can su vdn chuyin sat vdo mao mach. Khi t i bdo niim mac rudt chit di, lugng sdt thira ndy se di vdo trong ldng rudt ma khdng duge hdp thu. Khi thiiu hut sdt, apoferritm se khdng duge tong hgp vd sat se dugc v|in chuyin vdo trong ca thi. Sdt van chuyin vdo mao mach se duge bdt giii bdi transferrm.

L6ng ta trang T0bdo niem mac rugt Mao mach

Sat trong thuTc 3n

Mat di theo sU bong TB

Khdng diTcJc hap thu

Vao TB khi TB phan chia

Hap thu

Hinh 2. Diiu hda hdp thu sdt tai niim mac rudt

Ca sir du trii sdt tam thdi d rugt ciing nhu ca chi diiu hda bu trir eua protem van chuyin sdt transferrin cho phip hdp thu sdt ddp iing vdi nhu cdu sdt hiin thdi cua ea thi. Khi thiiu mdu thiiu sdt hoac thiiu oxy dan tdi tdng hdp thu vd tdng kha ndng van chuySn qua tang tdng hgp transferrin vd tdng tdng hgp receptor transferrin. Tuy nbiSn svr chinh lich qud miic so vdi nhu cdu khdng thi bii trir duge bdi cdc ea chi diiu hda trong mdt thdi gian ddi. Su thiiu hut sdt ndng thi tang hdp thu khdng thi thda ddng; trdi lai khi thira sdt ea che diiu hda bdi tiit tfch cue sdt cung khdng de ddng.

5. VAN CHUYEN S A T

Sdt duge van chuyin tir dudng tiiu hda (vi trf hdp thu) tdi cdc ea quan du trii nhu gan, Idch, tuy xuang vd tdt ea ca quan tiiu thu khdc dudi dang gdn ddc hiiu eua sdt ba vdi transferrin. Cdc t i bdo cua ca quan dfch diiu hda su hdp thu sdt qua viic tdng hgp cdc receptor transferrin trin bi mat t i bdo theo nhu cau co thi. Trong trudng hgp qud tdi sdt, mgt lugng ddng ki sdt gdn khdng ddc hiiu vdi ede protem van cliuyin khde nhu albumin niu cdc vi trf gdn ddc hiiu cua transferrin dd bdo hda. Trudng hgp chi do dn ed nhiiu sdt gdn hem, co chi van chuyin qua transferrin cd thi duge thay thi bdi gdn phuc hgp sdt bai-hem vdi haptoglobin ho|c hemopexin.

(6)

Kha nang van chuyin eua transferrin thudng bao hda 15-45%. Ty li phdn tram cao hom chi ra su ed mat cua qud tai sat thuc su. Ty li phan tram thap horn liin quan tdi ddc tinh trang do thiiu hut sat hoac do rdi loan phdn bd su dimg sdt. Su xdc dinh miic bao hda ciia transferrin hien nay dugc ua thfch hom viec xdc dinh ndng do sdt vi nd cho phip loai trir cdc yiu td nhieu do cdc ki thuat lay mau khde nhau, tinh trang nude dien giai eua benh nhdn, sir dao dgng khdng do sdt eua ndng do transferrin. Tuy nhiin miie bdo hda transferrin cung nhu ndng do sat huyit tuomg khdng duge xem nhu mdt chi diim thfch hgp cho lugng sdt ciia todn CO thi vi su dao ddng tam thai cua nd vd mdi tuomg quan ft vdi lugng sdt du trii.

d - D U T R t r s A T

Protein du trii sat ferritin Id mdt chi diim ciia du trii sdt ciia ca thi. Sdt duge bdt giu bdi cdc ti bdo tiSu thu vd tS bdo du trii sdt qua receptor transferrin trin mdng t i bao; mat do ciia receptor transferrin duge diSu hda theo nhu cau sdt bode liSn quan tdi du tru sat. NSu suy giam sat trong te bdo xuat hiin, su tdng hgp receptor tang de tang lugng sdt cho t i bao. Mat khdc,niu lugng sdt cho t i bao qud nhiiu, kfch thfch viic tdng hgp apoferritin, tiic la protein du tru sdt. Du tru sat dudi dang khdng ddc ddi hdi su cd mat cua lap do protein nay. Mgt lugng nhd nhung dai diin cho ferritin trong t i bdo duge giai phdng vao trong tudn hodn, do la If do tai sao ndng do ferritin huyit thanh cd thi duge diing nhu mdt phip do ludng dac trung cho ferritin trong t i bdo va vi vay cho lugng sdt du tru trong hdu hSt cdc tinh hudng liSn quan dSn chuySn hda sdt.

Mdi tuomg quan chat che giiia ferritin huyit thanh vdi sat du trii chi dp dung trong cdc trudng hgp:

- Chuyen hda sdt binh thudng

Tat ea ede giai doan cua tbiSu hut sat

Tat ca cdc dang eua qud tai sdt thuc su,trir cdc giai doan mugn ed tdn thuang gan thii phdt - Diiu tri sdt dudng udng

Mdi tuomg quan nay khdng cdn dung trong cac trudng hgp sau:

- Dung sdt dudng tiim tinh mach

- Cdc rdi loan phdn bd va sd dimg sdt nhu trong viSm man tfnh hoac ede khdi u

Theo kinh nghiSm, ndng do ferritin buySt thanh la 1 |ig/L tuomg duomg vdi lugng sdt du trii la 10 mg. Qui tdc nay dp dung vdi ndng do ferritin tdi 200 ng /L

Di ddnh gid lugng sdt du trii, sinh thiit tuy xuang vd gan thudng khdng can thiit trii khi cdc benh khdc anh hudn tdi ea quan nay edn duge loai trir. Vi su dao ddng theo nhip ngdy dSm vd mdt phdn nhd eua sdt huyit thanh cd liSn quan tdi sdt du trii, sir xdc dinh lugng sdt huyit thanh rd rdng khdng thfch hgp cho viec ddnh gid sdt du trd.

7. NHU CAu S A T

Nhu cdu sdt eua ea thi cd thi dugc xem nhu ti li nghicb vdi lugng sdt-^u trii, vi nhu cdu sdt, vf du nhu cho viic tdng hgp mdi Hb, cd thi de dang ddp iing dugc niu nhu du trii sdt thoa ddng. Diiu ndy nghia la trong trudng hgp ndng do ferritin huyit thanh binh thudng bode cao, su hdp thu mdt lugng sdt hang ngdy la Inig Id du bu vdi lugng sdt mdt di cung khoang mgt lugng tuomg tu. Diiu tri sdt thay thi Id ehdng chi dinh trong cdc trudng hgp ndy, trir trudng hgp diiu tri erythpoietin.

(7)

S62-2011 TAP CHI P H 6 N G C H 6 N G BENH SOT RET VA CAC BENH KY SINH TRUNG 75

Trong trudng hgp suy giam sdt tiim tdng bode rd rang trin lam sdng, nhu cdu sdt ed thi lin tdi 5 mg/ngdy. Trong khi ferritin do lugng sdt du trii gidm xudng trong cdc trudng hgp ndy, receptor transferrin khdng chi ddng thdi tdng tdng hgp do tdng nhu cdu sdt md cdn dugc gidi phdng vdo huyit tuorn^ dudi dang receptor transferrin hda tan. Vi vay, thim vdo cdc phip dinh lugng sdt du trii vd sdt van chuyin, viic dinh lugng receptor transferrin se ddng vai trd Idn born, ddc biit trong cdc trudng hgp rdi loan phuc tap ban cua chuyin hda sdt, vf du cdc rdi loan huy ddng sdt.

Ddnh gia nhu cau sdt cung quan trgng d cdc ddi tugng ed nguy ca thiiu hut sdt tiim tdng nhu tre em, thiiu niin, phu nii thai ki cdn kinh nguyit, van ddng viin diin kinh, nhiing ngudi cho mdu. Dua trin cdc hiiu biit hiin nay, xdc dinh ferritin huyit thanh vd muc bdo hda transferrin cho phep ddnh gid thda ddng thiiu hut sdt trong cdc tinh hudng trin.

8. BAI TIET SAT VA MAT SAT

Do sdt CO di lire cao vdi cdc dai phdn tur ddc hiiu bode khdng ddc hieu ddn tdi khdng cd lugng mudi sat tvr do ddng ki, vi vdy sdt khdng mdt di qua nhiing con dudng bdi tiit thdng thudng. Su bdi tiSt sdt xay ra do sir bong di binh thudng cua cdc md khdng dugc su dung lai, vf du ti bdo niim mac rudt vd t i bdo da. Lugng sdt bai tiit hang ngdy khoang Img. Phu nii cd kmh mdt di mdt lugng sdt hang thdng tu 15-30 mg. Lugng mdt ndy ed thi bii trir bdng tdng hdp thu sdt, trir khi cdc nguy co khdc cua thiiu hut sdt xudt hiin nhu chi do dn udng khdng ddy du, ngudi thudng xuyin cho mdu.

9. CAC ROI L O i ^ CHUYEN HOA S A T Thieu sdt:

Thiiu sat d nhiing giai doan khde nhau Id roi loan thudng gap nhdt bode de bi bd qua nhat bode khdng dugc xdc dinh dung cua chuyin hda sdt. Thiiu sat cd thi la tinh trang suy dinh dudng phd biin nhat. Trin thi gidi ti li ngudi mdc thiiu sat ft nhat la 1 ty ngudi. C) ede nude phdt triin cdc dang thiiu hut sdt ndng trd nSn biSm gap bom trong vdi thap ki gdn ddy.

Tuy nhiSn,d nhiing nude ndy ft nhdt 50% phu nii trong do tudi sinh nd ed thiiu sdt tiim tdng bode tiin tiim tdng. Phu nii cd thai hdu hit ludn cd thiiu sdt, ft nhdt 10% sd ndy biiu hien thiiu sdt rd ret trSn lam sang. Thiiu sat thudng do thdi quen an udng khdng ddy du hom Id cdc If do kinh ti, dac biet nhiing ngudi ed nguy ea, ldm cho thiiu sdt trd thdnh mdt vdn dk vi sue khde ngay ea d nhiing nude cdng nghiep gidu cd.

Thiiu sdt dugc chia lam 3 giai doan:

Thiiu sdt tiin tiim tang duac dinh nghia la sir thiiu hut lugng sat du trii vd vi vay ed thi phdt hiin duge bdng su gidm ndng do ferritin huyit thanh cung nhu su gidm sdt d cdc co quan du trd ed thi phdt hiin dugc bdng khdm nghiim md binh hgc. Trong giai doan ndy, sir huy dgng sdt v$n chuyin van hodn todn binh thudng vd vi vdy sdt cung cdp cho tao hdng cdu ciing binh thudng. Sir tdng hgp receptor transferrin, transferrin ciing nhu su hdp thu sdt" d rudt trong phdn Idn ede trudng hgp d gidi ban binh thudng bode tdng nhe do phdn iing bu trir. Vi mat ldm sdng.cdc benh nhdn nay khdng cd rdi loan gi.

Thiiu sdt tiim tdng: bSn canh thiiu sdt du trd Id suy giam sdt van chuyin, cd thi phdt hien duge bdng ndng dg ferritin huyit tuomg thdp vd muc bdo hda transferrm giam. Su cung cip sdt cho tgo bong cau cdn thda ddng trong giai doan ndy nSn chua cd thiSu mdu. Tuy nhiSn,

(8)

76 TAP CHI PHONG CHONG BENH SOT RET VA CAC BENH KY SINH TRUNG S 6 2 - 2011

cac trieu chiing khdng dac hieu cua thiiu sat nhu met mdi, giam sinh nang lugng va cdc div hiiu than kinh tdm thdn khac nhau cd thi xay ra trong giai doan ndy do hau qua ciia thiiu hut sat cua cdc ca quan liin quan khdc nhau va cua cac protein-enzym ehiia sat.

- Thieu sat lam sdng: Sat cung cdp cho tao hdng cdu khong du cho sinh tdng hgp hemoglobin. Sau mdt thdi gian nhat dinh, tuomg iing vdi ddi sdng hong cau, thiiu mau nhugc sac hdng cau nhd xuat hiin. Giai doan ndy la thiiu mdu cd biiu hiin lam sdng ro rdng vd thiiu mdu ed thi kem theo nhiing dau biiu khdc do suy giam sat trdm trgng. Trong khi cdc dang nhe eua thiiu hut sdt gap phd biin d cdc binh nhdn tri, ddc biit nhdm ngudi ed nguy ca, cdc dang ndng ed thi do cdc benh todn than nghiim trgng, vf du nhu ung thu chay mau, rdi loan da ddy, rugt liin quan tdi kem bap thu. Cdc trudng hgp nay ddi hdi tim kiim nguySn nhdn bom Id xip vdo nhdm ddi tugng ed nguy ea thiiu hut sdt diin hinh nhu thiiu niin, phu nii do tudi sinh nd, phu nu cd thai, van dgng viSn diin kinh, ngudi an chay, ngudi cho mdu.

Diiu quan trgng phai nhd la tat ca cdc dang thiiu sdt ed thi xdc dinh duge bang ndng do ferritin huyit thanh vdi do nhay vd do ddc hiiu lam sdng cao. Vi vay cdc kham nghiim xdm nhap liin quan din sat du trii d md nhu tuy xuang, gan cd thi trdnh dugc. Cdc xit nghiim mdu khdc nhu receptor transferrin hda tan bode protoporphyrin kem cung Id cdc chi diim nhay cua sinh hdng cdu thiiu sdt, chdng bdt ddu tang trong giai dogn thiiu sdt tiim tdng. Tuy nhiin, ede thdng sd nay cd thi tang trong cdc trudng hgp sii dung sdt bdt thudng va cdc trudng hgp tang nhu cdu sdt do cdc nguySn nhdn khac nhau. Vi v$y,cdc thdng sd ndy khdng dac hieu cho thiiu sdt. Ciing tuomg tu nhu vay, ndng do sdt huyit thanh vd muc bao hda transferrin khdng thi gidp chudn dodn phdn biet giura thiiu hut sdt thuc sir vd rdi. loan phdn bd sdt.

Tien tiem tang

NLir>12 Nam >15

3,6 - 3,8 Giam sat dt/ trii'

Thie'u sat

Tiem tang Ferritin (ng/L)

N[jr>12 Nam >15 Transferrin (g/L)

>3,8 Giam s i t di^r tru' Giam sit v$n chuyen

Lam sang

Nur<12 Nam <15

» 3 , 8 Giam s i t di/ trir Giam sat v|in chuyen

Giam sat trong Hb

Phan loai thieu s5t dwa tren viec dinh lirgng ferritin,Hb vjk transferrin Thira sdt:

Thira sdt thuc su dugc xdc dinh trin su tang ndng do ferritin huyit thanh,tdng mdc bao hda transferrin yd ed thi dua trin cdc dii lieu md benh hgc ed su ldng dgng sdt d tuy xuang hay gan. Thira sdt chu yiu do 3 nhdm nguyen nhdn chmh sau ddy:

(9)

S6 2 - 2011 TAP CHI P H 6 N G C H 6 N G B|NH S6T RET VA CAC BENH KY SINH TRUNG 77

- Nhiem sac td sdt tiem phdt do di truySn gay ra tang hap thu sat mdt cdch khdng thfch ddng mac dd sat du trii da thda ddng hay tham chf dd tang.

Thieu mdu man tfnh do sinh hdng cdu khdng hiiu qua hoac huyit tdn ed thi ciing dan tdi tdng hap thu sdt do hau qua eua thiiu mdu vd oxy; vi vay sau mdt thdi gian thira sdt cd thi xudt hien.

Thira sdt trong trudng hgp binh mdn tfnh ed liin quan tdi thieu mdu do do thua sat ndng ban lin do truyin mdu lap lai nhiiu Idn bode diiu tri sdt khdng dung chi dinh cua thay thudc.

Tdt ca cdc trudng hgp nSu trSn gay thira sdt du trii; tuy nhiSn nhiem sdc td sdt USn phdt ddng mdt vai trd ddc biet quan trgng vi thira sat vira phdi ed thS ddn dSn ldng dgng sat benh ly d nhu md gan, ea tim, tuy. Tdt ca cdc dang thira sdt thu phdt mdi ddu anh hudng tdi cdc tS bdo liSn vdng ndi md trong gan, Idch, tuy xuomg trong khi tdn thuang ca quan thu phdt thudng chi xay ra vdo giai doan mugn.

Trong tdt ca ede trudng hgp thira sdt thuc sir, trir trudng hgp thira sdt thuc su, trir trudng hgp diiu tri sdt dudng tiSm tihh mach bode trudng hgp ed tdn thuong ea quan thu phdt, mdi tuomg quan ddc trung giiia ndng do ferritm huyit thanh vd sdt du trii dugc dp dung. Mdi tuomg quan ndy ciing duge dp dung di theo ddi diiu tri buy ddng sdt bdng cdc chdt tao phuc hay cbfeb mdu, vf du d ede benh nhdn nhiem sdc td sdt. Trong khi sinh thiit mdt lan dk xdc dinh md benh hgc ldng dgng sdt d cdc md cung nhu phdt hien tdn thuang ca quan Id edn thiet trong trudng hgp nhiem sdc td sdt tiSn phdt vd thii phdt, thi cdc sinh thiit vdi muc dfch theo ddi trong qud trtnh diiu tri huy ddng sdt Id khdng ddi hdi.

Di khdng dinh chdn dodn nhiem sdc td sdt di truyin, cdc phuang phdp sinh hgc phdn tu gan ddy dd trd thdnh hiiu dung cho viec phdt hien cdc tdn thuang gen HLA-H.

Ndng do ferritin huyit thanh tdng khdng phdi chi liSn quan din chudn dodn thua sdt md edn cd thi gap trong cdc rdi logn phdn bd sdt. Trong cdc tinh huong ndy, ndng dg ferritm khdng edn phan dnh sdt du trd. Thira sdt thuc su cd thi dugc phdn biet vdi rdi loan phdn bd sdt dvra trSn muc bdo hda transferrin tdng.

Tdy theo nguyin nhdn cua thira sdt, su tdng hgp cdc receptor transferrin duge diiu hda theo hogt ddng tao bdng cdu trong moi trudng hgp. Ndng dd receptor transferrin dugc diiu hda theo boat dgng tgo hdng cau trong moi trudng hgp. Ndng do receptor transferrm cung tdng trong tdt ca cdc trudng hgp tan huyit do phan iing bti trir tdng boat ddng tgo hdng cau, tuong ung vdi nhu cdu sdt tang. Mat khdc, cdc binh tuy xuang vdi su sinh hdng cdu khdng hieu qua vd cdc trudng hgp nhiem sdc td sdt cd xu hudng gidm nhu cau sdt thi nong dd receptor transferrin thap hom.

C^c r6i lo^n phan bo sdt:

Rdi logn phan bd sdt dvr trii hay gdp d cdc bfnh man tfnh (cdc khdi u dc tfnh,cdc viSm nhiem man tfnh). Rdi loan ndy liin quan tdi thira sdt du trii tuomg ddi cung nhu suy giam sdt van chuyin vd sdt ed chiic ndng. Trong cdc trudng hgp ndy cdc xit nghiim diing chdn dodn r6i loan chuyin hda sdt cd thi khdng ddp ung dugc vd khd ddnh gid vi ede If do sau:

(10)

78 TAP CHI PHONG CHONG BENH S 6 T RET VA CAC BENH KY SINH TRUNG SO 2 - 2011

- Cdc khdi u ed nhu cdu sat cao

Tdng hgp mgt phan cdc isoferritin acid cam iing bdi benh Hoai tii cdc ca quan du trii sdt lam giai phdng liSn tuc ferritin

Tdt ea ede ea chi ndy dan din thuc ti Id mdi tuomg quan dgc trung giiia ndng do ferritin va sat du trii khdng edn ed gid tri niia. Cdc ndng do ferritin cao thudmg chi diSm cho lugng sat du tru la cao hom sdt du trir thuc cd. Trdi vdi thira sdt thuc su ,ndng do sdt huyet thanh vd miic bao hda transferrin giam mgt cdch diin hinh, vi vay phan dnh huy dgng sat cho cdc qua trtnh tdng hgp kim. Niu diiu ndy dan din thiiu mdu nhugc sac hdng cau nhd, nd ciing ft khi nham vdi thiiu mdu do thiiu sdt. Chdn doan phan biit giiia thiiu mdu eua binh man tfnh vdi thiiu mdu do thiiu sdt thuc sir vi vay la mgt trong cdc chi dinh chfnh eua viic dinh lugng ndng dd ferritin huyit thanh.

Trong phan Idn nhiing trudng hgp rdi logn phan bd sdt niu trSn, su cung cap sat cho cdc tS bdo tao bdng cau giam tuomg ddi cung vdi su giam boat ddng tgo hdng cau. Tuomg ung,su tdng hgp receptor transferrin nhin chung khdng thay ddi hoac giam vd ndng do transferrin thudng giam. Tuy nhiSn trong trudng hgp ede khdi u phdt triSn nhanh vdi nhu cau sdt cua ti bdo u cao, ndng do receptor transferrin hda tan cd thi tang.

Roi loan su dung s^t:

Trong cdc trudng hgp sdt du trii binh thudmg vd phan bd sat binh thudmg dugc xdc dinh bdng ndng do ferritin huyit thanh binh thudng, bdt thudng vi su dung sdt vd xdm nhap sdt van cd thi xay ra; cdc rdi loan ndy ed biiu biin gidng nhu thiiu mdu thiiu sat vi chdng cung co thi dan tdi thiiu mdu hdng cdu nhd.Phan Idn cdc binh nhan thiiu mdu do than vd suy gidm erythropoietin thudc loai nay.

Vi cd svr thay thi truyin mdu trudc ddy bdi chi dinh erythropoietin, cd thi kit hgp vdi dung sdt,ehuyin hda sdt d ede binh nhdn thdm phdm da thay ddi nhiiu. Trong khi trudc day thira sdt thudng xdy ra do hau qua eua viic truySn mdu thudng xuySn, ngay nay cdc rdi logn huy ddng sdt kSt hgp vdi du trii sat thda ddng Id diSm dac trvmg. Diiu ndy thi biin d dang miic bao hda transferrin thap phdi hgp vdi ndng do ferritin huyit thanh binh thudng hoac tang nhe. Do suy giam erythropoietin ciing cd thi dan tdi giam boat dgng sinh hdng eau,nhu cau sat thap ban vd vi vay su tdng hgp receptor transferrin binh thudng bode giam. Mat khdc niu su tgo hdng cdu dugc boat hda bdng chi dinh erythropoietin, cdc rdi loan huy ddng sdt tdn tai trudc dd biiu hiin dudi dgng ggi Id thiiu sdt chuc nang. Diiu nay duge phdt hiin bdng diiu hda tang tdng hgp receptor transferrin, giam miic bdo hda transferrin vd ed thi tdng protoporphyrin kem. Tuy nhiin, ndng do receptor transferrin hda tan ed thi ddng mdt vai trd Idn ban trong tuong lai nhu mgt chi diim true tiip eua nhu cdu sat.

(11)

S 6 2 - 2011 TAP CHI PHONG C H 6 N G BENH S 6 T RET VA CAC BENH KY SINH TRUNG 79

Roi loan

Thieu s i t

Roi loan phan bo s i t - binh man tfnh

T h cr a s i t

Tan huyet

Tao hong cSu khdng hidu qu3

ThCra sMt do thiy thudc (truyen mau

lap lai) NhiSm s i c

t 6 s l t

Ferritin

1

t

Transferrin

t

b t - 1

bt- i

i

S i t

b t - i

b t - t

bt- t

t

MLTC bao hoa transferrin

1

bt- i

b t - t

t

XN huy^t hpc

ThiSu mdu nhupc s^c hong cau nho

ThiSu mdu nhuac s i c hong cau binh thudng

Hong cJu ludi, vd dSfu hieu huyet tan

Hong c i u ludi, cdc XN l<hdc tujr thudc tsdnh

tidn phat Tuy thudc bdnh tidn

phdt, tdn thuong ca quan thCr phat Cdc dd'u hidu tSn thudng cd quan

thCJr phat

Bang 2: Cdc kit qua xet nghiim trong cdc rdi logn chuyin hda sdt

TdM

TAT

Sdt Id yiu td vi lugng cd vai trd sinh If quan trgng. Id nguySn td trung tam trong phdn tu hemoglobin vd myoglobin cung nhu nhiiu protein, enzym khdc.

Sat trong thuc an dugc hap thu d rudt non dudi dgng sat hai. Phan Idn tat ca sdt trong huyit thanh gdn vdi protein van chuyin Id transferrin. Thiiu sdt cd thi do chS do an udng khdng ddy du, kem hdp thu bode mdt sdt qud nhiiu thudng gap trong cdc binh nhiin giun mdc, md dan tdi thiiu mdu bdng cdu nhd nhugc sdc. Nong do sdt huyit thanh khdng phdi Id chi diim tin cgy cho tinh trgng sdt du trii eua ea thi, viic dinh lugng ning dg ferritin huyit thanh Id mdt xdt nghiim sinh hda tdt nhdt eua tinh trang du tru: sdt.

Sdt tu do rdt ddc vd nhiem ddc sdt, ddc biit d tri em, ed thi gdy chit ngudi. Thda sdt man tfnh xdy ra d binh nhiem sdc td sdt, mdt binh rdi logn do di truyin cd ddc diim tang hdp thu sdt qud miic trong thiic dn, dan tdi ldng dgng sdt trong rdt nhiiu nid cua ca thi nhu co tim, cdc tuyin ndi tiit nhu md gan. Ddc diim ldm sdng cdu nhiim sdc td sdt bao gdm ldng dgng sdc td da, xa gan, binh ca tim, suy chuc ndng ndi tiit. Binh duge diiu tri bdng cbfeb mdu thudng xuyin dk logi sdt khdi ca thi. Trong nhiem hemosiderin, sdt tfch tu do truyin mdu lap lai nhiiu lan dk diiu tri cdc thiiu mdu khd diiu tri;sdt thira ldng dgng trong ede t i bdo liin vdng ngi md. Diiu tri cdc trudng hgp ndy khdng thi diing biin phdp cbfeb mdu md phai diing cdc chdt tao phiic vgi sdt dk tang thai sdt ra khdi co thi.

(12)

TAI LIEU THAM KHAO

1. Manfred Wick.Iron metabolism and its disorders. In Ginical laboratary diagnostic, TH-Books Verlagsgesellschafl, firt edition, 1998: 268-273.

2. Marilin S.Weil,William M.Awas,JR. Iron and heme metabolism. In Textbook of biochemistry with clinical correlation, Willey-Liss, 3 rd edition,1992:1001-1023.

3. William J Marshall. Haemoproteins, porphyrins and iron. In Clinical chemistry, Mosby, third edition, 1995: 252-261.

Bien dich v^ tom tat TS. Cao Ba Loi

Vien S6tr6t KST-CT Tir C ^ bo hieu dfnh

CN. Tran Minh Tien Vien Sot r6t KST-CT TLT