Thread tentang Hepatitis B serology untuk medical students & house officers.

#tweetorial #FOAMed #hepatitisB

Dr strange cakap,

okay jom

40 yo gentleman, came fever, malaise, arthralgia, yellowish discoloration eyes. He admits of multiple sexual partner. Liver enzymes elevated. U wanna screen for hepatitis, u took anti-Hcv for hep C, for Hep B what will u order?

being the excellent HO u are, u ordered serum HBsAg (hepatitis B surface antigen) for hepatitis B screening. tapi pernah tak tanya kenapa kita ambil HBsAg, bukan HBeAg ke, HBcAg ke?

"OoooOOoo, HBsAg tu maksud dia surface antigen ke boss?"

pearls untuk hepatitis

Hep B satu2nya DNA virus, yg lain semua RNA
Hep A spread thru feco-oral, shellfish
Hep B, C thru direct contact blood product
hep C associated with HCC
Hep B usually has Hep D co-infection

lets focus on Hepatitis B:

fokus gambar ni pertama virus-
hepatits B ada dua lapisan.
lapisan luar atau kulit dia (envelope), atas kulit ada beberapa protein S, M, L. macam saiz baju.
protein2 tu ialah antigen. Sbb dia duduk di surface, kita panggil Hep B surface Ag (HBsAg).

sambung-

lepas tu dalam envelope tu ada isi, Hep B core, yg warna hijau diamond.
di Hep B core pun ada protein yg act as Ag. Jadi kita panggil protein tu Hep B core Antigen (HBcAg).

ruang antara envelope dan core, ada protein terapung2, yg hijau macam peluru, kita panggil Hep B E-antigen (HBeAg)

okay tak lagi ni?

so untuk recap, Hep B ada 3 antigen
HBsAg di surface of Hep B, atau envelope
HBcAg di isi, atau core
HBeAg antara S dan C

bila ada HepB infection,

immune response pun hasilkan antibody kepada Ag tu lah;

1. anti-HBs
2. anti-HBc
3. anti-HBe

sebab HBsAg ni duduk di HepB virus surface, kalau HBsAg ni ada dalam darah maksudnya pt tu ada Hep B infection. Bad news!

Lagi banyak HBsAg dalam darah, lagi banyak symptoms.

Jadi badan akan hasilkan anti-HBs untuk lawan. tapi ambil masa nak hasilkan anti-HBs.

tapi HBsAg cuma cakap pt ada virus dalam badan, tapi tak tahu pt tu dalam chronic, carrier, cured, infective state?

sebab vaccine Hep B, kita pun cucuk HBsAg dalam badan untuk stimulate immune response to produce anti-HBs (hello medical students, primary secondary response!)

HBeAg!

ingat HBeAg ni terletak antara surface dan core. Jadi bila Hep B virus replicate, apa jadi?

HBeAg ni terkeluar dan detected dlm serum.

Jadi HBeAg ni ialah marker for viral replications. Kalau dia ada, maksudnya pt tu infective. Virus tengah membiak dalam badan dia.

HBcAg, core antigen ni tak circulate dalam darah. Tapi, antibody terhadap core antigen, anti-HBc ni kita boleh test.

IgM-HBc dan IgG-HBc.

dia boleh bagitau kita patient ni acute (IgM-HBc) atau chronic (IgG-HBc) infection.

kalau ada HepB infection,

HBsAg akan banyak dalam badan. sebab HBsAg ni yg produce symptoms (ingat S, symptoms).

badan akan try produce anti-HBs, tapi untuk produce anti-HBs ambil masa lama.

jadi bdn hasilkan IgM-HBc (antibody M against HepB core) dulu. Kemudian IgG-HBc.

recap balik:

HBsAg
kalau positif = infection (or vaccination). ada virus HepB dalam badan (usually detected 1-6 months post exposure).
anti-HBs present, maksudnya badan dah buat antibody terhadap HepB virus. Cured or vaccinated.
HBsAg persist more than 6 months = carrier.

HBeAg
kalau positif = infective state
anti-HBe pun sama. diorang ialah marker for viral replication, jadi infectivity

HbcAg
HepB core tak circulate dalam darah
anti towards core Ag yg circulate, kita guna untuk tengok acute (IgM-HBcAg) atau chronic/past infection (IgG-HBcAg).

body will only produce anti-HBc if pt was infected. kalau vaccinated, will not have anti-HBc, but anti-HBs only!

so faham dah kenapa kalau screening kita ambil HBsAg?

sebab nak tengok ada HepB virus ke tak dalam badan, based on surface Antigen. kalau ada, baru kita proceed dengan yg lain.

cc: @zerotofinals

jom test,

HbsAg +
HBeAg +
anti-HBs negative
anti-HBc +

jawapan dia active infection.

okay Question 2,

HBsAg negative
HBeAg negative
anti-HBs +
anti-HBc +

jawapan dia past infection. Sebab immunity dia dapat not from vaccination, dia ada anti-HBc. Vaccine didnt confer immunity against core Ag, only surface Ag.

Q3,

HBsAg +
HBeAg +
anti-HBs negative
anti-HBc +
anti-HBe negative

Mrcp part 1. jawapan dia infected, high infectivity.

sebab kalau HBeAg positive, tapi badan belum sempat produce anti-HBe, rate of infection lagi tinggi berbanding yang dah ada anti-HBe dalam badan.

last Question, mrcp part 1.

sex worker came for screening, results as follow:

HBs-Ag negative
anti-Hbs +
anti-HBc +
HBeAg negative
anti-HBe +

jawapan dia immunity post infection.

chronic dan acute infection salah sebab HBsAg negative.

post vaccination salah sebab, vaccine tak ada HBcAg, jadi bdn akan hasilkan anti-HBs sahaja.

Thank you!