ASO

Japanese: ASO

Reference value

250 credits or less

What is ASO?

Produced by Streptococcus pyogenes β beta Hemolytic toxins (streptolysin O Oh = SLO) antibodies.

When streptococci invade the body and release toxins (SLO), ASOs appear and fight.

Streptococcus attacks not only the tonsils but also the glomeruli of the kidneys.

This is a test to check whether or not you are infected with streptococcus. Since ASO fluctuates even in healthy people, we will repeat the test unless the result is clearly positive.

High levels during tonsillitis

Tonsils Tonsil The area becomes red and swollen, and there is a fever and throat Throat Pain and White moss Pact Tonsillitis, which is a common condition, is caused by a bacterial infection, one of which is Streptococcus pyogenes (strep).

When this bacterium infects the body, it produces a toxin, and the body produces antibodies (ASO) against this toxin in an attempt to eliminate the bacterium, which is an antigen. Therefore, by measuring this antibody and finding a positive result, it can be determined that the change is due to a streptococcal infection.

High levels in acute glomerulonephritis

Streptococcus can also cause acute glomerulonephritis. If a patient develops tonsillitis and has a high fever for several days, followed by lower back pain and hematuria, acute glomerulonephritis may be suspected. If acute glomerulonephritis occurs, blood pressure rises, urine tests show positive for proteinuria (see reference), and urine sediment Chinsa (→ Reference) will cause red blood cell positivity, and blood tests will show elevated levels of urea nitrogen (→ Reference) and creatinine (→ Reference). Acute glomerulonephritis requires early hospitalization for treatment.

In acute glomerulonephritis, it is not the streptococci that directly damage the glomeruli; rather, a complex formed by the combination of ASO and bacterial components damages the glomeruli.

In addition, streptococci can also cause rheumatic fever, which is complicated by arthritis and valvular heart disease.

Repeat measurement unless clearly positive

It is measured using serum. ASO fluctuates even in healthy people, and unless it is clearly positive, it should be remeasured at intervals of at least two weeks, and if there is a change of two or more levels, it is considered positive.

Among the streptococci, streptolysin O Oh There are also bacteria that produce toxins other than those listed above, and in these cases, even if the patient is infected with streptococci, the ASO test will be negative, so another measurement method (antistreptokinase, ASK) is used to check for the presence or absence of streptococcal infection.

If positive and symptomatic, further testing is required.

Even if you are infected with streptococcus, your ASO will be negative for 2 weeks, then it will start to rise after 2 weeks, reach a high level in the short term (4-6 weeks), and then gradually decrease. Antibiotic treatment can suppress the rise in antibody titers.

If there are no symptoms and the ASO is positive, it indicates a previous infection with streptococcus. If symptoms (fever, joint pain, palpitations, hematuria, etc.) are present, blood and urine tests will be performed to identify the site of streptococcus infection and any complications.

The main diseases suspected are

◆ High levels → tonsillitis, rheumatic fever, acute glomerulonephritis, scarlet fever Heat , purpura, etc.

◆ Low level → immunodeficiency syndrome

The general term used by doctors is "ASO", an abbreviation of antistreptolysin O. It is derived from AS(L)O. It is also called "Asuro".

Source: Hoken "4th Edition: A book that explains the tests you will receive at the hospital" Information about the 4th Edition: A book that explains the tests you will receive at the hospital

Japanese:

基準値

250単位以下

ASO とは

　溶血性連鎖球菌によってつくられるβベータ溶血毒素（ストレプトリジンOオー＝SLO）に対する抗体のこと。

溶連菌が体内に侵入し、毒素（SLO）を振り巻くとASO が出現し、戦う

溶連菌は扁桃だけでなく、腎臓の糸球体も襲う

溶連菌に感染しているか否かを調べる検査です。ASOは健康な人でも変動があるため、明らかな陽性以外は再度測定を行います。

扁桃炎のときに高値に

　扁桃へんとうが赤くはれ、発熱と喉のどの痛みや白苔はくたいを認める扁桃炎は、細菌が感染して発症しますが、その原因菌のひとつに溶血性連鎖球菌（溶連菌）があります。

　この菌は、感染すると毒素をつくり、生体は、この毒素に対して抗体（ASO）をつくり、抗原であるこの菌を排除しようとします。したがって、この抗体を測り、陽性になれば溶連菌に感染した変化であることが判定できるわけです。

急性糸球体腎炎でも高値に

　溶連菌はまた、急性糸球体腎炎をおこします。扁桃炎をおこしたとき、数日高熱が続き、その後、腰痛、血尿が現れると、急性糸球体腎炎の合併が疑われます。急性糸球体腎炎の合併では血圧が上昇し、尿検査では尿蛋白（→参照）が陽性、尿沈渣ちんさ（→参照）で赤血球陽性になり、血液検査では尿素窒素（→参照）やクレアチニン（→参照）が上昇します。急性糸球体腎炎は、早期の入院加療が必要になります。

　なお、急性糸球体腎炎は溶連菌が直接、糸球体を障害するのではなく、ASOと菌体成分が結合した複合体が糸球体を障害します。

　その他、溶連菌は、関節炎や心臓弁膜症を合併するリウマチ熱の原因にもなります。

明らかな陽性以外は再測定

　血清を用いて測定します。ASOは健康な人でも変動があり、明らかな陽性の場合以外は2週間以上の間隔で再測定し、2段階以上の変動があれば陽性と判断します。

　溶連菌の中には、ストレプトリジンOオー以外の毒素をつくる菌もいて、この場合は溶連菌に感染していてもASOは陰性になるため、ほかの測定法（抗ストレプトキナーゼ、ASK）を行い、溶連菌感染の有無を調べます。

陽性で症状を伴えば、くわしく検査

　溶連菌に感染しても、ASOは2週間は陰性で、2週間後から上昇し始めて短期（4～6週）で高値になり、その後、次第に低下していきます。抗菌薬治療で、抗体価の上昇は抑えられます。

　症状がなく、ASOが陽性の場合は以前に溶連菌に感染したことを示します。症状（発熱や関節痛、動悸、血尿など）を伴う場合は、血液や尿などの検査を行い、溶連菌感染の部位、合併を明らかにします。

疑われるおもな病気などは

◆高値→扁桃炎、リウマチ熱、急性糸球体腎炎、猩紅熱しょうこうねつ、血管性紫斑病など

◆低値→免疫不全症候群

医師が使う一般用語
「エーエスオー」＝antistreptolysin O（抗ストレプトリジンO）の略。AS（L）Oから。「アスロ」とも