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Chlamydia IgG in men: antibodies against chlamydia and what the result says

When bacteria enter the body, the immune system makes proteins that fight them, antibodies. According to MedlinePlus, IgG antibodies are aimed at one germ and are remembered even after an infection has cleared, and chlamydia IgG are the IgG antibodies against chlamydia bacteria.

According to the RIVM, chlamydia runs without symptoms in half of cases in men too, and a positive antibody test can fit an earlier or a current infection. Only a blood test shows whether the body has made chlamydia antibodies.

Star-SHL and Diagnostiek voor U give 'negative' as the expected result for chlamydia IgG, without a unit.

Doctor's Assessment Included

The chlamydia IgG test looks in the blood for antibodies against chlamydia, which the body makes after contact with the bacterium. Normally the result is negative.

  • A chlamydia antibody test cannot tell an earlier infection from one that is still active; for a current infection, a PCR test on urine or a swab is the usual test.
  • A negative chlamydia antibody test does not rule out an infection: not everyone makes measurable antibodies, and the test is less sensitive than a PCR test.
  • In a fertility work-up, a positive chlamydia antibody test (CAT) counts as a risk factor for damage to the fallopian tubes.

Reference Ranges

Expected result Negative

Reference ranges may vary between laboratories. When you order a test, a BIG-registered doctor assesses your personal results in context. For treatment decisions, discuss your results with your GP.

Check your own value

Chlamydia IgG: what this test measures

The chlamydia IgG test determines in the serum whether IgG antibodies against chlamydia are present, and the result is positive or negative, without a unit. According to the RIVM, a positive chlamydia IgG result can also come from antibodies against another chlamydia species, because antibodies against the different species cross-react a great deal.

Chlamydia IgG: why this value matters

According to the RIVM, a chlamydia infection that rises in men is associated with a chronic inflammation of the prostate and/or the epididymis in 1 to 4% of cases. According to the RIVM, the chance of infertility in men after chlamydia is disputed, although a temporarily reduced sperm quality has been found during an infection.

In rare cases, chlamydia can lead to SARA according to the RIVM, a reactive joint inflammation after an STI, with inflammation such as of the joints, eyes or tendons.

Chlamydia IgG: how the blood test works

Referral
No GP referral needed. After the order we arrange the referral through ZorgDomein, within one business day; orders after 17:00 or at the weekend start on the next business day. ZorgDomein emails a barcode, and that barcode is what the draw site needs.
The draw
A blood draw from a vein in the arm, at a partner laboratory's draw site. No home kit, no finger prick.
Which test
IVF Partner Screening (Men) · €325,-
Where
650+ draw sites run by independent laboratories across the Netherlands. Draw sites

Chlamydia IgG: when is testing worthwhile?

According to the RIVM, a chlamydia antibody test makes no distinction between a current and a cleared infection. With chlamydia symptoms in men, such as burning urination, discharge or pain in the scrotum, a NAAT searches for genetic material of the bacterium, with a high sensitivity and specificity according to the RIVM.

Chlamydia IgG: symptoms of a high or low value

Low Levels

A negative chlamydia IgG result is the expected result at Star-SHL and Diagnostiek voor U. According to the RIVM, a NAAT on urine or a swab detects a current chlamydia infection more sensitively and more accurately than an antibody test in the blood.

High Levels

With a positive chlamydia IgG result, IgG antibodies against chlamydia were found in the serum, which can come from an earlier or current infection or from another chlamydia species. According to the RIVM, symptoms in men with chlamydia are burning urination, watery to pus-like discharge especially in the morning, and sometimes pain in the scrotum from an inflamed epididymis.

Chlamydia IgG: causes of a low or high value

What raises the value

  • Earlier chlamydia infection

    Chlamydia antibodies can come from an infection that has already cleared or been treated.

  • Current, untreated infection

    A chlamydia infection that is still present can also give a positive result; the chlamydia blood test cannot tell a current infection from an earlier one.

  • Other chlamydia species

    Depending on the test, antibodies against other chlamydia species can cross-react, for example antibodies against the airway bacterium Chlamydia pneumoniae; the RIVM notes much cross-reaction between chlamydia species.

Chlamydia IgG: lifestyle and this value

With symptoms when urinating or in the scrotum after a positive chlamydia IgG result, the GP is the one to see. According to the RIVM, a NAAT, on urine or a swab, is the usual test for a current chlamydia infection. With a confirmed current chlamydia infection, the RIVM calls informing sexual partners a necessary part of sexual health care.

Chlamydia IgG: frequently asked questions

Does a man with chlamydia always have symptoms?

No, a man with chlamydia does not always have symptoms: according to the RIVM, a chlamydia infection in men runs without symptoms in half of cases. According to the RIVM, men with chlamydia do have symptoms more often than women with chlamydia.

Can chlamydia affect male fertility?

The effect of chlamydia on male fertility is not clear: according to the RIVM, the chance of infertility in men after chlamydia is disputed. During a chlamydia infection, a temporarily reduced sperm quality has been found.

Can chlamydia be tested with urine?

Yes, according to the RIVM chlamydia can be detected with a NAAT on urine, a test with a high sensitivity and specificity in urine and in swabs. According to the RIVM, a chlamydia antibody test in the blood is less sensitive.

Chlamydia IgG: sources

  1. RIVM, LCI-richtlijn Chlamydia trachomatis en lymphogranuloma venereum, vastgesteld 25 juni 2024, geraadpleegd 2026-10-05 (retrieved 2026) lci.rivm.nl
  2. RIVM, LCI-richtlijn Chlamydia pneumoniae, hoofdstuk Diagnostiek vastgesteld 5 april 2019, geraadpleegd 2026-10-05 (retrieved 2026) lci.rivm.nl

Test Products

This marker is included in the following test panels.

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Chlamydia IgG

€49,-