Decreased circulating total IgG concentration

What it means

A reduction beneath the normal level of total immunoglobulin G (IgG) in the blood.

Reductions in total IgG levels in adolescents or adults may be classified as mild-moderate (300-600 mg/dL), significant (100-299 mg/dL), or profoundly reduced (less than 100 mg/dL). In adolescents and adults, a total immunoglobulin (IgG + IgM + IgA) level greater than 600 mg/dL, with confirmed normal antibody responses, probably excludes humoral deficiency. Total immunoglobulin levels of 400 to 600 mg/dL or IgG levels of 200 to 400 mg/dL may contain adequate amounts of antibody; this becomes less likely if total immunoglobulin levels are less than 400 mg/dL or serum IgG levels are less than 200 mg/dL.

Rare diseases that can present with this1

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Decreased circulating total IgG