The serum iron test measures the amount of iron in your blood. The total iron-binding capacity (TIBC) test looks at how well the iron moves through your body.

Thyroxine-binding globulin (TBG) is a globulin that binds thyroid hormones in circulation. It is one of three transport proteins (along with transthyretin and serum albumin) responsible for carrying the thyroid hormones thyroxine (T4) and triiodothyronine (T3) in the bloodstream. Of these three proteins, TBG has the highest affinity for T4 and T3 but is present in the lowest concentration. Despite its low concentration, TBG carries the majority of T4 in the blood plasma.

NOTE: This test can only be purchased by men with suspect PSA over 4 mg/dL.  Free PSA will not be provided for PSA under 4 ng/mL.

PSA circulates through the body in two ways; bound to other proteins or by itself. Unbound PSA is called free PSA. A free-PSA test will measure the percentage of unbound PSA while a PSA test is used to measure the total of free and bound PSA in the blood. The free PSA is a defective variant of normal PSA that can no longer bind to other proteins and so circulates in the blood in the free form. Although the reason why this is the case is poorly understood - patients with prostate cancer may have lower free PSA levels than those with a benign prostate condition.

This test measures the amount of dihydrotestosterone (DHT) in the blood.  Low DHT has been associated with low libido and high DHT has been linked to acne, hair loss and benign prostatic inflammation in a minority of men.

The thyroid stimulating hormone (TSH) is produced and secreted by the pituitary gland and stimulates the thyroid to produce T3 and T4. When TSH is elevated, low thyroid function may be indicated. If TSH is low it is indicative of high thyroid function. A study found that TSH was suppressed in all subjects after food, so fasting may be suggested although it is not reqired by Quest. Free T4 and Free T4 values did not change significantly after eating.

Immunoglobulin A (IgA) is a crucial antibody in the immune system, predominantly found in mucous membranes of the respiratory and gastrointestinal tracts. It helps protect against infections by neutralizing pathogens before they can cause harm. Testing IgA levels can provide insights into immune health, indicating potential issues such as chronic infections, autoimmune diseases, or immunodeficiency disorders. Elevated or decreased IgA levels can signal various health conditions, making this test valuable for diagnosing and managing immune-related issues. For those experiencing frequent infections or gastrointestinal issues, an IgA test can be an essential diagnostic tool.