Free T4 Thyroxine Dialysis

This test measures levels of T4 or Thyroxine in the blood. T4 is one of the primary hormones produced by the Thyroid gland which helps to control a number of metabolic functions. Most T4 is bound to proteins and the small portion of unbound T4 or Free T4 is biologically active and able to be used by the body. This test measures Free T4 levels using the Equilibrium Dialysis and Chromatography/Mass Spectrometry methodologies. Measuring T4 through this method may be more accurate than a standard T4 test in some cases. Certain conditions such as Thyroxine Binding Globulin Deficiency, pregnancy, hormone therapy, taking oral contraceptives, taking antipsychotic medications and other illnesses can cause inaccuracies in a regular Free T4 blood test. This can result in failure to diagnose conditions such as hyperthyroidism and hypothyroidism. In these cases, a Free T4 by Dialysis test may be a more effective option.

The Free T4 Dialysis test is typically ordered when someone has symptoms of a thyroid disorder but has other conditions which may render standard testing methods ineffective. A Dialysis test may be used as a follow up to a regular Free T4 blood test when a person has thyroid disorder symptoms but their test results are normal.

Turnaround for this test is typically 8-10 business days.