Thyroid Hormones and Diagnostic Tests

Most sensitive first-line screening test for suspected thyroid abnormalities. Measures the amount of TSH in the blood.

If TSH is normal, no further testing is needed. If TSH is high, Free T4 is added. If TSH is low, Free T4 and T3 are added.

T4 is the prohormone, making up nearly 90% of thyroid hormone. T3 is the active form.

Unbound and metabolically active form of T4. Better indicator of thyroid status than Total T4.

Marker for well-differentiated follicular thyroid cancer. Also a protein precusor of thyroid hormone.

Marker for autoimmune thyroiditis and related diseases, directed against thyroglobulin.

Marker for autoimmune thyroiditis and related diseases. inflammatory and cytotoxic effects on thyroid follicle

Evaluating suspected medullary thyroid cancer, and monitoring for recurrence.

Used in hyperthyroidism cases, this scan measures the amount of radioactive iodine uptake by the thyroid gland.

Procedure to collect a tissue specimen to determine if the thyroid is benign in a test.

Glucocorticoids, Mineralocorticoids, Androgens, Progestogens, Estrogens

Alter carbohydrate metabolism (ex. Cortisol)

Influence fluid retention and loss.(Ex. Aldosterone)

Evaluation of anterior pituitary function; over or underproduction of cortisol (Cushing's, Addison's)

Suspicion for hyper- or hypofunctioning adrenal glands. Can be measured in serum, urine or saliva.

Cortisol High, ACTH Low, and caused by an adrenal tumor producing cortisol on its own.

Cortisol High, ACTH High, and caused by an ACTH-producing pituitary tumor or ectopic ACTH-producing tumor (lung cancer).

Cortisol Low, ACTH High, and caused by adrenal gland failure.

Cortisol Low, ACTH Low, and caused by hypopituitarism.

Evaluation of cause of adrenal insufficiency; assess adrenal gland response to ACTH.

Diagnosing Cushing syndrome and distinguishing its cause.

Evaluation and monitoring of adrenal hyperplasia and adrenal tumors.

Used to assist in diagnosis of diabetes mellitus; evaluates patients with hypoglycemia.

Indication that kidneys are unable to reabsorb gucose.

Part of routine urinalysis and diabetes control. End products of fatty acid breakdown.

Diagnosis of glucagonoma; evaluation of diabetes and pancreatic function.

Diagnose insulinoma; evaluate abnormal lipid and carbohydrate metabolism, and fasting hypoglycemia.

Evaluation of insulin resistance, identification of type 1 diabetes; monitoring pancreatic islet cell transplantation.

Insulin autoantibody.

Islet cell antibody. Autoimmune destruction of cells.