Thyroid Stimulating Hormone (TSH) Lab Values

Objective: Determine the significance and clinical use of  Thyroid Stimulating Hormone in clinical practice   Lab Test Name: Thyroid Stimulating Hormone   Description: Thyroid Stimulating Hormone (TSH) is released from the anterior pituitary in response to low levels of thyroid hormone.  TSH stimulates the thyroid gland to release thyroid hormones Triiodothyronine (T3)  Thyroxine (T4) T3 and T4 have an inverse relationship with TSH   Indications: Aids to diagnose: Hyperthyroidism Hypothyroidism Anterior pituitary function Monitor:  Thyroid replacement therapy   Normal Therapeutic Values: Normal –  2-10 mU/L Collection:  Plasma separator tube   What would cause increased levels? TSH levels increase in the following conditions: Hypothyroidism Thyroidectomy Thyroid dysfunction Thyroiditis Thyroid Agenesis Large doses of iodine Pituitary TSH-secreting tumor   What would cause decreased levels? Recall the inverse relationship between TSH and T3/T4 labs, and how the negative feedback loop works with these hormones. TSH levels decrease in the following conditions: Anterior pituitary hypofunction- If the pituitary isn’t secreting TSH, the level will be low. Hyperthyroidism- If there is a large amount of thyroid hormone circulating, the feedback system relays the info upstream and less TSH is released.