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Thyroid and Parathyroid

Terms in this set (22)

What cells are responsible for the production of calcitonin in the thyroid?
Parafollicular Cells or C cells
What does calcitonin do?

What does PTH do?
-Reduces Ca+ levels in the blood

-Increases Ca+ levels in the blood (bone resorption)
What does T3 (triiodothyronine) and T4 (thyroxine) do?
-Increase O2 consumption
-Increase thermogenesis
-Increase expression of LDL receptor (hypothyroidism may cause hyperlipidemia)
In both the hypothalamus and pituitary, T3 or T4 is primarily responsible for the inhibition of TRH (thyrotropin-RH) and TSH secretion?
T3
Since the thyroid is capable of auto regulation, independent of TSH, What can inhibit synthesis and secretion of thyroid hormones (2) ?
What can stimulate Thyroid production?
-iodine excess or Glucocorticoids

-Epinephrine and human chorionic gonadotrophin hormones (pregnancy)
A single level of what...permits an accurate classification of thyroid status?

Why?
TSH, (T3 and T4 confirm significance of abnormal TSH findings)

-Because very small changes in serum free T4 concentrations induce very large reciprocal changes in TSH concentrations
How much of serum T4 is bound?

How can serum T4 assays be measured?
-Nearly all 99.97 %, to TBG (thyroxine binding globulin) , TBPA (transthyretin ), or albumin.

-Both bound and unbound (free) T4
How is T3 bound ?

What are the lab ranges like for T3 and T4?
-Less tightly to TBP and TBPA but more tightly to albumin than T4

-Normal ranges vary among laboratories but T3 is more variable than T4
What ways are thyroid imaging done? and what can these show?
-Ultrasound: size, texture, nodules (solid or simple or partially cystic)

-CT & MRI: Tracheal deviation or narrowing, and extension of thyroid into the mediastinum

-Radionuclide Scans: "cold" =hypofunctional (more risk of malignancy)
"hot"= hyperfunctional
What is the first approach after finding a thyroid nodule on a patient?
-Check TSH
If decreased, normal, or increased TSH, what should you do next?
-if decreased; check thyroid scan and if toxic adenoma then need radioidoidne or surgery

-if normal: Check if diameter > 1.0-1.5 cm, if so then fine-needle aspiration biopsy

-if increased: Check antithyroid ab titers, if none present then treat w/ levothyroxine
What if the nodule is benign?
-only consider surgery if it becomes an issue
What are the 4 types of malignant thyroid nodules?
-Papillary thyroid carcinoma (MOST COMMON)
-Medullary Thyroid carcinoma
-Thyroid lymphoma
-Anaplastic Thyroid Carcinoma( *rarest w/ worst Px)
If the FNA biopsy comes back malignant for Papillary thyroid carcinoma or medullary thyroid carcinoma what should you do ?
Surgery
If the FNA biopsy comes back malignant for Thyroid Lymphoma of Anaplastic Thyroid Carcinoma, what should you do ?
chemo and radiation
What if the FNA biopsy result is non diagnostic?
Ultrasound-guided FNA biopsy
What if the FNA biopsy is intermediate?
surgery or thyroid scan
What 2 signs are common in hypoparathyroidism?
-Chvostek's sign- abnormal reaction to stimulation of facial nerve

-Trousseaus's sign-Bp cuff around arm for 3 min. to occlude brachial artery and the absence of blood flow with hypocalcemia will cause the "*hand of the obstetrician"
What is the significance in the lab serum albumin for hypoparathyroidism?
-BC hypoalbuminemia causes a drop in total CA++
What is the most common cause of hyperparathyroidism
Parathyroid adenoma
Who is hypoparathyroidism most likely to be seen in ?
Postmenopausal women , might be a genetic link
What are the S/S of hyperparathyroidism ?
*"Bones, stones, abdominal groans, psychic moans w/ fatigue overtones"
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