Endocrine Labs Flashcards
Signs & Symptoms of Hypothyroidism
fatigue or sluggishness weight gain cold intolerance dry skin, brittle hair constipation, slows digestion slows heart and respiration menstrual irregularities
Signs & Symptoms of Hyperthyroidism
anxiety, irritable, difficulty sleeping weakness in arms and legs tremors feels hot, perspires a lot weight loss frequent bowel movements irregular heartbeat
Can you order a TSH if the patient presents with one symptom alone?
Yes
Name the 5 thyroid function tests
TSH Total T4 Total T3 Free T4 Free T3
Secretion of T4 and T3 by the thyroid gland is regulated by TSH from the?
pituitary
TSH levels are controlled through…
a negative feedback system
Describe the negative feedback system of TSH
Starts with an abnormal serum T4 or T3 level, which triggers thyrotropin-releasing hormone (TRH) in the hypothalamus to trigger the release of TSH
What is the normal value range for TSH?
0.4-4.2 mU/L for adults
What is the best test to assess thyroid function?
TSH
If TSH is normal, does this allow for further testing?
No
An elevated TSH points to?
Hypothyroidism
A low TSH points to?
Hyperthyroidism
An elevated TSH can be followed with what test?
Free T4 (to determine the degree of hypothyroidism)
A low TSH can be followed with what test?
Free T4 and possibly a Free T3 (to determine the degree of hyperthyroidism)
What test is used to monitor therapy in patients with hypothyroidism?
TSH test
Individuals with hypothyroidism take what thyroid medication?
levothyroxine
If a patient taking levothyroxine has a high TSH, they are still in the “hypo” range and need to do what to their medication dose?
increase it
If a patient taking levothyroxine has a low TSH, they are still in the “hyper” range and need to do what to their medication dose?
Reduce it
After administering levothyroxine to a patient when should they come back in for a check-up?
4-6 weeks to monitor TSH levels
What could be reasons for an abnormally elevated TSH level?
Primary hypothyroidism
Medication interactions
Certain tumors
What could be reasons for an abnormally low TSH level?
Primary hyperthyroidism
Euthyroid sick disease
Thyroid nodules or goiter
These labs measure both the amount of T4 or T3 that is bound to proteins in the blood and what is not bound
Total T4 and Total T3
These labs are not commonly used in primary care
Total T4 and Total T3
These labs increase in hyperthyroidism and decrease in hypothyroidism
Total T4 and Total T3