Importance of tsh analysis
TSH testing is used to evaluate thyroid gland function as it pertains to the primary cause of hypothyroidism.
It is also used to check for congenital disorders, tumors, cancer, and inflammation.
Normal values
| Age | Conventional Units | SI Units |
| Neonate-3 days | <40 micro-international units/mL | < 40 milli-international units/L |
| 2 weeks-5 months | 1.7-9.1 micro-international units/mL | 1.7-9.1 milli-international units/L |
| 6 months-1 year | 0.7-6.4 micro-international units/mL | 0.7-6.4 milli-international units/L |
| 2 years-19 years | 0.5-4.5 micro-international units/mL | 0.5-4.5 milli-international units/L |
| 20 years + | 0.4-4.2 micro-international units/mL | 0.4-4.2 milli-international units/L |
Abnormal values and indications
An increase in thyroid hormone levels activates the feedback loop to decrease production of TSH.
Excess thyroid hormone replacement.
Grave’s disease
Primary hyperthyroidism.
Secondary hyperthyroidism r/t pituitary involvement, decreasing production of TSH.
Tertiary hypothyroidism r/t hypothalamic involvement, decreasing production of TSH.
A decrease in thyroid hormone levels activates the feed- back loop to increase production of TSH.
Congenital hypothyroidism in the neonate (filter paper test).
Ectopic TSH-producing tumors (lungs and breasts).
Primary hypothyroidism related to dysfunction of the thyroid gland.
Secondary hypothyroidism r/t pituitary hyperactivity.
Thyroid hormone resistance.
Hashimoto autoimmune disease (thyroiditis).
Patient care and teaching
Before
Explain that there may be some discomfort during the venipuncture.
Explain the reason for the test and answer any questions to alleviate anxiety.
Determine if any medications are being taken that could potentially alter test results (e.g: amiodarone, iodides, lithium, corticosteroids, t3, t4, and certain multivitamins).
No fasting is required.
During
Watch for vasovagal responses to venipuncture. Patients prone to syncope are at risk for falling and injury.
After
Inform the patient of potential side effects such as bruising, phlebitis, and cellulitis.
Discuss expected outcomes including maintenance of a healthy weight, agreeing to a weight reduction program to achieve a healthy BMI, and having an absence of bradycardia with a pulse greater than 60 bpm.
Nursing diagnoses
Risk for falls
Risk for decrease cardiac output
Fatigue
Risk for impaired tissue integrity
Knowledge deficit
Follow-up testing
Related tests include adrenocorticotropin hormone, albumin, antibodies antithyroglobulin, biopsy thyroid, copper, follicle-stimulating hormone, growth hormone, luteinizing hormone, newborn screening, PTH, protein total, RAIU, thyroglobulin, TSI, TBII, thyroid scan, T4, free T4, T3, free T3, and US thyroid.
Ethical considerations
One ethical issue to take into consideration when it comes to TSH testing is over-testing, which has become more and more commonplace in our health-conscious society. It is important to perform diagnostic testing only when it is deemed truly necessary.
As is the case with all testing, autonomy, consent, and confidentiality are crucial when it comes to providing quality patient care. Ensuring privacy and providing adequate information in order for patients to make informed decisions about their care is vital.
Sources
Van Leeuwen, A. M., & Bladh, M. L. (2016). Textbook of laboratory and diagnostic testing: Practical application at the bedside. Philadelphia, PA: F. A. Davis Company.