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ACUTE CARr HANDBOO .... FOR PHY,KAI Tl-lfRAPI,'P;

Table 11-2. Thyroid Hormone Tests

Hormone

Test Description

Normal Value

Serum thyroxine

Radioimmunoassay

4-12 �gldl

(RIA) measuremelll.

Serum triiodo

RIA measuremcnt.

40-204 ngldl

thyronine

Free thyroxine indcx

Direct RIA measurc

Direct' 0.8-2.7 nglml

ment or indirect

Indirec" 4.6- 1 1.2 ng/ml

calculated measurememo

Thyroid-stimulating

Radioisotope and

0.4-8.9 pU/ml

hormone (TSH)

chemical bhelmg

measurcment.

Thyrotropin-releasing

Intravenous admll1is

Normal rise In men and

hormone (TRH)

tration of TRH to

womcn iii 6 pU/ml

TRH augments the

patients.

above basellllc TSH

function of TSII

The expected

levels.

in patients with

response is a rise in

Normal rise in men older

hypothyroidism.

TSH levels.

than 40 years IS 2 �U/

Only performed 111

rut above basehne.

difficult diagnos

Hypothyroidism is mdiric cases.

cated by Increased

response to TRH.

Hypcrrhyroidism is indicated hy no response to

TRH.

Sources: Data frolll WM Burch (cd). Endocrinology for Ihe House Officer (2nd cd).

Baltimore: Williams & Wilkins, 1988; 1: JV Corbett (cd). LaboratOry Te:.t!. and Dla{tnosric Procedures with Nursing Diagnoses (5th cd). Upper Saddle River. NJ: Prentice Hall Health. 2000;409-413; LM Malarke)', ME McMorrow (cds). Nur\C's 1\tanual of

Laborarory Tests and Diagnostic Procedures. ))hilJ.ddphia: Saunders, 2000;604-612.

and RA Sacher, RA MtPherson, J1\1 Campos (eds), Widman's Clinical 1mcrprctaU0l1 of

Laboratory Tcsrs (II rh cd). Philadelphia: FA Davis, 2000;786-791.

they are metabolically active by themselves. Thyroxine-binding globulin (TBG) is the major thyroid transport protein. Serum levels of T4

and T3 are usually measured by RIA. Table 11-2 describes the tests

used to measure thyroid hormones, and Table I 1 -3 summarizes other

tests used to measure thyroid function.

ENDOCRINE. SYSTEM

655

Table 11-3. Thyroid Function Tests

Test

Description

Triiodothyronine

RT3U indirectly measures rhe number of unoccupied

resin uptake

protein binding sites for serum thyroxine (T4) and

(RT3U)

serum triiodothyronine (T3) by using radioisotopes.

RT3U qualifies levels of bound versus unbound T4 and

T3. Thyroid hormone uptake is high with hyperthyroidism and low wirh hypothyroidism.

Thyroidal 24·hr

Used to determine mecabolic activity of the thyroid

radioactive

gland. Radioactive iodine is administered, and the periodine uptake

centage of tOtal administered radioactive iodine taken

lip by the thyroid in 24 hrs is then calculated.

Normal radioactive iodine uptake is 5-30%.

Hypothyroidism results in reduced uptake.

Thyroid imaging

Intravenous administration of radionuclides allows

or scan

imaging or scanning of particular areas of the thyroid gland.

Increased or decreased uptake of the radionuclide can

help diagnose dysfunction.

Ultrasound

Nodules of rhe thyroid gland that are palpable or suspected may be delineated as cystic or solid lesions by

ultrasound.

Needle biopsy

Fine needle aspiration of thyroid cells may help diagno�e

a suspected neoplasm.

Sources: Data from WM Burch (ed). Endocrinology for the House Officer (2nd ed).

Baltimore: Williams & Wilkins, 1988;1; M Harrog ted). Endocrinology. Oxford, UK:

Blackwell Sciemific, 1987;25; ;:Inc! RA Sacher, RA McPherson,JM Campos (eds). Widman's Clinic

2000;786-793.

Clinical Tip

• Low levels of thyroid hormones T3 or T4 may result in

weakness, muscle aching, and stiffness. Based on this

information, the physical therapist may decide to alter

treatment parameters by decreasing the treatment intensity

to optimize activity tolerance, minimize patient discomfort, or both.

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Aa..rrE CARE HANDBOOK FOR PHYSICAL TlIERAI'ISTS

• Patients may be on bed rest or precautions after radionuclide studies. The physical therapist should refer to the physician's orders after testing to clarify the patient's

mobility status.

Thyroid Disorders

Disorders of the thyroid gland result from a variety of causes and can

be classified as hyper- or hypothyroidism.

Hyperthyroidism

Hyperthyroidism, or thyrotoxicosis, is characterized by excessive

sympathomimetic and catabolic activity resulting from overexposure

of tissues ro thyroid hormones. The most common causes of hyperthyroidism are outlined in Table 11-4.

General signs and symptOms of hyperthyroidism include rhe

foIlO\vingl,6:

• Nervousness, irritation, and emotional lability

• Fatigue, weakness, and weight loss despite normal or increased

appetite

• Palpitations, atrial fibrillation (common above the age of 60

years), and tachycardia (heart rate of more than 90 beats per

minute at rest)

• Increased perspiration, moist and warm hands, and smooth and

vel very skin

• Heat lmolerance

• Diarrhea

• Menstrual dysfunction

• Presence of goiter

• Tremor

• Lid lag, retraction, or both

• "Plumber's nails" (onycholysis)

•

Thyroid bruit

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657

Table 1 1-4. Common Causes of Hyperthyroidism

Cause

Description

Graves' disease

A familial, auroimmune disorder responsible for

approximately 80-90% of hyperthyroid cases.

Occurs more commonly in women than men.

Distinguishing features include diffuse thyroid enlargement, ophthalmopathy (double vision and sensitivity

to light), exophthalmos (excessive prominence of the

eyes), pretibial myxedema (thickening, redness, and

puckering of skin in the front of the tibia), atrial

fibrillation, fine hand tremors, and weakness of the

quadriceps muscle.

Thyroiditis

Inflammation of the thyroid gland can result from an

acute bacterial infection, a subacute viral infection, or

chronic inflammation with unknown etiology.

Pain may or may nor be present on palpation of rhe

gland.

Toxic nodular and

Areas of the enlarged thyroid gland (goiter) become