Posted by Ted (205.188.197.152) on January 29, 2000 at 18:08:54:
May be close to what we're looking for:
Goiter
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Alternative names
simple goiter; euthyroid goiter; nontoxic nodular goiter; nontoxic goiter; nontoxic diffuse goiter
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Definition
An enlargement of the thyroid gland that is not associated with inflammation or cancer.
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Causes, incidence, and risk factors
A simple goiter occurs when the thyroid gland is unable to meet the metabolic demands of the body through sufficient hormone production. The thyroid gland compensates by enlarging, which usually overcomes mild deficiencies of thyroid hormone.
A simple goiter may be classified as an endemic (present continuously in a community) or sporadic goiter. Endemic (also known as colloid) goiters are usually caused by inadequate dietary intake of iodine in certain geographical areas with iodine depleted soil, usually areas away from the sea coast. In the US, the Great Lakes, Midwest, and Intermountain regions are known as the "goiter belt.". The use of iodized table salt prevents this deficiency. The incidence of iodine deficiency is now rare in the U.S. because of widespread distribution of foods from iodine sufficient areas and salt to which potassium iodide has been added.
Sporadic goiters are caused by swallowing of large amounts of certain foods or drugs and does not affect any particular segment of the population. Goitrogenic foods contain substances that decrease thyroid hormone production. Examples of these foods are rutabagas, cabbage, soybeans, peanuts, peaches, strawberries, spinach, and radishes. Drugs include lithium, cobalt, iodides, phenylbutazone, and others.
Hereditary factors may cause goiters. Excessive iodine intake is also a cause of goiter. Risk factors: female gender, over 40 years old, inadequate dietary intake of iodine, residence in an endemic area, ingestion of large amounts of goitrogenic foods or drugs, and a family history of goiters.
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Prevention
The use of iodized table salt prevents endemic goiter. Limiting goitrogenic foods and drugs prevents sporadic goiter.
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Symptoms
thyroid enlargement varying from a single small nodule to massive enlargement, neck lump
breathing difficulties or wheezing from compression of the trachea (rare)
swallowing difficulties from compression of the esophagus
neck vein distention and dizziness when the arms are raised above the head
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Signs and Tests
thyroid scan
ultrasound of thyroid
high or normal thyroid stimulating hormone
low or normal T4
normal or increased radioactive iodine uptake
low urinary excretion of iodine
antithyroid microsomal antibody
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Treatment
Hormone replacement inhibits thyroid stimulating hormone and allows for recovery of the thyroid gland. Small doses of iodine (Lugol's or potassium iodine solution) will treat iodine deficiency. Eliminating or reducing goiter producing foods or drugs is indicated for sporadic goiter. A large goiter that is unresponsive to medical management, or restricts swallowing and breathing, may require partial removal of the gland (subtotal thyroidectomy).
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Expectations (prognosis)
The outcome is expected to be good with treatment. Simple goiters may disappear spontaneously, or may become large. Occasionally a person may develop hyperthyroidism with a nodular goiter after receiving excess iodine therapy. More frequently, hypothyroidism develops.
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Complications
A progressive thyroid enlargement and/or the development of hardened nodules may indicate thyroid malignancy.
A simple goiter may progress to a toxic nodular goiter.
Thyrotoxicosis may be a side effect of treatment.
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Calling your health care provider
Call your health care provider if you experience any swelling or enlargement in the front of your neck, increased resting pulse rate, palpitations, diarrhea, nausea, vomiting, sweating without exercise of increased room temperature, tremors, agitation, shortness of breath, or signs of hypothyroidism.
And then there's this article, of specific interest is under the subtitled "How the test is performed":
T4
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Alternative names
thyroxine test
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Definition
A test that measures the amount of T4 in the blood.
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How the test is performed
Adult or child:
Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend (fill with blood). A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
Infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.
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How to prepare for the test
The health care provider may advise you to withhold drugs that may affect the test (see "special considerations").
Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:
infant test or procedure preparation (birth to 1 year)
toddler test or procedure preparation (1 to 3 years)
preschooler test or procedure preparation (3 to 6 years)
schoolage test or procedure preparation (6 to 12 years)
adolescent test or procedure preparation (12 to 18 years)
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How the test will feel
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
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Risks
Risks associated with venipuncture are slight:
excessive bleeding
fainting or feeling lightheaded
hematoma (blood accumulating under the skin)
infection (a slight risk any time the skin is broken)
multiple punctures to locate veins
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How the test is performed
This test may be performed as part of an evaluation of thyroid function.
TSH is a peptide hormone secreted by the pituitary gland. It stimulates the synthesis and secretion of T4 and T3 (triiodothyronine) from the thyroid gland. TSH is, itself, stimulated by TRH, which is released by the hypothalamus. T3 and T4 feedback inhibit the release of both TSH and TRH in normal people. Most of the thyroid hormone secreted by the thyroid gland is in the form of T4, but T3 is probably the active hormone; i.e., T4 is converted to T3 by target tissues.
T4 is the major hormone controlling the basal metabolic rate. The exact mechanisms are not completely known, but it is known that T4 increases the concentrations of numerous enzymes involved in the production of energy in all nucleated cells of the body. Most of the T4 in the blood is bound to proteins; this acts as a reservoir of available thyroxine because only free T4 is active on cells. T4 appears to be converted to T3 within cells, before it enters the nucleus and interacts direction with DNA, eventually resulting in the production of various proteins by the cell.
Only 0.03% of the T4 in plasma is free (soluble and active) and 0.3% of the T3 is free; the rest is bound to protein. Most of the T3 and T4 are transported by TBG (thyroxine binding globulin), but smaller amounts are found on prealbumin and albumin The available concentrations of T3 and T4 are affected by the level of TBG, which is quantitated by the R3TU test.
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Normal values
4.5 to 12.5 mcg/dl
Note: mcg/dl = micrograms per deciliter
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What abnormal results mean
Greater-than-normal levels may indicate:
hyperthyroid states
Graves' disease
Plummer's disease
thyroid cancer
acute thyroiditis
Lower-than-normal levels may indicate:
hypothyroidism (for example, Hashimoto's disease, cretinism, myxedema)
protein malnutrition
renal failure
Additional conditions under which the test may be performed:
colloid nodular goiter
drug-induced hypothyroidism
goiter
hypopituitarism
hypothyroidism; primary
hypothyroidism; secondary
painless (silent) thyroiditis
thyrotoxic periodic paralysis
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Costs
The estimated cost is $42. (T4 test).
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Special Considerations
Drugs that can increase T4 measurements include clofibrate, estrogens, methadone, and oral contraceptives.
Drugs that can decrease T4 measurements include anabolic steroids, androgens, antithyroid drugs (for example, propylthiouracil), lithium, phenytoin, and propranolol.
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
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