Homeostatic Imbalances of Thyroid Function

Predictions
TSH levels in patients with primary hypothyroidism are high
Thyroxine (T4) levels in patients with primary hypothyroidism are low
TSH levels in patients with secondary hypothyroidism are low
Thyroxine (T4) levels in patients with secondary hypothyroidism are low
TSH levels in patients with hyperthyroidism are low
Thyroxine (T4) levels in patients with hyperthyroidism are high

Materials and Methods
1. Name the Dependent Variable.
blood levels of TSH and thyroxine and accumulation of radioactive iodine in thyroid 2. Name the Independent Variable.
thyroid activity
3. Name the Controlled Variables. gender, age
4. Why was RIA used to measure Thyroxine while IRMA was used to measure TSH? RIA is used to measures the thyroxine levels in the blood, while the IRMA measures high or low levels of TSH being released. 5. How was it used to observe relative amount of iodine accumulated by thyroid gland? RAI measures the amount of iodine that is absorbed by the thyroid. If there is too much it indicates hyperthyroidism, too little indicates hypothyroidism.

Results
Table 2. Concentration of Thyroxine and Thyroid Stimulating Hormone (TSH) in Blood Serum Normal
Thyroxine (mg/l)
TSH (mIU/l)
Type of thyroid
disorder

0.05-0.14
0.35-4.5

Patient 1
Value
0.02
7.16

Status
Low
High
Primary
Hypothyroidism

Patient 2
Value
0.01
0.15

Status
Low
Low
Secondary
Hypothyroidism

Patient 3
Value
0.29
0.10

Status
High
Low
Hyperthyroidism

1. The normal range for total amount of Thyroxine in serum is 0.05 – 0.14 mg/L. For each patient, type in their serum Thyroxine concentration and indicate if it is lower, within, or higher than the normal range. a. Patient with primary hypothyroidism

Lower than normal
Laboratory Report/ Miranda Tefft/ Homeostatic Imbalances of Thyroid Function/ Aline Potvin/ 11.18.2014/ Page [1] of [3]

b. Patient with secondary hypothyroidism
Lower than normal
c. Patient with hyperthyroidism
Higher than normal

2. The normal range for serum TSH is 0.35 – 4.5 mIU/L . For each patient, type in her serum TSH concentration and indicate if it is lower, within, or higher than the normal range.
a. Patient with primary hypothyroidism
Higher than normal
b. Patient with secondary hypothyroidism
Lower than normal
c. Patient with hyperthyroidism
Lower than normal

3. For each patient, state whether her thyroid image indicates whether their iodine uptake is low, normal, or high. a. Patient with primary hypothyroidism
This is low intake
b. Patient with secondary hypothyroidism
Low intake
c. Patient with hyperthyroidism
High intake.

Discussion
1. For each subject, indicate whether her TRH levels would be low, normal, or high. Please explain your decision. Discuss negative feedback control in your answer.
a. Subject with primary hypothyroidism
TRH level would be normal. The Pituitary gland is functioning normally, which means that the problem lies in the thyroid. The T4 level is low, so the body tries to counteract that by producing more TSH. By producing more TSH the body tries to produce more T4, which doesn’t happen. b. Subject with secondary hypothyroidism

The TRH level would be low. The low TRH level means that the Pituitary gland isn’t being stimulated to produce enough TSH. This also means that there isn’t enough T4.
c. Subject with hyperthyroidism.
The TRH level would be high. This causes the body to produce too much T4.

2. For each subject, explain why iodine uptake would be greater or less than normal. a. Subject with primary hypothyroidism
The Iodine uptake would be less than normal. This is because the body doesn’t produce enough Thyroid. This means that there is less thyroid to uptake the iodine in the body. Generally the iodine absorbed by the body with Primary hypothyroidism is greater than those with secondary hypothyroidism. (not always the case)

b. Subject with secondary hypothyroidism
The amount of Iodine that is absorbed by the body is less than normal. This is because there is a low amount of T4 and TSH. This lessens the amount of thyroid available to uptake the iodine.
c. Subject with hyperthyroidism.
The iodine uptake with hyperthyroidism is greater than normal. This means that the body produces too much thyroid, meaning there is too much thyroid absorbing the iodine. This causes the iodine up take to be too much.

3. State how hypothyroidism affects each of the following and describe the mechanism by which this change occurs. Laboratory Report/ Miranda Tefft/ Homeostatic Imbalances of Thyroid Function/ Aline Potvin/ 11.18.2014/ Page [2] of [3]

a. body temperature
Hypothyroidism can affect the body temperature because it slows down the metabolism. This causes the energy produced to be less. With that being said, the bodies functions slow down so the body temperature drops. b. heart rate

Hypothyroidism decreases the heart rate. This is because the body functions slow down. When the body functions slow down, the heart doesn’t need to work as hard and as fast to maintain homeostasis.

4. State how hyperthyroidism affects each of the following and describe the mechanism by which this change occurs. a. body temperature
The body temperature is affected by hyperthyroidism. The body temperature rises because the metabolism is sped up. There is more energy that is produced and the organs in the body are functioning faster than normal increasing the body temperature. b. heart rate

The heart rate is increased when there is hyperthyroidism present in the body. This is because the bodies functions are sped up and increased. When this is happening the heart has to work harder and faster to maintain sufficient blood flow.

5. Restate your predictions that were correct and give the data from your experiment that supports them. Restate your predictions that were not correct and correct them, giving the data from your experiment that supports the corrections. All of my predictions were correct. The experiment shows that the subject with Primary Hypothyroidism had High T4 levels and Low TSH levels, the experiment showed that the subject with secondary hypothyroidism had Low T4 levels and Low TSH levels, and it also showed that the subject with hyperthyroidism had high T4 levels and low TSH levels.

Application
1. The subject who was diagnosed with primary hypothyroidism was given levothyroxine (synthetic Thyroxine). After 2 months of treatment, her TSH values decreased by 96.38% and her Thyroxine levels increased by 879.4%. Explain why her TSH levels decreased and Thyroxine increased.

She was given Levothyroxine which aids in hypothyroidism. This is made of T4 and helps replace the T4 that the body can’t. Because the T4 levels increased the TSH no longer was overcompensating to make more T4. The TSH was only high because it tried to produce more to help increase the T4 levels.

2. The subject who was diagnosed with secondary hypothyroidism was given levothyroxine (synthetic Thyroxine). After 6 weeks of treatment, her TSH values did not change and her Thyroxine levels increased by 778.62%. Explain the why TSH did not change and why Thyroxine increased.

The T4 increased due to the levothyroxine. However because the Pituitary glands aren’t functioning properly, the TSH was unable to produce a normal amount of TSH.
3. The subject who was diagnosed with hyperthyroidism was given propylthiouracil (prevents Thyroxine production and conversion of Thyroxine to T3 in the tissues). After 2 months of treatment, her TSH levels increased by 371.15% and her Thyroxine levels decreased by 42.7%. Explain why her TSH levels increased and her Thyroxine levels decreased. This medication makes it harder for the body to produce thyroid. With that being said the level of the T4 decreased. The TSH increased because T4 levels were decreased making it easier for the TSH to be produced at an adequate rate.

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