Endocrine Labs Flashcards by Ashton Fischer

Signs & Symptoms of Hypothyroidism

fatigue or sluggishness
weight gain
cold intolerance
dry skin, brittle hair
constipation, slows digestion
slows heart and respiration
menstrual irregularities

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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

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Can you order a TSH if the patient presents with one symptom alone?

Yes

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Name the 5 thyroid function tests

TSH
Total T4
Total T3
Free T4
Free T3

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Secretion of T4 and T3 by the thyroid gland is regulated by TSH from the?

pituitary

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TSH levels are controlled through…

a negative feedback system

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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

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What is the normal value range for TSH?

0.4-4.2 mU/L for adults

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What is the best test to assess thyroid function?

TSH

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If TSH is normal, does this allow for further testing?

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An elevated TSH points to?

Hypothyroidism

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A low TSH points to?

Hyperthyroidism

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An elevated TSH can be followed with what test?

Free T4 (to determine the degree of hypothyroidism)

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A low TSH can be followed with what test?

Free T4 and possibly a Free T3 (to determine the degree of hyperthyroidism)

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What test is used to monitor therapy in patients with hypothyroidism?

TSH test

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Individuals with hypothyroidism take what thyroid medication?

levothyroxine

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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

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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

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After administering levothyroxine to a patient when should they come back in for a check-up?

4-6 weeks to monitor TSH levels

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What could be reasons for an abnormally elevated TSH level?

Primary hypothyroidism
Medication interactions
Certain tumors

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What could be reasons for an abnormally low TSH level?

Primary hyperthyroidism
Euthyroid sick disease
Thyroid nodules or goiter

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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

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These labs are not commonly used in primary care

Total T4 and Total T3

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These labs increase in hyperthyroidism and decrease in hypothyroidism

Total T4 and Total T3

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These labs measure only the amount of T4 or T3 that is not bound to protein and is therefore immediately available for cellular utilization

Free T4 and Free T3

What test can be ordered to confirm TSH results?

Free T4

This test should be elevated in hyperthyroidism and decreased in hypothyroidism?

Free T4

What test may be used in confirming hyperthyroidism?

Free T3 (in addition to Free T4)

These tests are used routinely to monitor therapy?

TSH, Free T4, and Free T3

If a TSH level is below normal range, what do you think of? And what should you order to confirm it?

Think of Hyperthyroidism | Order FT4 and FT3 to confirm

What should you do if someone has hyperthyroidism?

Refer!

If a TSH level is above normal range, what do you think of? And what should you order to confirm it?

Think of hypothyroidism | Order FT4 to confirm

High TSH and low FT4 confirms hypothyroidism what should you do next?

Start levothyroxine. Monitor with periodic TSH.

High TSH and normal FT4, this is considered?

"subclinical hypothyroidism"

What type of cases of "subclinical hypothyroidism" should be treated?

Treat if symptomatic or TSH>10 or planning pregnancy

High TSH and high FT4, what does this require?

Referral

If labs don't make sense (such as high TSH and high FT3, or low TSH and low FT4), the problem may be what instead? What do you do?

Pituitary and refer

What lab tests can be used to diagnose or to screen for DM?

Fasting blood glucose level (FBG) Glycosylated hemoglobin (HbA1C) Oral glucose tolerance test (OGTT)

What are the symptoms of DM?

polyuria, polydipsia, weight loss, fatigue

What an be used for a patient with symptoms of DM that is used for diagnostic purposes, but not for screening?

Random blood glucose level > or equal to 200mg/dL

What percent of patients with DM have type 1? type 2?

5% with Type 1 DM | 95% with Type 2 DM

Is screening recommended for DM type 1?

If a screening test returns with a positive result what do you do?

Repeat the same test for confirmation

The DM tests have good what _____, but poor _______?

good specificity | poor sensitivity

If a patient has HTN what else do you screen for?

What should the patient do before a fasting blood glucose (FBG)?

Fast for 8 hours

Can the "glucose" in the CMP be utilized for a FBG?

Yes, as long as the patient has been fasting for 8 hours.

A FBG level of greater than or equal to 126 mg/dL on two separate tests confirms?

What is the normal value for FBG?

<100 mg/dL

A value of ______ on a FBG means the patient could have impaired glucose tolerance, and is at risk for DM

100-126 mg/dL

Does the HbA1C require fasting?

What does the A1C reflect?

average blood sugar levels for the 3 month period before he test

An A1C of _____ on 2 separate tests, confirms the diagnosis of DM

>6.5%

Values between _______ are at high risk for developing DM

6.0-6.4%

Values between _______ are considered normal

5.0-6.0%

What could affect the results of HbA1C?

changes to RBCs (e.g., anemia, chronic blood loss, toxicities, renal failure, pregnancy, sickle cell anemia)

This test is considered "first-line" for diagnostic purposes, but is not highly recommended for screening purposes

oral glucose tolerance test (OGTT)

What other non-laboratory exams should a patient with DM have done?

eye, foot, and dental exams | monitoring of BP, weight, diet, exercise, and smoking cessation

Laboratory exams used to monitor patients with DM include:

testing urine for albumin (annually) lipid panel (annually) monitor liver function and renal function through the CMP (annually) A1C to monitor glycemic control (biannually in stable patients, quarterly in unstable patients)

What is the goal for A1C?

A1C <7%