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Hypothyroidism Complete Guide Causes Symptoms Diagnosis and Treatment

Author: Medical Editorial Team – Board-certified physicians with 10+ years in emergency medicine. Learn more.

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About the Author: Dr. Dinesh, MBBS, is a qualified medical doctor with over [2 years – add your experience] of experience in general medicine As the owner and lead content creator of LearnWithTest.pro, Dr. Dinesh ensures all articles are based on evidence-based guidelines from sources like WHO, CDC, and peer-reviewed journals. This content is for educational purposes only and not a substitute for professional medical advice.

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Frequently Asked Questions

What is hypothyroidism?

Hypothyroidism is a condition in which the thyroid gland produces insufficient amounts of thyroid hormones (T4 and T3), leading to a generalized slowing of metabolic processes in the body.

What is the most common cause of hypothyroidism?

The most common cause is Hashimoto thyroiditis, an autoimmune disorder in which antibodies destroy thyroid tissue.

What are the typical symptoms of hypothyroidism?

Common symptoms include fatigue, cold intolerance, weight gain, constipation, dry skin, hair loss, depression, bradycardia, and menstrual irregularities.

How is hypothyroidism diagnosed?

Diagnosis is primarily made by laboratory testing showing elevated TSH with low free T4 in primary hypothyroidism.

What is subclinical hypothyroidism?

Subclinical hypothyroidism is defined by elevated TSH levels with normal free T4 levels, often with mild or no symptoms.

When should subclinical hypothyroidism be treated?

Treatment is recommended when TSH is greater than 10 mIU/L, in symptomatic patients, during pregnancy, or when anti-TPO antibodies are positive.

What is the treatment of choice for hypothyroidism?

Levothyroxine (synthetic T4) is the treatment of choice and is usually required lifelong in primary hypothyroidism.

How should levothyroxine be taken?

Levothyroxine should be taken orally on an empty stomach, preferably in the morning, 30–60 minutes before food, and separated from calcium or iron supplements by at least 4 hours.

How is treatment monitored in hypothyroidism?

TSH levels are monitored every 6–8 weeks after starting or adjusting therapy, and once stable, every 6–12 months.

Why is TSH unreliable in secondary hypothyroidism?

In secondary hypothyroidism, pituitary dysfunction leads to inappropriately normal or low TSH, so free T4 is used for monitoring.

What complications can occur if hypothyroidism is untreated?

Complications include hyperlipidemia, cardiovascular disease, infertility, anemia, hyponatremia, and myxedema coma.

What is myxedema coma?

Myxedema coma is a life-threatening complication of severe hypothyroidism characterized by hypothermia, altered mental status, bradycardia, and respiratory failure.

Why are steroids given before thyroid hormone in myxedema coma?

Steroids are given to prevent precipitating adrenal crisis due to possible coexisting adrenal insufficiency.

Does hypothyroidism affect pregnancy?

Yes, untreated hypothyroidism increases the risk of miscarriage, preeclampsia, and impaired fetal neurodevelopment.

Is hypothyroidism a lifelong condition?

In most cases, especially autoimmune hypothyroidism, it is lifelong and requires continuous thyroid hormone replacement.

MCQ Test - Hypothyroidism Complete Guide Causes Symptoms Diagnosis and Treatment

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1 A 45-year-old woman presents with fatigue, cold intolerance, weight gain, and constipation. Her labs show TSH 22 mIU/L and free T4 below normal. What is the most likely diagnosis?

Explanation:

Markedly elevated TSH with low free T4 is diagnostic of primary hypothyroidism due to thyroid gland failure.

2 A patient has TSH 7.8 mIU/L, normal free T4, and positive anti-TPO antibodies. She is asymptomatic. What is the best next step?

Explanation:

Subclinical hypothyroidism with positive anti-TPO antibodies has a high risk of progression and warrants treatment.

3 A 70-year-old man with ischemic heart disease is newly diagnosed with hypothyroidism. How should levothyroxine be initiated?

Explanation:

Elderly patients and those with coronary artery disease require cautious low-dose initiation to avoid precipitating angina or arrhythmias.

4 A postpartum woman develops hypothyroid symptoms 6 months after delivery. Anti-TPO antibodies are positive. What is the most likely diagnosis?

Explanation:

Postpartum thyroiditis is autoimmune and commonly presents with a hypothyroid phase months after delivery.

5 A patient on levothyroxine has persistent hypothyroid symptoms despite normal TSH levels. What should be evaluated first?

Explanation:

Poor adherence and reduced absorption due to drug or food interactions are common causes of persistent symptoms.

6 A patient takes levothyroxine with calcium and iron supplements every morning. What is the major consequence?

Explanation:

Calcium and iron significantly impair levothyroxine absorption and should be taken at least 4 hours apart.

7 A newborn screening reveals very low T4 and markedly elevated TSH. What is the most important immediate action?

Explanation:

Early treatment of congenital hypothyroidism is critical to prevent irreversible neurodevelopmental delay.

8 A patient presents with hypothermia, bradycardia, hyponatremia, and altered consciousness. What is the diagnosis?

Explanation:

Myxedema coma is a life-threatening manifestation of severe untreated hypothyroidism.

9 Which treatment should be initiated immediately in suspected myxedema coma?

Explanation:

IV thyroid hormone plus stress-dose steroids is required to avoid precipitating adrenal crisis.

10 A patient has low free T4 with inappropriately normal TSH levels. What is the most likely diagnosis?

Explanation:

Secondary hypothyroidism results from pituitary dysfunction, leading to inadequate TSH response.

11 In secondary hypothyroidism, which parameter is best used to monitor therapy?

Explanation:

TSH is unreliable in secondary hypothyroidism; free T4 guides dose adjustment.

12 A hypothyroid patient presents with menorrhagia. What is the underlying mechanism?

Explanation:

Hypothyroidism causes anovulatory cycles due to altered hypothalamic-pituitary-ovarian axis regulation.

13 A hypothyroid patient has elevated LDL cholesterol levels. What is the primary mechanism?

Explanation:

Reduced thyroid hormone decreases LDL receptor activity, leading to hypercholesterolemia.

14 Which neuromuscular finding is classically associated with hypothyroidism?

Explanation:

Delayed relaxation of deep tendon reflexes is a classic sign of hypothyroidism.

15 Before initiating levothyroxine therapy, which condition must always be excluded?

Explanation:

Untreated adrenal insufficiency can precipitate adrenal crisis when thyroid hormone therapy is started.

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