Hypothyroidism
All the following are causes of primary hypothyroidism EXCEPT:
Treatment at a glance
- Levothyroxine about 1.6 µg/kg daily on an empty stomach
Hypothyroidism
- Hypothyroidism is the insufficient production of thyroid hormones, leading to metabolic slowing.
- Iodine Deficiency : Leads to Endemic Goiter as the gland enlarges under constant TSH stimulation to capture trace iodine.
- Hashimoto’s Disease : Autoimmune destruction of the thyroid gland (chronic thyroiditis).
- Congenital Hypothyroidism : Can lead to cretinism (stunted physical and mental development) if untreated.
- Clinical Features : Fatigue, weight gain, cold intolerance, bradycardia, and constipation.
Read this in Gastric Acid Secretion and Thyroid Disorders
What our notes say
- All the following are causes of primary hypothyroidism EXCEPT: (Internal Medicine 4th Year Endocrinology CAT: 30 MCQs)
- When it is caused by hypothyroidism, thyroid hormone treats it. (Year 6 Gynaecology CAT 1 (MBOG 6511): 13 December 2019, 4 short answers and 16 M)
- Hypothyroidism (often lithium-induced) is linked to rapid cycling. (Psychiatry Year 4 CAT: June 2023, schizophrenia, dementia, eating disorders and )
- Primary hypothyroidism is treated with lifelong levothyroxine, with the dose adjusted by TSH. (Endocrinology and Gastroenterology Question Bank: 12 Clinical MCQs)
- Side effects: tremor, thirst and polyuria, weight gain, hypothyroidism, kidney damage with long use. (Introduction to Psychopharmacology)
- TSH/thyroid function (hyperthyroidism mimics mania; lithium causes hypothyroidism). (Bipolar and Related Disorders)
Study material on Hypothyroidism
- ENDOCRINE PATHOLOGY
- Thyroid Hormone
- Chemical pathology and Endocrine pathology
- LECTURE 4: Thyroid Hormones
- Chemical Pathology Practice Examination
- Integrated case paper: Medicine, Surgery, Gynaecology and Paediatrics (160 marks)
- Review Questions
- Internal Medicine (MBIM 4100) main exam, Paper One: 3 July 2019
- Chemical Pathology MCQs
- Paediatrics end of fourth year special supplementary exam: August 2019, Paper One, 87 of 100 MCQs
- Thyroid Hormone Physiology and Pathology
- Chemical Pathology MCQS
Practice questions on Hypothyroidism
In primary hypothyroidism, TSH levels are typically
- High
- Low
- Normal
- Undetectable Correct
Answer: A. Primary hypothyroidism involves thyroid gland failure, so TSH is elevated due to loss of negative feedback from low thyroid hormones. ---
A patient with primary hypothyroidism will have
- Low TSH, low Free T4
- High TSH, low Free T4
- Low TSH, high Free T4
- High TSH, high Free T4
Answer: B. Primary hypothyroidism is failure of the thyroid gland itself. The pituitary tries to compensate by increasing TSH production, leading to high TSH and low Free T4. Central hypothyroidism has low/normal TSH with low Free T4. ---
What lipid abnormality is associated with hypothyroidism?
- Low LDL and low total cholesterol
- Elevated total cholesterol and LDL cholesterol
- High HDL only
- Low triglycerides
Answer: B. ** Hypothyroid dyslipidemia is characterized by elevated total cholesterol and LDL cholesterol due to decreased LDL receptor activity caused by thyroid hormone deficiency. ---
In subclinical hypothyroidism, which pattern is seen?
- Low TSH, normal fT4
- Elevated TSH, normal fT4
- Elevated TSH, low fT4
- Normal TSH, low fT4
Answer: B. TSH rises to compensate before fT4 falls below normal — the subclinical stage. ---
Congenital hypothyroidism newborn screening measures
- TSH alone
- T4 alone
- TSH and/or T4 on dried blood spot
- TRH stimulation
Answer: C. Programs vary; most use TSH ± T4 on Guthrie card within 48–72 hours of birth. ---
Myxedema coma is the most severe form of hypothyroidism. It presents with
- Hyperthermia, agitation, and tachycardia
- Hypothermia, bradycardia, hypoventilation, and altered consciousness
- Exophthalmos and pretibial myxedema
- High TSH with normal T4
Answer: B. Myxedema coma = decompensated severe hypothyroidism. Precipitated by cold, infection, or sedatives in elderly. Features: hypothermia, bradycardia, hypoventilation, hyponatremia, hypoglycemia, altered consciousness. Treatment: IV T3/T4 + hydrocortisone + supportive care. ---