Hypothyroidism Thyroid questions

1. A 17-year-old girl was incidentally detected to have abnormal thyroid function test (TFT)
results, as part of routine tests to ascertain the cause of her tiredness. She denied any weight
gain, menstrual irregularity, cold intolerance, or constipation. She had a strong family history
of thyroid dysfunction with her two elder brothers and maternal uncles suffering from
abnormal thyroid function, although none received any medications. On examination, she had
mild tremors in her hands and a pulse rate of 76 beats/minute with rest of the general
physical and systemic examination being unremarkable.
TFT results:
• free T4 24.4 pmol/L (11.5–19.7)
• free T3 7.8 pmol/L (3.5–6.5)
• TSH 7.2 mU/L (0.35–5.5)
Which one of the following is the most likely diagnosis based on her clinical profile?
A. Pregnancy
B. Prolactinoma
C. Subclinical hyperthyroidism
D. Subclinical hypothyroidism
E. Thyroid hormone resistance

2. E. Thyroid hormone resistance syndrome
it is characterized by elevated FT4 and FT3 in the presence of a non-
suppressed TSH. Resistance to thyroid hormone can be:
• Generalized resistance.
• Selective pituitary resistance.
• Selective peripheral resistance

3. TSH synthesis and secretion is mainly influenced by serum levels of
thyroid hormones (T4 and T3) and, to a certain extent, by a few
hormones and drugs. Which one of the following
medications/hormones stimulates the release of TSH?
A. Arginine-vasopressin
B. Dopamine agonists
C. Glucocorticoids
D. Growth hormone
E. Somatostatin

4. • TSH is a glycoprotein synthesized and secreted by thyrotrophs of the
anterior pituitary gland. It is composed of two subunits, α and β,
linked together by non-covalent bonds. α subunit is common
between other glycoprotein hormones, such as FSH, LH, and β-hCG,
while the β subunit confers it specific biological activity and binding
properties.

5. A 45-year-old man of Indian sub-continent origin presented to the clinic with symptoms of
malaise, weight gain, and cold intolerance. He had a past medical history of primary
autoimmune hypothyroidism and had been taking thyroxine (100 µg/day) for the last 5 years.
He had been reviewed in a respiratory clinic 6 weeks earlier and diagnosed with pulmonary
tuberculosis. As a result, he was initiated on a combination chemotherapy regimen for
tuberculosis, comprising isoniazid, rifampicin, ethambutol, and pyrazinamide.
TFT’s results:
• free T4 10.2 pmol/L (11.5–22.7)
• TSH 10.4 mU/L (0.35–5.5)
• Anti-TPO antibody Positive
Which one of the following is the most likely explanation for his symptoms and biochemistry
results?
A. Flare-up of autoimmune activity with tuberculosis
B. Thyroxine interaction with ethambutol
C. Thyroxine interaction with isoniazid
D. Thyroxine interaction with rifampicin
E. Poor compliance

6. D. This gentleman was on the stable dose of thyroxine and developed
clinical and biochemical features of hypothyroidism 6 weeks after
starting chemotherapy for tuberculosis.
Rifampicin is an inducer of hepatic enzymes and accelerates the
metabolism of several drugs.
In this clinical scenario, his thyroxine dose needs to be increased due to
its interaction with rifampicin.

7. A 44-year-old woman presented to her GP with occasional episodes of palpitations
and flushing lasting for few minutes. These episodes had no obvious precipitating
factor and were not associated with any chest pain or tightness. On examination, she
had resting tremors, a pulse rate of 84 beats/minute with regular rhythm. Her general
physical and systemic examination was unremarkable.
• Investigations:
• free T4 20.2 pmol/L (11.5–22.7)
• TSH 0.25 mU/L (0.35–5.5)
• TSH receptor antibody negative
Which one of the following is the most appropriate management approach, based on
her clinical profile and test results?
A. Commence on carbimazole
B. Commence on β-blockers only
C. Observe and monitor TFTs
D. Radioactive iodine ablation (RAIA)
E. Arrange a thyroid uptake scan

8. • C. This woman has sub-clinical hyperthyroidism as evidenced by a
normal FT4 with a suppressed TSH level. As she has non-specific
symptoms together with a measurable TSH level, with no features of
an exogenous thyroid dysfunction; hence, the management approach
can be conservative at this stage.

9. A 22-year-old man presented to his GP with weight gain, lethargy, and cold
intolerance. He was on thyroxine (125 µg) tablets for primary autoimmune
hypothyroidism. He was also taking insulin (basal-bolus regimen) for Type 1
DM, diagnosed when he was 11 years old.
• TFT results: free T4 22.5 pmol/L (11.5–22.7)
• free T3 6.4 pmol/L (3.5–6.5)
• TSH 8.2 mU/L (0.35–5.5)
Which one of the following is the most appropriate management approach in
his clinical scenario?
A. Counselling regarding compliance with therapy
B. Increase thyroxine dose
C. Reduce thyroxine dose
D. Repeat TFT’s in 6–8 weeks
E. Switch to liothyronine (T3)

10. • A. Poor compliance with thyroxine replacement commonly causes
anomalous TFTs: owing to their differing half-lives, intermittent
hormone ingestion may result in normal or even elevated thyroid
hormone levels, but fails to normalize TSH.

11. A 30-year-old woman who was 8 weeks pregnant presented to the joint antenatal-
endocrine clinic, with mild early morning nausea and tiredness. She was diagnosed
with primary autoimmune hypothyroidism about 5 years ago and was taking
thyroxine (100 µg od) therapy. On examination, she was clinically euthyroid and
systemically well.
TFT results:
• free T4 14.5 pmol/L (11.5–22.7)
• free T3 4.2 pmol/L (3.5–6.5)
• TSH 10.5 mU/L (0.35–5.5)
Which one of the following is the most appropriate management approach in her
clinical scenario?
A. Check anti-TPO antibodies
B. Check compliance
C. Increase thyroxine dose
D. Observe and repeat TFTs in 4–6 weeks
E. Reduce thyroxine dose

12. • C. This pregnant woman has an elevated TSH, despite being on
thyroxine therapy while she is in her first trimester of pregnancy.
• According to the Endocrine Society guidelines, overt as well as sub-
clinical hypothyroidism (TSH >10 mU/L in the presence of normal FT4)
is associated with adverse foetal and maternal outcomes, and needs
to be treated with thyroxine therapy to bring TSH values back to a
trimester specific range.