A 52-year-old woman was referred to the clinic having lost 3-4 kg in weight over the previous 3 months. She also had palpitations and a sense of tremulousness. A diagnosis of thyrotoxicosis was confirmed by a blood test arranged by her general practitioner (GP).
Investigations (arranged by GP):
serum thyroid-stimulating hormone<0.01 mU/L (0.4-5.0)
serum free T435.8 pmol/L (10.0-22.0)
serum free T310.0 pmol/L (3.0-7.0)
On examination at her first clinic visit, she had a fine tremor, her pulse was 92 beats per minute and regular, and her eyes appeared normal. Her right thyroid lobe was moderately enlarged, and her left lobe was normal on examination. There was no associated lymphadenopathy. A technetium-99m thyroid isotope uptake scan was arranged (see image).

What is the most likely cause of her thyrotoxicosis?

• A. Graves' disease
• B. de Quervain's thyroiditis
• C. factitious thyrotoxicosis
• D. toxic thyroid adenoma
• E. toxic multinodular goitre

A 29-year-old woman presented with primary infertility, having had unprotected sexual intercourse for 15 months. Menarche had occurred at the age of 13.5 years. Her menstrual cycle was irregular, occurring every 20-60 days. There was no history of galactorrhoea. She denied abnormal hair growth.
On examination, her body mass index was 28.9 kg/m2 (18-25) and she had normal secondary sexual characteristics. Her visual fields were full to confrontation.
Investigations:
serum androstenedione12.8 nmol/L (0.6-8.8)
serum oestradiol205 pmol/L (200-400)
serum testosterone2.4 nmol/L (0.5-3.0)
serum sex hormone binding globulin23 nmol/L (40-137)
serum follicle-stimulating hormone4.3 U/L (2.5-10.0)
serum luteinising hormone8.5 U/L (2.5-10.0)
serum prolactin420 mU/L (<360)
hysterosalpingogrampatent fallopian tubes
partner's semen analysisnormal sperm count and motility
What is the most appropriate first-line intervention?

• A. human menopausal gonadotropins
• B. orlistat
• C. cabergoline
• D. metformin
• E. human chorionic gonadotropin

A 56-year-old man attended routine follow-up for treatment of hypogonadism of late onset. His only medication was testosterone undecanoate (1 g intramuscular injection, every 12 weeks). He had started this treatment 12 months previously and last received the injection 1 week before review.
Digital rectal examination was normal.
Investigations (baseline): haemoglobin145 g/L (130-180) haematocrit0.46 (0.40-0.52) serum prostate-specific antigen0.6 ug/L (<4)
Investigations (12 months after treatment):
haemoglobin153 g/L (130-180) haematocrit0.51 (0.40-0.52) serum prostate-specific antigen5.1 ug/L (<4)
What is the most appropriate next step in management?

• A. stop testosterone therapy
• B. decrease testosterone injection frequency to 14 weeks
• C. reassure and repeat blood tests in 12 months
• D. refer for urological assessment
• E. check serum testosterone

A 32-year-old man presented with medullary thyroid cancer, treated by total thyroidectomy. He had a past history of primary hyperparathyroidism, treated by selective parathyroidectomy. Postoperatively, plasma calcitonin was undetectable and serum calcium was in the normal range.
Investigations:
RET genotypeheterozygote codon 634 C>T mutation
What is the most appropriate approach to annual screening for phaeochromocytoma?

• A. MIBG scanning
• B. CT scan of adrenal glands
• C. MR scan of adrenal glands
• D. octreotide scanning
• E. biochemical screening