Free UKMLA endocrine and metabolic questions with explanations

C. Cerebral oedema

Cerebral oedema is the most feared complication of DKA treatment, classically presenting 4 to 12 hours after initiation with headache, reduced consciousness, and signs of raised intracranial pressure such as bradycardia, hypertension and papilloedema. It is more common in children and young adults and carries a mortality of around 20 to 25%; urgent management is IV mannitol or hypertonic saline with critical care input (BSPED DKA guideline).

E. Intramuscular glucagon 1 mg

In severe hypoglycaemia with impaired consciousness or unsafe swallow, parenteral therapy is required; IM glucagon 1 mg is appropriate in the community setting where IV access is not immediately available, per the Joint British Diabetes Societies inpatient hypoglycaemia guideline. Glucagon mobilises hepatic glycogen stores, raising blood sugar within 10–15 minutes, after which oral carbohydrate should be given once swallow is safe. In hospital, IV 10% dextrose (150–200 mL) is the alternative.

B. Short Synacthen test

The Short Synacthen (ACTH stimulation) test is the first-line dynamic investigation to confirm primary adrenal insufficiency: 250 micrograms of synthetic ACTH is given IM or IV and serum cortisol measured at 0 and 30 minutes, with a peak below approximately 500 to 550 nmol/L indicating an inadequate adrenal response. In Addison disease the diseased adrenal cortex cannot respond, producing a flat cortisol curve alongside elevated baseline ACTH.

E. IV hydrocortisone 100 mg at induction, then 50 mg 6-hourly for 24 hours

Patients with primary adrenal insufficiency cannot mount an endogenous cortisol stress response and require parenteral glucocorticoid cover to prevent intraoperative Addisonian crisis. Society for Endocrinology UK guidance for major surgery recommends IV hydrocortisone 100 mg at induction followed by 50 mg 6-hourly (or a 200 mg/24 h continuous infusion) for 24 hours, then doubling the usual oral dose for 48–72 hours before returning to maintenance.

E. Free T4

In primary hypothyroidism the pituitary senses thyroid hormone levels and TSH is the sensitive guide to dosing, but in secondary (central) hypothyroidism the pituitary is the diseased organ, so TSH is low or inappropriately normal whatever the dose and cannot be used. Levothyroxine is therefore titrated to keep the free T4 in the upper half of the reference range, alongside symptoms. Free T3 fluctuates and is largely derived from peripheral conversion, and total T4 is distorted by binding-protein changes (for example on oestrogen), so neither is the standard monitoring test. Hydrocortisone must already be in place before thyroid replacement is started or increased.

A. Graves' disease

Graves' disease is an autoimmune thyrotoxicosis caused by stimulating TSH receptor antibodies, producing a diffuse smooth goitre (often with bruit from hypervascularity) and extrathyroidal features such as orbitopathy (proptosis, periorbital oedema, ophthalmoplegia) which is specific to Graves', whereas lid retraction and lid lag occur in thyrotoxicosis of any cause. TRAb testing is recommended to confirm the diagnosis.

B. MRI orbits with fat suppression

MRI of the orbits with fat-suppressed sequences (STIR/T2) is the imaging modality of choice in thyroid eye disease: it shows fusiform extraocular muscle enlargement with tendon sparing, distinguishes active inflammatory oedema from chronic fibrosis, and identifies apical crowding causing optic nerve compression, all without ionising radiation. CT orbits is reserved for surgical planning when bony decompression is being considered (EUGOGO 2021).

B. Anaplastic thyroid carcinoma

Anaplastic thyroid carcinoma characteristically affects elderly patients and presents with a rapidly enlarging, hard, fixed neck mass with early invasion of local structures producing hoarseness (recurrent laryngeal nerve involvement) and stridor (tracheal compression). It is an undifferentiated malignancy with a median survival of around 6 months, and urgent multidisciplinary assessment with airway protection as a priority is recommended.

B. Acanthosis nigricans

Acanthosis nigricans is symmetrical velvety hyperpigmented thickening of flexural skin, most often the neck and axillae, caused by hyperinsulinaemia stimulating keratinocyte and fibroblast growth through insulin-like growth factor receptors. In an obese adult it is a cutaneous marker of insulin resistance and should prompt a check for type 2 diabetes. Rapid onset in an older, non-obese person can signal an internal malignancy, usually gastric adenocarcinoma. Erythrasma is a flat brown intertriginous patch that fluoresces coral-red under Wood's light; pityriasis versicolor is scaly and truncal; post-inflammatory change follows a preceding rash; Addisonian pigmentation affects palmar creases, scars and buccal mucosa with fatigue and hypotension.

B. Breast carcinoma

Men with Klinefelter syndrome have a risk of breast cancer many times that of other men, attributed to the long-standing high oestrogen-to-androgen ratio acting on breast tissue, and it is, with BRCA2 carriers, a male group in whom a breast lump should raise cancer as the first thought. Gynaecomastia, which he already has, is a soft or rubbery, mobile, concentric disc beneath the areola and is usually bilateral; a new unilateral, hard, fixed, eccentric mass with nipple retraction is the pattern of carcinoma, whatever the background. He needs an urgent suspected cancer referral for triple assessment with examination, imaging and core biopsy.