Each one of the following is associated with pseudohypoparathyroidism, EXCEPT:
Correct Answer B:
Hypoparathyroidism
Primary hypoparathyroidism:
The main symptoms of hypoparathyroidism are secondary to hypocalcaemia:
Pseudohypoparathyroidism:
Pseudopseudohypoparathyroidism:
Which one of the following skin disorders is least associated with hypothyroidism?
Correct Answer C: For the purposes of postgraduate exams pretibial myxoedema is associated with thyrotoxicosis. There are however case reports of it been found in hypothyroid patients, especially the diffuse nonpitting variety.
Skin disorders associated with thyroid disease: Skin manifestations of hypothyroidism:
Skin manifestations of hyperthyroidism:
Pruritus can occur in both hyper- and hypothyroidism.
Cushing's syndrome is most typically associated with which one of the following abnormalities:
Correct Answer D: Cushing's syndrome - hypokalaemic metabolic alkalosis.
Cushing's syndrome: investigations: Investigations are divided into confirming Cushing's syndrome and then localizing the lesion. A hypokalaemic metabolic alkalosis may be seen, along with impaired glucose tolerance. Ectopic ACTH secretion (e.g. secondary to small cell lung cancer) is characteristically associated with very low potassium levels. An insulin stress test is used to differentiate between true Cushing's and pseudo-Cushing's.
Tests to confirm Cushing's syndrome: The two most commonly used tests are:
Localization tests: The first-line localization is 9am and midnight plasma ACTH (and cortisol) levels. If ACTH is suppressed then a non-ACTH dependent cause is likely such as an adrenal adenoma.
High-dose dexamethasone suppression test:
CRH stimulation:
Petrosal sinus sampling of ACTH may be needed to differentiate between pituitary and ectopic ACTH secretion.
An insulin stress test is most useful in the investigation of:
Correct Answer D: Insulin stress tests are also occasionally used to differentiate Cushing's from pseudo-Cushing's.
Insulin stress test: Basics:
Contraindications:
A 34-year-old female with a history of Addison's disease presents for review in endocrinology clinic. She is generally well but complains of a decrease in her libido. On examination there is a slight loss of pubic hair.
What is the most likely cause?
Correct Answer E: Dehydroepiandrosterone is the most abundant circulating adrenal steroid. Adrenal glands are the main source of dehydroepiandrosterone in females - loss of functioning adrenal tissue as in Addison's disease may result in symptoms secondary to androgen deficiency, such as loss of libido. Research is ongoing as to whether routine replacement of DHEA is beneficial.
Addison's disease: Autoimmune destruction of the adrenal glands is the commonest cause of hypoadrenalism in the UK, accounting for 80% of cases.
Features:
Other causes of hypoadrenalism: Primary causes:
Secondary causes:
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