Diabetes and Endocrinology Station Flashcards
What pathological conditions are associated with an abnormal thyroid exam?
Diffuse goitre
Multinodular goitre
Solitary thyroid nodule
Thyroid malignancies
Hyperthyroidism/Graves’ disease
Hypothyroidism
Thyroiditis
Please state 5 clinical signs linked to hyperthyroidism?
What are the clinical signs specific to Graves’ disease?
Tremor
Increased temperature
Increased heart rate
Exophthalmos
Pretibial myxoedema
How do thyroglossal cysts form?
Pretibial myxoedema
Bruit on auscultation of the thyroid gland
Lid retraction
Ophthalmoplegia on the H test
Exophthalmos
How could you confirm a lesion is a thyroglossal cyst on clinical examination?
Thyroglossal cysts occur due to the persistence of the thyroglossal duct
This duct is the route the thyroid gland descends during embryological development
Thyroglossal cysts will rise in tongue protrusion as the duct is attached to the tongue
Why may Graves’ disease cause a bruit when auscultating the thyroid gland?
A bruit is caused by increased vascularity. This occurs in Graves’ disease
Other than optimising glycaemic control, what is the management for the diabetic foot?
Management triad:
– Infection management (antibiotics including anaerobic cover)
– Revascularisation
– Mechanical offloading (reduce pressure on area or they will not heal)
How would you describe an ulcer after you note one on clinical examination?
Size
– Site
– Characteristics: shape, edge, colour
– Secondary features
Outline the physiological mechanism controlling cortisol release
The hypothalamus produces cortisol releasing hormone (CRH) in response to stress and the body’s natural circadian rhythm
CRH causes the anterior pituitary to produce adrenocorticotropic hormone (ACTH)
ACTH stimulates the adrenal cortex to release cortisol
Cortisol negatively feeds back onto the hypothalamus and pituitary to reduce the release of further CRH and ACTH
How does Cushing’s syndrome present?
Symptoms of Cushing’s syndrome
Lethargy
Menstrual changes
Weight gain
– Excess sweating
Signs of Cushing’s syndrome
Central obesity
Abdominal striae
Cushingoid facial changes
Dorsal fat pad
Hypertension
Proximal muscle weakness
Other features
Abnormal glucose tolerance
What is the difference between Cushing’s syndrome and Cushing’s disease?
Cushing’s syndrome is a collection of symptoms caused by excess cortisol. This can be due to any of the causes above.
Cushing’s disease specifically refers to the pituitary gland secreting too much ACTH, which in turn leads to excess cortisol. This is caused by a pituitary adenoma.
Please list some causes of Cushing’s syndrome
Exogenous
Prolonged glucocorticoid use
Endogenous
Pituitary adenoma secreting excess ACTH
Ectopic ACTH secretion (most commonly from small cell lung cancer)
Adrenal adenoma secreting excess cortisol
What investigations are required to localise the cause of cortisol excess?
First, confirm excess cortisol
24-hour urinary free cortisol used to calculate cortisol/creatinine ratio
Or low-dose dexamethasone suppression test
Measure plasma ACTH to help localise the site of excess cortisol release
Undetectable/low ACTH = adrenal pathology, as the functioning pituitary has been switched off by negative feedback; proceed to CT of the adrenal glands
High ACTH = proceed to high dose dexamethasone-suppression test (ACTH from a pituitary tumour is still suppressible at high exogenous steroid doses, whereas ectopic ACTH is not)
If cortisol is not suppressed, CT thorax (look for ectopic ACTH source)
If cortisol is suppressed, MRI pituitary – if tumour not seen, it may be too small to visualise and bilateral petrosal sinus sampling may be required to make diagnosis
Discuss the different management options available for Cushing’s syndrome
Treat cause
Transsphenoidal surgery for pituitary adenomas; pituitary radiotherapy is used as an adjuvant if a surgical cure is not achieved.
Laparoscopic or open adrenalectomy for adrenal tumours
Adjunctive medical therapies (if required for symptoms)
They work by directly inhibiting glucocorticoid synthesis and secretion within the adrenal gland
Examples
Metyrapone
Ketoconazole
What are some potential causes of acromegaly?
Pituitary adenoma leading to unregulated growth hormone (GH) secretion. These may be microadenomas (<1cm) or macroadenomas (≥1cm). These cause the vast majority of cases of acromegaly.
Secondary cancers such as lung, pancreatic or ovarian cancer which secrete ectopic GH or growth hormone releasing hormone (GJRH) are rare but other possible causes
How would you investigate for acromegaly?
- Measure serum IGF-1 levels. This is a very sensitive initial test.
- Oral glucose tolerance test (OGTT); GH would normally be inhibited by glucose. In patients with acromegaly the GH remains >1.0 mcg/L confirming the diagnosis. This is a very specific test.
- MRI scan of the pituitary
- Referral to ophthalmology for visual field testing
- Pituitary function tests and serum prolactin: to rule out coexistent hypopituitarism
What is the surgical management of acromegaly?
Trans-sphenoidal surgery
– Any patients with residual disease can be offered adjuvant medical treatment
– Large invasive tumours can be treated with radiotherapy
Can you discuss different medical managements available and their mechanism of action?
Somatostatin analogues
Examples include octreotide and lanreotide
These are first line
They directly inhibit the secretion of growth hormone
Dopamine agonists
Examples include cabergoline and bromocriptine
They bind to the D2 receptor and reduce GH secretion in some patients
Cabergoline is the safest and most effective dopamine agonist
GH receptor antagonist
An example is Pegvisomant
They decrease fasting glucose and improve glucose tolerance
May raise liver enzymes and so monthly LFT’s are needed for the first six months and then every six months
Which additional investigations are required in monitoring patients with acromegaly?
- Thyroid ultrasound if there is a palpable thyroid nodularity to investigate for thyroid cancer
- Colonoscopy from the age of 40, every 3-5 years, to screen for colorectal cancer
- Echocardiogram to monitor for heart failure
- DEXA scan to assess osteoporosis
- Blood pressure monitoring for hypertension
- Screen for diabetes as acromegaly is strongly associated with type 2 diabetes
- IGF-1 measurements to investigate recurrence
Which surrounding structures may a large goitre compress? Which symptoms would result?
– Trachea compression → breathlessness
– Recurrent laryngeal nerve damage → dysphonia
– Oesophageal compression → dysphagia
– Superior vena cava obstruction → facial swelling, dizziness, headache, blurred vision, syncope
– Pre-ganglionic Horner’s syndrome → ptosis, meiosis, anhidrosis
What is Pemberton sign?
When patients with a retrosternal goitre raise their arms, the thyroid gland can obstruct the thoracic inlet and result in SVC obstruction. This results in facial congestion and cyanosis.
What are the possible complications of Cushing’s syndrome?
– Impaired glucose tolerance and diabetes mellitus
– Hypertension
– Osteoporosis
What is Nelson’s syndrome?
Symptoms resulting from rapid enlargement of a pre-existing pituitary tumour after bilateral adrenalectomy
How do metyrapone and ketoconazole work in Cushing’s syndrome?
Both drugs inhibit enzymes involved in adrenal steroidogenesis:
– Metyrapone inhibits 11β-hydroxylase
– Ketoconazole inhibits 11β-hydroxylase and 17,20-lyase
What are some possible complications of acromegaly?
– Impaired glucose tolerance (40%) and diabetes mellitus
– Cardiomyopathy
– Colon cancer (colonoscopy surveillance)
Which hormones are secreted from the anterior pituitary gland?
– Growth hormone
– Prolactin
– Thyroid-stimulating hormone
– Adrenocorticotropic hormone
– Follicle-stimulating hormone
– Luteinizing hormone
Which hormones are secreted from the posterior pituitary gland?
– Antidiuretic hormone
– Oxytocin
Which other conditions may vitiligo be associated with?
– Other autoimmune conditions (e.g. thyroid disease, pernicious anaemia, diabetes, Addison’s disease)
– 20% of cases are familial
What may trigger vitiligo lesions?
Lesions may be triggered by stress, skin trauma or exposure to chemicals
What is a halo naevus?
Normal mole with a depigmented ring (‘halo’) around it.
Features of Cushing’s
Causes of Cushing’s syndrome?
Common indications for long-term corticosteroid Rx
Ix of non-iatrogenic Cushing’s syndrome
Treatment of acromegaly
∆∆ proximal myopathy
Neurofibromatosis
∆∆ erythema nodosum
∆∆ ulcer by type of edge
Warning signs of a melanoma (ABCDE)
