Endocrinology Flashcards
Define impaired fasting glucose (IFG) and impaired glucose tolerance (IGT) and explain the criteria
A fasting glucose greater than or equal to 6.1 but less than 7.0 mmol/l implies impaired fasting glucose (IFG)
Impaired glucose tolerance (IGT) is defined as fasting plasma glucose less than 7.0 mmol/l and OGTT 2-hour value greater than or equal to 7.8 mmol/l but less than 11.1 mmol/l
Diabetes UK suggests:
‘People with IFG should then be offered an oral glucose tolerance test to rule out a diagnosis of diabetes. A result below 11.1 mmol/l but above 7.8 mmol/l indicates that the person doesn’t have diabetes but does have IGT.’
Define subclinical hypothyroidism; When would you start someone on thyroxine treatment with suspected subclinical hypothyroidism?
Subclinical hypothyroidism with TSH level of level is 5.5 - 10mU/L: offer patients < 65 years a 6-month trial of thyroxine if TSH remains at that level on 2 separate occasions 3 months apart and they have hypothyroidism symptoms
What is the first-line treatment for prolactinomas?
Dopamine agonists (e.g. cabergoline, bromocriptine) are first-line treatment for prolactinomas, even if there are significant neurological complications
Surgery is performed for patients who cannot tolerate or fail to respond to medical therapy
First line treatment for phaeochromocytoma?
PHaeochromocytoma - give PHenoxybenzamine (an alpha blocker) before beta-blockers
Giving a beta blocker before an alpha-blocker in patients with a phaeochromocytoma can cause a hypertensive crisis and so is not the first line treatment in this case.
Surgery is the definitive treatment for a phaeochromocytoma as the tumour releasing the catecholamines needs to be removed. However, this will be done when the patient has been stabilised on alpha and beta blockers, normally around 10 days after treatment is started.
Outline how diabetes can be diagnosed with either fasting glucose of HBA1C
The diagnosis of type 2 diabetes mellitus can be made by either a plasma glucose or a HbA1c sample. Diagnostic criteria vary according to whether the patient is symptomatic (polyuria, polydipsia etc) or not.
If the patient is symptomatic:
fasting glucose greater than or equal to 7.0 mmol/l
random glucose greater than or equal to 11.1 mmol/l (or after 75g oral glucose tolerance test)
If the patient is asymptomatic the above criteria apply but must be demonstrated on two separate occasions.
When HbA1c is used for the diagnosis of diabetes:
a HbA1c of greater than or equal to 48 mmol/mol (6.5%) is diagnostic of diabetes mellitus
a HbAlc value of less than 48 mmol/mol (6.5%) does not exclude diabetes (i.e. it is not as sensitive as fasting samples for detecting diabetes)
in patients without symptoms, the test must be repeated to confirm the diagnosis
it should be remembered that misleading HbA1c results can be caused by increased red cell turnover (see below)
A patient with Addison’s is constantly vomiting, what should you do with their regular oral medications?
What is they are ill and can tolerate their oral medications?
A person with Addisons’ who vomits should take IM hydrocortisone until vomiting stops. (GP usually provides hydrocortisone injection kit)
Addison’s patient with intercurrent illness → double the glucocorticoids, keep fludrocortisone dose the same
What is the target HBA1C for metformin mono therapy?
58mmol/mol, or 7.5%; another drug is added if the HBA1C goes above this
Note that if someone has cardiovascular disease, an addition of SGLT2 inhibitor is recommended even if they are below this target on mono therapy.
When should a GLP-1 agonist be continued in a patient with T2DM?
GLP-1 receptor agonists should only be continued if there is a reduction of at least 11 mmol/mol [1.0%] in HbA1c and a weight loss of at least 3% of initial body weight in 6 months.
low T3/T4 and low/normal TSH with acute illness and no hypothyroidism symptoms = ?
Sick euthyroid syndrome
Clinically, SES is characterised by an absence of hypothyroid symptoms. This absence is a distinguishing feature that differentiates SES from true hypothyroidism.
Whilst anti-thyroid peroxidase antibodies are seen in 90% of Hashimoto’s disease they are also seen in 75% of patients with Graves’ disease. So how would you differentiate the two diseases if this antibody is positive?
Hashimoto’s causes hypothyroidism whilst Grave’s causes hyperthyroidism
What is the main cause of hypothyroidism in the UK?
Autoimmune thyroiditis (Hashimoto’s) is the most common cause of hypothyroidism and is associated with other autoimmune diseases.
In Addison’s disease, what are common results of a patients Na, K and glucose?
Hyponatremia, hyperkalaemia and hypoglycaemia
How is the diagnosis confirmed in a patient with clinically suspected acromegaly, and an elevated or equivocal serum IGF-1 level?
the diagnosis should be confirmed by finding a lack of GH suppression (on serial measurements) with an OGTT.
Which conditions could cause falsely high HBA1C and which could cause falsely low?
Sickle-cell anaemia and other haemoglobinopathies such as hereditary spherocytosis and G6PD deficiency reduce RBC lifespan and hence can artificially lower HbA1c levels.
Splenectomy, iron-deficiency anaemia, B12 deficiency and alcoholism are all associated with falsely high HbA1C readings.
What is the single most important blood test to assess a patient’s response to treatment with levothyroxine for Hashimoto’s thyroiditis?
TSH
