QuestionSBA
QuestionChoice
This value reflects ambient circulating glucose (glycation of Hb) for the last 2-3 months. It is useful for those with suspected type 2 diabetes.
10005102
b
HbA1c
QuestionChoice
In this test basal TSH levels are determined before giving an IV bolus of TRH. TSH levels are measured once again and compared to the baseline.

If there is an increase in TSH this means that the cause of the hypothyroidism is the hypothalamus (tertiary hypothyroidism). If there is no TSH increase or a slight increase this is indicative of the anterior pituitary not secreting TSH. This test would be used if there is normal TSH but low thyroid output.
10005104
d
TRH stimulation test
QuestionChoice
When given dexamethasone, ACTH is downregulated and endogenous cortisol should be suppressed.

This patient likely has Cushing's syndrome, as there is a glucocorticoid excess, cortisol secretion would be autonomous and not responsive to feedback. Therefore cortisol levels will remain high and the test will be positive.
10005101
a
Dexamethasone suppression test (DST)
QuestionChoice
This is a test where exogenous ACTH is given and there should be high cortisol in response to this.

In Addison's disease there is decreased mineralocorticoid and glucocorticoid synthesis. Despite receiving exogenous ACTH there will be low plasma cortisol.
10005103
c
Short synacthen test
QuestionChoice
This is the gold standard for the diagnosis of diabetes. The patient's fasting glucose is measured and the patient is given a 75g glucose drink. After 2 hours, the blood glucose is measured again. These values are then compared to those of a healthy patient.
10005105
e
Oral glucose tolerance test (OGTT)
Concept
Chapter
2693
3764
Cushing's syndrome
Topic
133
Endocrinology
13567
A 45-year-old female patient has presented to her GP with complaints of amenorrhea.

Upon examination, she has central obesity and purple striae, which one of the following tests would you conduct to diagnose the patient?
a