INVESTIGATIONS - endocrine

Question 1

What should you check in someone presenting with hypercalcaemia?

Answer 1

PTH

Question 2

In someone with hypercalcaemia, low PTH, low albumin and low Cl-, what should you be worried about?
What tests might you do?

Answer 2

Malignancy

Consider x-ray, CT, MRI or isotope bone scan

Question 3

Investigation of choice for suspected adrenal insufficiency?
What would the results be?

Answer 3

Short synacthhen test

i.e. measure plasma cortisol levels 30 minutes before and after ACTH injection. In a healthy person, cortisol levels will increase from 250nmol/l to >550.
In someone with adrenal insufficiency, cortisol will be <500 even after ACTH injection.

Question 4

What test can be used to differentiate between primary (adrenal), secondary (pituitary) and tertiary (hypothalamic) adrenal insufficiency?

Answer 4

Serum ACTH

Elevated ACTH = Addison’s / primary disease

Normal or low suggests a pituitary or hypothalamic problem.

Question 5

What will renin and aldosterone levels be in Addison’s disease?

Answer 5

Renin is elevated (to compensate for no aldosterone synthesis in the adrenal cortex)

Aldosterone is suppressed due to non-functioning adrenal cortex (may help to differentiate Addison’s from secondary adrenal insufficiency)

Question 6

Which antibodies may be present in Addison’s disease?

Answer 6

Anti-adrenal autoantibodies

21-hydroxylase antibodies

Question 7

First line test for diagnosing Cushings?

What would the results of this test be?

Answer 7

Overnight dexamethasone suppression test

Healthy person: dexamethasone will trigger negative feedback response resulting in low ACTH and cortisol levels. In Cushing’s there is no such suppression.

Question 8

If the pituitary is the cause of Cushing’s syndrome, what with ACTH levels be?

What would ACTH levels be if the adrenal gland was the cause?

Answer 8

High ACTH = pituitary cause or ectopic ACTH production

Low ACTH = adrenal cause (cortisol release is indpendent of ACTH levels)

Question 9

When is cortisol usually highest, and when is it lowest?

Answer 9

Highest first thing in the morning

Lowest at night

Question 10

Gold standard test for diagnosing pituitary adenoma?

Answer 10

Insulin stress test

Healthy person: It will create an acute hypoglycaemic state, so should trigger cortisol and GH.

Question 11

If prolactin levels are raised, what imaging might you undertake?

Answer 11

MRI to look for pituitary tumour

Question 12

What test is used to diagnose acromegaly?

Answer 12

Glucose tolerance test
(measure growth hormone after glucose is given; GH will be suppressed in a healthy person to <0.4ug/L, but won’t be suppressed in someone with acromegaly)

Can also measure IGF1 which will be elevated (note: IGF1 doesn’t fluctuate much throughout the day)

Question 13

What test is used to confirm diabetes insipidus?

Answer 13

Water deprivation test

Question 14

In diabetes insipidus what will urine osmolarity be?

And what about serum osmolarity?

Answer 14

Low urine osmolarity

High serum osmolarity

Question 15

What investigation may be useful in the diagnosis of Conn’s? Why is this hard to carry out?

Answer 15

Aldosterone : renin ratio
High aldosterone, low renin (due to feedback from aldosterone)

If the R:A ratio is raised, investigate further with saline suppression test.

Patients tend to be on hypertensive medication which alters RAAS making results unreliable.

Question 16

Which enzyme is usually deficient in congenital adrenal hyperplasia?

Answer 16

21 hydroxylase deficiency

Question 17

What test should be carried out in cases of suspected CAH?

Answer 17

Measure 17 OH progesterone levels. Usually elevated in CAH.

Also do genetic analysis

Question 18

What is calcitonin used as a marker for?

Answer 18

Medullary thyroid cancer (cancer of the parafollicular C cells)

Question 19

Which differentiated thyroid cancer spreads via lymphatics? Which one is blood?

Answer 19

Papillary is lymphatics

Follicular is blood

Question 20

Which antibodies may be present in Hashimoto’s thyroiditis?

Answer 20

anti-TPO

thyroid peroxidase

Question 21

Why does medullary thyroid cancer result in hypocalcaemia?

Answer 21

Parafollicular c cells release calcitonin, which lowers calcium levels

Question 22

Which antibodies would increase your suspicion of Graves disease being the diagnosis?

Answer 22

TSH receptor antibody

Question 23

What’s the main risk factor for thyroid cancer?

Answer 23

Radiation

Question 24

What grading on ultrasound of a thyroid nodule would warrant FNA?

Answer 24

U3 with worrying signs, or U4 or U5 should all undergo FNA

Question 25

Which type of thyroid cancer cannot be diagnosed on FNA? WHy is this?

Answer 25

Follicular | Diagnosis requires thyroid lobectomy to assess extent of capsular invasion

Question 26

What is AMES? What does it constitute and what's it used for?

Answer 26

Age Metastasis Extent of primary tumour Size of primary tumour Used post-op to stratify patients as low risk or high risk Low risk: young patients with no evidence of mets. High risk: 40+ (men) or 50+ (women), with invasion / mets, or primary timour >5cm

Question 27

What's the prognosis for AMES high risk? | What about for low risk?

Answer 27

High risk: 61% 20 year survival | Low risk: 99% 20 year survival

Question 28

What are U1, U2, U3, U4 and U5?

Answer 28

``` Ultrasound assessment of thyroid lumps U1 = normal U2 = benign U3 = indeterminate U4 = suspicious U5 = malignant ```

Question 29

Investigations for toxic multinodular goitre?

Answer 29

TSH (should be suppressed) Free T4 (elevated) Iodine uptake scan - multiple hot and cold areas CT may be indicated if signs of neck compression

Question 30

What level of fasting plasma glucose is diagnostic of diabetes?

Answer 30

>7 mmol/l

Question 31

What level of plasma glucose is diagnostic of diabetes following an oral glucose tolerance test?

Answer 31

>11.1 mmol/l two hours after 75g oral glucose load

Question 32

What constitutes impaired glucose tolerance in the context of an oral GGT?

Answer 32

Plasma glucose of 7-11 mmol/l after 2 hours

Question 33

What are glucose levels in hypoglycaemia?

Answer 33

<4 mmol/l

Question 34

What's the criteria for random plasma glucose to give a diagnosis of diabetes?

Answer 34

>11.1 on repeat testing, or with symptoms

Question 35

What's the normal HbA1c in a healthy individual?

Answer 35

<41 mmol

Question 36

What's the target HbA1c for most diabetics?

Answer 36

48-58 mmol

Question 37

What does HbA1c measure? What is it an indicator of?

Answer 37

Measures glycated haemoglobin | Indicator of blood glucose control over 2-3 months

Question 38

What's the difference between bicarbonate levels in DKA and HHS?

Answer 38

In DKA, bicarb is low | It's high in HHS

Question 39

Which ketones should you measure in the urine? | Which ketones should you measure in the blood?

Answer 39

Urine: acetoacetate Blood: beta hydroxybutyrate

Question 40

What should be used to screen for diabetic kidney disease?

Answer 40

ACR | Albumin creatinine ratio

Question 41

Give some reasons for microalbuminuria false positives

Answer 41

Pregnancy UTI Vaginal discharge

Question 42

What's the blood pressure target for diabetics?

Answer 42

<130 / 80

Question 43

What constitutes MILD background diabetic retinopathy (R1)? What's the appropriate next step?

Answer 43

``` Dot and blot haemorrhages Microaneurysms Hard exudates Cotton wool spots (ischaemia) Flame haemorrhages ``` Reassess in 12 months

Question 44

What constitutes OBSERVABLE background diabetic retinopathy (R2)? What's the appropriate next step?

Answer 44

4 or more blot haemorrhages in one hemi field only Reassess in 6 months (or refer to ophthalmology)

Question 45

What constitutes referable background diabetic retinopathy (R3)?

Answer 45

Any of the following: - 4 or more blot haemorrhages in both inferior and superior hemi fields - venous bleeding - intra-retinal microvascular abnormalities

Question 46

What constitutes proliferative diabetic retinopathy (R4)?

Answer 46

Active new vessels or vitreous haemorrhage Refer and treat (e.g. laser therapy)

Question 47

First line test in secondary amenorrhoea?

Answer 47

``` Pregnancy test (human chorionic gonadotropin, hCG) ```

Question 48

What is primary and secondary hypogonadism in females?

Answer 48

``` Primary = problem with ovaries Secondary = problem with hypothalamus or pituitary ```

Question 49

WHO classifies ovulatary disorders as Group I, II and III. What is each of these groups and how would you investigate each one?

Answer 49

Group I: hypothalamic pituitary failure - progesterone challenge test (negative - oestrogen deficiency) Group II: hypothalamic pituitary dysfunction - progesterone challenge test (positive - normal oestrogen) - e.g. PCOS Group III: ovarian failure / hypergonadotrophic hypogonadism. - measure TSH / LH (will be raised, but low oestrogen)

Question 50

What's progesterone challenge testing?

Answer 50

Give progesterone. If period follows it indicates normal oestrogen levels (= positive, as with group II ovulation disorders). If period doesn't follow 5 days of progesterone, oestrogen levels are low (negative result, as with group I and III)

Question 51

What group of ovulatary disorder is suggested by LOW FSH and LOW LH?

Answer 51

Group I (pituitary / hypothalamic failure)

Question 52

Results of low oestradiol, and low / normal FSH and LH are suggestive of what?

Answer 52

Secondary hypothalamic amenorrhoea | i.e. hypogonadism due to pituitary or hypothalmic problems

Question 53

What 2 `things would you look for in terms of ovarian morphology on ultrasound in PCOS?

Answer 53

Increased ovarian volume (>10ml) >12 follicles between 2 and 8mm in diameter

Question 54

What are LH levels in PCOS?

Answer 54

High | raised LH : FSH ratio

Question 55

What are testosterone levels usually in PCOS?

Answer 55

High

Question 56

What would gonadotrophin levels be in primary ovarian failure?

Answer 56

High (FSH and LH)

Question 57

What would oestrogen levels be in primary ovarian failure?

Answer 57

Low

Question 58

In men with hypogonadism (and therefore low testosterone), what would LH and FSH levels be in a) primary hypogonadism b) secondary hypogonadism

Answer 58

a) primary = High FSH and LH | b) secondary = pituitary or hypothalmic problems, so low LH / FSH

Question 59

What would testosterone and FSH / LH levels be in Kleinfelters? (47 XXY)

Answer 59

Low testosterone High FSH / LH elevtaed SHBG (sex hormone binding globulin)

Question 60

What would testosterone and FSH / LH levels be in Kallman's?

Answer 60

``` Low testosterone (results in delayed or absent puberty - due to loss of GnRH secretion) ```

Question 61

What measurement can be taken to confirm ovulation?

Answer 61

Mid-cycle LH (day 21)