Reference values - Own notes!

Question 1

According to American Diabetic Association (ADA) diagnostic criteria for DM,
what is the cut-off value of
1. Fasting plasma glucose
2. 2-hourpost-oral glucose tolerance test plasma glucose
3. HbA1c
4. Random plasma glucose

? (please provide unit)

Answer 1

1. <7.0 mmol/L
2. <11.1 mmol/L
3. <6.5 %
4. > 11.1 mmol/L

Question 2

What is the fasting plasma glucose range that accounts for impaired fasting glucose level?

Answer 2

5. 6-7 mmol/L

normal: <5.6

Question 3

What is the plasma glucose range that accounts for impaired glucose tolerance after OGTT?

Answer 3

7.8 - 11.1 mmol/L

notmal <7.8

Question 4

How do we differentiate Gestational DM and DM in pregnancy?

Answer 4

OFTT performed at 6-12 weeks postpartum:

1. at 0 min, normal <5.1
   - Gestational DM: 5.1-6.9; DM in pregnancy: >7
2. at 60 minutes (1 hour), normal <10.0
   - Gestational DM: >10; DM in pregnancy: –
3. at 120 minutes: normal <8.5
   - Gestational DM: 8.5-11; DM in pregnancy: >11.1

DM in pregnancy should be diagnosed one or more of OGTT criteria are met

Question 5

What are the therapeutic goals of ADA in diabetes patients?

1. Glycemic control (3)
2. BP
3. Lipid profile (3)

Answer 5

1. Glycemic control
   - HbA1c <7%
   - Pre-prandial BG 5.0-7.2
   - Post-prandial BG <10.0
2. BP <130/80
3. Lipid profile
   - TG: <1.7
   - LDL-C <1.8 (<2.6 in normal)
   - HDL-C >1.1 in M, > 1.3 in female

Question 6

How is serum osmolality calculated?

Answer 6

Calculated osmolality = 2 x [Na+]+ glucose + urea

Question 7

What is the definition of hypoglycaemia?

Answer 7

Plasma glycose <2.5 mmol/L by laboratory method

Question 8

In normal circumstances in normal patient, how should the body respond to a short synacthen test? (correct unit please!)

Answer 8

Cortisol level should rise to >450 nmol/L

Question 9

In patients with

i) primary adrenal insufficiency
ii) secondary adrenal insufficiency,

how would they react to the short synacthen test?

Answer 9

i) no increase in cortisol, with increased baseline ACTH level
ii) sluggish response in cortisol level, with undetectable ACTH level

Question 10

What is a glucagon stimulation test?

How would a normal individual respond to a glucagon stimulation test? (2)

Answer 10

• Induce hyperglycaemia thus reactive hypoglycaemia and stress > test both adrenocortical and GH-IGF axis
  1. Cortisol during hypoglycaemic attack should increase to >450 nmol/L
  2. GH during hypoglycaemic attack should increase to >20 ng/mL

Question 11

What is the definition of neonate hypoglycaemia?

1. Full-term baby
2. Pre-term infant

Answer 11

1. Full-term baby: plasma glucose <2.0mmol/L

2. Pre-term infant: plasma glucose <1.1 mmol/L

Question 12

What are the differential diagnosis for hypercortisolism?

Answer 12

1. Cushing’s disease - pituitary adenoma secreting ACTH
2. Adrenal adenoma (primary)
3. Ectopic source of ACTH - e.g. SCLC
4. Iatrogenic: treatment with exogenous glucocorticoids

Question 13

What are the investigations for hypercortisolism?

Describe.

Answer 13

1. Overnight dexamethasone depression test
   - dexamethasone 1mg at 23:00, then measure cortisol in the next morning
2. High dose dexamethasone depression test
   - 2mg Q6h x 2 days

Question 14

If the hypercortisolism is due to

1. Adrenal cause (primary)
2. Pituitary adenoma secreting ACTH
3. Ectopic ACTH secretion

, what would you expect in the 2 investigations respectively?

Answer 14

1. Primary adrenal cause
   ONDST - unchanged
   HDDST - unchanged
2. Pituitary adenoma secreting ACTH
   ONDST - unchanged
   HDDST - decreased >50%
3. Ectopic ACTH secretion
   ONDST - unchanged
   HDDST - unchanged

Question 15

What test is used to confirm primary hyperaldosteronism? What are the expected results in normal individuals and abnormal?

Answer 15

Salt loading test
- 5 days of NaCl tablet, measure 24 hour urine aldosterone and Na

1. 24h urine Na >200 mmol/24h = adequate salt loading
2. 24h urine aldosterone >38 mol/24h = lack of aldosterone suppression with intravascular expansion

Question 16

What is the Free androgen index?

Hyperandrogenemia what level?

Answer 16

T/SHBG x100 (both in nmol/L)

> 5 = hyperandrogenemia
- e.g. CAH, PCOS, androgen-secreting tumors

Question 17

Respiratory distress syndrome is the absence of surfactant in premature infants <32 weeks.
What can be measured in amniotic fluid?

Answer 17

Lecithin-sphingomyelin ratio (L:S) in amniotic fluid <1.5 –> high risk of RDS.

• Surfactant is mostly lecithin (phospholipid)
• sphingomyelin level is constant in amniotic fluid

Question 18

What does it mean by a positive result for testing pheochromocytoma? (3)

Answer 18

24 hour urine collection

1. NA + A: 2x elevation
2. NM + M: 2x elevation
3. VMA: 3x elevation

Question 19

Name 2 endocrine tests that can be tested if you clinically suspect a pheochromocytoma.
State their respective positive results.

Answer 19

1. Glucagon stimulation test
   - stimulate catecholamine secretion from pheochromocytoma
   - Positive: NA peal 2000pg/ml or >3x increase over the baseline
2. Overnight clonidine suppression test
   - clonidine can suppress physiological catecholamine secretion, while autonomous secretion by tumor cannot.

• Clonidine 0.3mg PO at 9pm
• BP at 9pm, 11pm and 7am
• Collect urine for NA, adrenaline, creatinine
• Positive: NA/Cr >60nnol/mmol OR adrenaline/Cr >20nmol/mmol

Question 20

What are the respective risks for glucagon stimulation test and overnight clonidine suppression test.
How are the risks prevented respectively?

Answer 20

1. Glucagon stimulation test:
   - hypertensive crisis, since catecholamines are stimulated
   - standby phentolamine IV 10mg during the test
2. Overnight clonidine suppression test:
   - hypotensive shock
   - subject should remain supine throughout at night

Question 21

What is the normal lymphocyte count in CSF?

Answer 21

<5/mm3

no neutrophils!

Question 22

What is the normal
1. protein
2. glucose
levels in CSF?

Answer 22

1. Protein: 0.15-0.45g/L
   should be <0.7g/L
2. Glucose: 2.8-4.2 mmol/L
   should be >60% of plasma glucose

Question 23

What is the light’s criteria?

Answer 23

For determining whether pleural fluid is exudate or transudate. It is an exudate if (one is met)

1. Pleural/ Serum total protein > 0.5
2. Pleural/ Serum LDH >0.6
3. Pleural/ Serum LDH > 2/3 ULN of serum LDH

Question 24

How do we determine the content of ascitic fluid?

Answer 24

1. Total protein
   Transudate <30g/L
   Exudate >30g/L
2. SAAG (Serum ascites albumin gradient)
   Transudate >11g/L
   Exudate 11g/L