Endocrinology Flashcards

1
Q

What are the two endogenous chemicals that increase serum Ca2+ levels in the body?

A

1,25-(OH)2-DH

  1. Increases Ca2+ and PO4 absorption from the gut
  2. Increase Ca2+ resorption from bone
  3. Increases renal tubular Ca2+ and PO4 resorption

= primary ligand for vitamin D receptor in many tissues -> binds to vitamin D receptor in intestine, inducing expression of transport proteins

PTH

  1. Increases kidney Ca2+ resorption
  2. Decreases PO4 resorption
  3. Increases activity of kidney hydroxylase -> increased 1,25-(OH)2-D production

Main regulator of PTH release = serum Ca2+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the most common MODY type?

A

MODY3

MODY2, MODY3 and MODY5 make up for 90% all MODYs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the characteristics of MODY2, MODY3, MODY 5, MODY1?

A

MODY2
Second most common
Gene = glucokinase (mild decrease in beta-cell response to glucose)
Hyperglycaemia mild and non-progressive

MODY3
Most common
Gene = HNF-1 alhpa (hepatocyte nuclear factor)
Very sensitive to sulfonylureas

MODY5
Gene = HNF1-beta
Associated with: renal cysts/dysfunction, pancreatic exocrine dysfunction, hypospadias, joint laxity, uterine abnormalities

MODY1
Gene = HNF4-alpha
Very sensitive to sulfonylureas
Decreased levels of TAGs and apolipoprotein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Other than T1DM/T2DM, what are other rarer types of DM?

A
  1. Genetic defects of beta-cell function
    - > MODY
  2. Mitochondrial gene defects
    - > Wolfram syndrome 1 (diabetes insipidus, DM, optic atrophy, deafness = DIDMOAD); Wolfram 2 (no diabetes insipidus)
    - > avoid metformin (risk of severe lactic acidosis)
  3. Neonatal diabetes mellitus
    - > transient vs. permanent, IPEX (immunodysregulation, polyendocrinopathy and enteropathy, X-linked)
  4. Genetic defects of insulin action (mutation in insulin receptor)
    - > Donohue syndrome (IUGR, fasting hypoglycaemia, postprandial hyperglycaemia, profound insulin resistance), Rabson-Mendenhall syndrome (extreme insulin resistance, acanthosis nigricans, abnormalities teeth and nails, pineal hyperplasia), lipoatrophic diabetes, Stiff-Person (progressive stiffness, painful spasms of axial muscles), SLE
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Does an ectopic posterior pituitary gland produce anterior or posterior problems?

A

Anterior

Failure of posterior pituitary to migrate and form the infundibulum causes anterior pituitary deficiencies

Normal stalk = isolated GH deficiency
Abnormal stalk = multiple pituitary hormone deficiencies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the side effects of GH therapy?

A
SCFE 
Pseudotumour cerebri 
Transient carbohydrate intolerance 
Transient hypothyroidism 
Scoliosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Which is more specific for GH-deficiency: IGF-1 or IGF-BP3?

A

IGF-BP3
Vary less with age and nutrition -> more specific (though less sensitive) for GH action

IGF-1
Can vary greatly with age and nutritional status regardless of GH secreion -> sensitive, but not specific

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the most common anterior pituitary tumour?

A

Prolactin-secreting tumours

MRI of sella = best diagnostic tool

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the hormone that causes testicular enlargement?

A

FSH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the causes or high vs. low thyroxine-binding globulin? What is its significance?

A

Increased TPG -> increased total T4

Decreased TPG -> decreased total T4

This is because total T4 measures a combination of free T4 and bound T4

INCREASED TPG 
Oestrogen (OCP, pregnancy) 
Tamoxifen 
Narcotics 
Hepatitis, biliary cirrhosis 
DECREASED TPG 
Androgens 
Glucocorticoids 
Nephrotic syndrome 
Inherited TPG deficiency
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Does amiodarone cause hyper or hypothyroidism?

A

BOTH

Amiodarone is iodine-rich
-> also blocks peripheral deiodination of reverse T3 and T4 -> increased reverse T3 and T4, and decreased T3

HYPERthyroid = due to iodine

HYPOthyroid = too much iodine and peripheral deiodination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What type of hypothyroidism is not detected on the neonatal screening test?

A

SECONDARY hypothyroidism

Screening test does not detect low TSH levels (as seen in secondary hypothyroidism)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

When administering thyroxine to neonates/infants with hypothyroidism, what do you NOT mix it with?

A

Do NOT mix thyroxine with: (as can be bound)

Soy protein formula
Iron
Calcium supplements

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What change does alkalosis cause to calcium levels?

A

HYPOcalcaemia

As pH increases, albumin becomes more ionised into anions -> causes free calcium to bind more strongly with albumin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the counter-regulatory hormones?

A

= Hormones that counter the effect of insulin

Glucagon
Adrenaline
Cortisol
Growth hormone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why is acanthosis nigricans seen in T2DM?

A

Marker of insulin resistance

Pathogenesis = hyperinsulinaemia thought o play key role -> ?stimulate keratinocyte and dermal fibroblast proliferation via IGFR-1

Thus, seen ALSO in hyperinsulinaemic states (e.g. insulin-producing tumour)