Biochemistry (Weeks 4 + 5) Flashcards Preview

Year 2 - Endocrinology (DP) > Biochemistry (Weeks 4 + 5) > Flashcards

Flashcards in Biochemistry (Weeks 4 + 5) Deck (27):
1

What does mineralocorticoid activity refer to?

Na+ retention
In exchange for K+ and/or H+

2

What steroids have mineralocorticoid activity?

Aldosterone (main one)
Others:
- Cortisol

3

What does excess mineralocorticoid activity result in?

Na+ retention

4

What does too little mineralocorticoid activity result in?

Na+ loss -> Water loss

5

What does ADH cause?

Water reabsorption -> Antidiuresis

6

What can cause hyponatraemia?

Excess water:
- Decreased secretion -> SIADH
- Increased intake -> Compulsive water drinking
Too little Na+:
- Increased Na+ loss
> Addison's
> Gut/Skin loss
- Decreased Na+ intake (rare)

7

What can cause hypernatraemia?

Too little water:
- Increased water loss -> Diabetes Insipidus
- Decreased water intake - Young/Eldery
Too much Na+:
- Rare
> Medications given as IV Na+
> Ocean near-drowning
> Infants given high-salt feeds

8

Put the following steps in order for the development of Addison's disease:
- Decreased steroid secretion
- Na+ and water loss from ECF
- Clinical dehydration
- Adrenal insufficiency
- Decreased Na+ retention
- Decreased mineralocorticoid activity
- Decreased ECF volume

1. Adrenal insufficiency
2. Decreased steroid secretion
3. Decreased mineralocorticoid activity
4. Decreased Na+ retention
5. Na+ and water loss from ECF
6. Decreased ECF volume
7. Clinical dehydration

9

Which of the following is not a feature of Addison's:
- Dizziness
- Pigmentation
- Malaise
- Fatigue
- Weight gain

Weight gain:
- Actually causes weight loss

10

What causes hyperpigmentation in Addison's disease?

Excess ACTH:
- ACTH contains melanocyte-stimulating hormone
- ACTH degraded by proteases
- MSH exposed
- Excess pigment

11

How will hyperkalaemia present as on an ECG?

Small P-waves
Peaked T-waves
Widened QRS

12

What are U-Waves (ECG) seen in?

Hypokalaemia

13

What are some non-osmotic stimuli for ADH release?

Hypovolaemia/Hypotension
Pain
Nausea/Vomiting

14

What does the 'inappropriate' mean in SIADH?

Inappropriate for the osmolal state

15

Why can the clinical volume status be unremarkable in SIADH?

The retained water is often distributed across all body compartments

16

What is the pathogenesis of central diabetes insipidus?

1. Pituitary/Pituitary stalk disruption
2. No ADH secretion
3. Decreased water reabsorption
4. Loss of pure water in urine

17

What effect does DI have on Na+ levels?

Increased levels

18

How is diabetes insipidus treated?

Exogenous ADH -> Desmopressin

19

What are signs and symptoms of diabetes insipidus?

Head injury (RTA)
High urine output
Fluid replacement high -> Slow fall in [NA+]

20

What is the volume status of hypovolaemia?

Water deficit
Hypovolaemia + Hyponatraemia = Decreased Na+

21

Is hypo- or hypernatraemia serious?

If very low ( YES
If very high (>155mmol/L) -> YES

22

What symptoms can be seen in hypo- or hypernatraemia?

Altered AVPU
Confusion
Nausea

23

What is pseudohyponatraemia?

When there are excess proteins and lipoproteins in a serum sample:
- [Na+] in serum water is the same
- [Na+] in total serum appears reduced

24

How can a patient's volume status indicate the cause of hyponatraemia?

If dry -> Too little Na+
If not dry -> Too much water

25

If a patient is dry (ie too little Na+) what can be causing it?

Decreased intake (rare)
Increased loss:
- Gut, skin or kidney?
> Gut and skin loss is obvious

26

If there is suspected Addison's what should be done?

Measure:
- Cortisol
- ACTH
If patient unwell:
- Give Na+ replacement

27

How should the following scenarios be treated:
1. Too little Na+
2. Too much water
3. Too little water
4. Too much Na+

1. Give Na+
2. Restrict fluids
3. Give fluids (water)
4. Diuretics -> Natriuresis:
- Replace water loss