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

Biochemistry (Weeks 4 + 5) Flashcards

1
Q

What does mineralocorticoid activity refer to?

A

Na+ retention

In exchange for K+ and/or H+

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2
Q

What steroids have mineralocorticoid activity?

A

Aldosterone (main one)
Others:
- Cortisol

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3
Q

What does excess mineralocorticoid activity result in?

A

Na+ retention

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4
Q

What does too little mineralocorticoid activity result in?

A

Na+ loss -> Water loss

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5
Q

What does ADH cause?

A

Water reabsorption -> Antidiuresis

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6
Q

What can cause hyponatraemia?

A 
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)
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7
Q

What can cause hypernatraemia?

A

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

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8
Q

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
A
  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
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9
Q

Which of the following is not a feature of Addison’s:

  • Dizziness
  • Pigmentation
  • Malaise
  • Fatigue
  • Weight gain
A

Weight gain:

- Actually causes weight loss

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10
Q

What causes hyperpigmentation in Addison’s disease?

A

Excess ACTH:

 - ACTH contains melanocyte-stimulating hormone
 - ACTH degraded by proteases
 - MSH exposed
 - Excess pigment
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11
Q

How will hyperkalaemia present as on an ECG?

A

Small P-waves
Peaked T-waves
Widened QRS

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12
Q

What are U-Waves (ECG) seen in?

A

Hypokalaemia

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13
Q

What are some non-osmotic stimuli for ADH release?

A

Hypovolaemia/Hypotension
Pain
Nausea/Vomiting

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14
Q

What does the ‘inappropriate’ mean in SIADH?

A

Inappropriate for the osmolal state

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15
Q

Why can the clinical volume status be unremarkable in SIADH?

A

The retained water is often distributed across all body compartments

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16
Q

What is the pathogenesis of central diabetes insipidus?

A
  1. Pituitary/Pituitary stalk disruption
  2. No ADH secretion
  3. Decreased water reabsorption
  4. Loss of pure water in urine
17
Q

What effect does DI have on Na+ levels?

A

Increased levels

18
Q

How is diabetes insipidus treated?

A

Exogenous ADH -> Desmopressin

19
Q

What are signs and symptoms of diabetes insipidus?

A

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

20
Q

What is the volume status of hypovolaemia?

A

Water deficit

Hypovolaemia + Hyponatraemia = Decreased Na+

21
Q

Is hypo- or hypernatraemia serious?

A

If very low ( YES

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

22
Q

What symptoms can be seen in hypo- or hypernatraemia?

A

Altered AVPU
Confusion
Nausea

23
Q

What is pseudohyponatraemia?

A

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
Q

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

A

If dry -> Too little Na+

If not dry -> Too much water

25
Q

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

A

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

26
Q

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

A 
Measure:
     - Cortisol
     - ACTH
If patient unwell:
     - Give Na+ replacement
27
Q

How should the following scenarios be treated:

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

Year 2 - Endocrinology (DP) (15 decks)

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