T1 L4 & 5 Calcium homeostasis Flashcards

1
Q

What can cause too much hormone to be produced?

A

Single nodule
Multiple nodules
Generalised increase in tissue (hyperplasia)

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2
Q

What are the layers of the adrenal glands?

A

Zona glomerulosa
Zona fasciculata
Zona reticularis
Medulla

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3
Q

What is primary hyperaldosteronism?

A

Conn’s syndrome
Excess production of hormone aldosterone from the adrenal glands which leads to low renin levels
Occurs in zona glomerulosa

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4
Q

What are the adrenal causes of hypertension?

A

Primary hyperaldosteronism

Phaeochromocytoma

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5
Q

What are the causes of too much aldosterone in the zona glomerulosa?

A

Adenoma
Hyperplasia
Rare genetic causes

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6
Q

What hypertensive patients should be screened?

A

Hypokalaemia
Resistant hypertension
Younger people

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7
Q

What tests can be used to diagnose primary hyperaldosteronism?

A

Initial screening tests: suppressed renin, normal / high aldosterone
Confirmatory tests: oral or Iv sodium suppression test

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8
Q

What tests can be done to find the cause of primary hyperaldosteronism?

A

Adrenal CT scan
Adrenal venous sampling
Metomidate PET CT

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9
Q

What treatment is given for unilateral adenoma?

A

Laparoscopic adrenalectomy

Medical treatment

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10
Q

What treatment is given for bilateral hyperplasia?

A
Medical treatment (aldosterone antagonists)
Spironolactone
Eplerinone
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11
Q

What does phaeochromocytoma cause?

A

Increased adrenaline and noradrenaline leading to raised BP

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12
Q

What catecholamines does the adrenal medulla produce?

A

Dopamine
Norepinephrine
Epinephrine

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13
Q

How does phaeochromocytoma present?

A

Spells of headache, sweating, pallor, palpitation, anxiety

Hypertension (permanent or intermittent)

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14
Q

What genetic conditions are associated with phaeochromocytoma?

A

Neurofibromatosis type 1 (NF1)
Multiple endocrine neoplasia type 2 (MEN 2)
Von Hippel-Lindau syndrome

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15
Q

What is the biochemical diagnosis for phaeochromocytoma?

A

24 hour urine: normetanephrines and metanephrines will be high. 3 methoxytyromine

Plasma: noradrenalin, adrenalin and metanephrines

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16
Q

Why can’t you measure urine dopamine when diagnosing phaeochromocytoma?

A

This comes from the kidney and the nervous system and not from the adrenal medulla

17
Q

What are some other causes of raised catecholamines?

A

Obstructive sleep apnoea
Amphetamine like drugs
L-DOPA
Labetalol

18
Q

What is the management of phaemochromocytoma?

A

Alpha blockers
Beta blockers
Laparoscopic adrenalectomy

19
Q

What are the effects of noradrenaline?

A

Vasoconstriction leading to increased BP and pallor

Glycogenolysis

20
Q

What are the effects of adrenaline?

A

Vasoconstriction
Vasodilation in muscle
Increased heart rate
Sweating

21
Q

Why does hypocalcaemia destabilise neurons?

A

1) Decrease in extracellular calcium concentration
2) Increased membrane permeability to sodium
3) Sodium depolarises membrane
4) Action potential

22
Q

What are the physical signs of hypocalcaemia?

A

Carpopedal spasm

Chvostek’s sign

23
Q

What is carpopedal spasm?

A

Occlude brachial artery using BP cuff causes a carpal spasm

24
Q

What is Chvostek’s sign?

A

Abnormal reaction to stimulation of facial nerve

Tap facial nerve at angle of jaw causes facial muscles on same side to contract

25
Q

What are the acute consequences of hypercalcaemia

A

Thirst and polyuria

Abdominal pain

26
Q

What are the chronic consequences of hypercalcaemia?

A
Constipation
Musculoskeletal aches / weakness
Neurobehavioural symptoms
Renal calculi 
Osteoporosis
27
Q

How much calcium is protein bound?

A

40%
Albumin bound - 90%
Globulin bound - 10%

28
Q

How much calcium is bound to cations?

A

10%

29
Q

How much calcium is ionised?

A

50%

30
Q

What can make the corrected calcium inaccurate?

A

Albumin concentration below 20g/l

Severe acute illness

31
Q

What are the normal levels of calcium in the blood?

A

2.15-2.55mmoles/l

32
Q

What does activation of calcium-sensing receptor cause?

A

Activation of phospholipase C leading to DAG & IP3
Inhibition of adenylate cyclase which suppresses intracellular concentration of cAMP
Can activate mitogen-activated protein kinase pathway

33
Q

What is primary hyperparathyroidism?

A

Body has too much parathyroid hormone

34
Q

What are the symptoms of primary hyperparathyroidism

A
Fatigue
Fractures
Decreased height
Upper abdominal pain
Loss of appetite
Nausea
Muscle pain
Depression
Kidney stones
35
Q

What test results diagnose primary hyperparathyroidism?

A

Raised serum calcium
Lowered serum phosphate
Raised PTH
Bone X-ray may show bone reabsorption or fractures
Imaging of kidneys or ureters may show calcification or blockage

36
Q

What is the treatment for primary hyperparathyroidism?

A

Drinking more fluids to prevent kidney stones
Avoiding immobilisation
Avoiding thiazide-like diuretics

37
Q

What are the complications of primary hyperparathyroidism?

A

Osteoporosis

Bone cysts if severe

38
Q

What are the causes of hypoparathyroidism?

A

Iatrogenic - thyroidectomy, radical neck surgery
Autoimmune
Hypomagnesaemia
Genetic mutations

39
Q

What are some common causes of secondary hyperparathyroidism?

A

Low / low normal serum calcium and hight PTH
Low serum 25 OH vitamin D (lack of sun exposure, GI problems)
Renal failure